Allergies

Contact dermatitis

2011-03-06T22:03:00.000-08:00

Dermatitis - contact; Allergic dermatitis; Dermatitis - allergic

Last reviewed: November 1, 2009.

Contact dermatitis is an inflammation of the skin caused by direct contact with an irritating substance.
See also: Poison ivy - oak - sumac

Causes, incidence, and risk factors

Contact dermatitis is an inflammation of the skin caused by direct contact with an irritating or allergy-causing substance (irritant or allergen). Reactions may vary in the same person over time. A history of any type of allergies increases the risk for this condition.

Irritant dermatitis, the most common type of contact dermatitis, involves inflammation resulting from contact with acids, alkaline materials such as soaps and detergents, solvents, or other chemicals. The reaction usually resembles a burn.

Allergic contact dermatitis, the second most common type of contact dermatitis, is caused by exposure to a substance or material to which you have become extra sensitive or allergic. The allergic reaction is often delayed, with the rash appearing 24 - 48 hours after exposure. The skin inflammation varies from mild irritation and redness to open sores, depending on the type of irritant, the body part affected, and your sensitivity.

Overtreatment dermatitis is a form of contact dermatitis that occurs when treatment for another skin disorder causes irritation.

Common allergens associated with contact dermatitis include:

Poison ivy, poison oak, poison sumac
Other plants
Nickel or other metals
Medications
- Antibiotics, especially those applied to the surface of the skin (topical)
- Topical anesthetics
- Other medications
Rubber or latex
Cosmetics
Fabrics and clothing
Detergents
Solvents
Adhesives
Fragrances, perfumes
Other chemicals and substances

Contact dermatitis may involve a reaction to a substance that you are exposed to, or use repeatedly. Although there may be no initial reaction, regular use (for example, nail polish remover, preservatives in contact lens solutions, or repeated contact with metals in earring posts and the metal backs of watches) can eventually cause cause sensitivity and reaction to the product.

Some products cause a reaction only when they contact the skin and are exposed to sunlight (photosensitivity). These include shaving lotions, sunscreens, sulfa ointments, some perfumes, coal tar products, and oil from the skin of a lime. A few airborne allergens, such as ragweed or insecticide spray, can cause contact dermatitis.

Symptoms

Itching (pruritus) of the skin in exposed areas
Skin redness or inflammation in the exposed area
Tenderness of the skin in the exposed area
Localized swelling of the skin
Warmth of the exposed area (may occur)
Skin lesion or rash at the site of exposure
- Lesions of any type: redness, rash, papules (pimple-like), vesicles, and bullae (blisters)
- May involve oozing, draining, or crusting
- May become scaly, raw, or thickened

Signs and tests

The diagnosis is primarily based on the skin appearance and a history of exposure to an irritant or an allergen.

According to the American Academy of Allergy, Asthma, and Immunology, "patch testing is the gold standard for contact allergen identification." Allergy testing with skin patches may isolate the suspected allergen that is causing the reaction.

Patch testing is used for patients who have chronic, recurring contact dermatitis. It requires three office visits and must be done by a clinician with detailed experience in the procedures and interpretation of results. On the first visit, small patches of potential allergens are applied to the skin. These patches are removed 48 hours later to see if a reaction has occurred. A third visit approximately 2 days later is to evaluate for any delayed reaction. You should bring suspected materials with you, especially if you have already tested those materials on a small area of your skin and noticed a reaction.

Other tests may be used to rule out other possible causes, including skin lesion biopsy or culture of the skin lesion (see skin or mucosal biopsy culture).

Treatment

Initial treatment includes thorough washing with lots of water to remove any trace of the irritant that may remain on the skin. You should avoid further exposure to known irritants or allergens.
In some cases, the best treatment is to do nothing to the area.

Corticosteroid skin creams or ointments may reduce inflammation. Carefully follow the instructions when using these creams, because overuse, even of low-strength over-the-counter products, may cause a troublesome skin condition. In severe cases, systemic corticosteroids may be needed to reduce inflammation. These are usually tapered gradually over about 12 days to prevent recurrence of the rash. In addition to or instead of corticosteroid skin treatment, your doctor may prescribe tacrolimus ointment or pimecrolimus cream.

Wet dressings and soothing anti-itch (antipruritic) or drying lotions may be recommended to reduce other symptoms.

Expectations (prognosis)

Contact dermatitis usually clears up without complications within 2 or 3 weeks, but may return if the substance or material that caused it cannot be identified or avoided. A change of occupation or occupational habits may be necessary if the disorder is caused by occupational exposure.

Complications

Secondary bacterial skin infections may occur.

Calling your health care provider

Call your health care provider if symptoms indicate contact dermatitis and it is severe or there is no improvement after treatment.

Prevention

Avoid contact with known allergens. Use protective gloves or other barriers if contact with substances is likely or unavoidable. Wash skin surfaces thoroughly after contact with substances. Avoid overtreating skin disorders.

References

Gober MD, DeCapite TJ, Gaspari AA. Contact dermatitis. In: Adkinson NF Jr, ed. Middleton’s Allergy: Principles and Practice. 7th ed. Philadelphia, Pa: Mosby Elsevier; 2008:chap 63.
Habif TP. Contact dermatitis and patch testing. In: Habif TP, ed. Clinical Dermatology. 5th ed. Philadelphia, Pa: Mosby Elsevier; 2009:chap 4.

: Review Date: 11/1/2009.
Reviewed by: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Figures

Poison oak rash on the arm

Poison oak rash on the arm. Several plants produce toxins that cause skin reaction. This is the appearance of poison oak dermatitis. Note the typical linear streaks produced either by scratching or brushing against the plant. (Image courtesy of the Centers for Disease Control and Prevention.)

Review Date: 10/13/2009.
Reviewed by: Jacob L. Heller, MD, MHA, Emergency Medicine, Virginia Mason Medical Center, Seattle, Washington. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Latex allergy

Allergy to latex products may manifest itself in simple dermatitis, or in a more serious whole body reaction, anaphylaxis. The term "dermatitis" describes an inflammatory response of the skin, caused by contact with allergens or irritants such as the latex in surgical gloves or condoms. Contact with latex may produce an itchy rash, redness, blisters and scaling, or may cause the more severe anaphylaxis. Anaphylaxis is a series of symptoms including dropping blood pressure, swelling of the throat and tongue and difficulty breathing.

Review Date: 11/1/2009.
Reviewed by: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Poison plants

The term "dermatitis" describes an inflammatory response of the skin, caused by contact with allergens or irritants, exposure to sunlight, or by poor circulation, even stress. An example of contact dermatitis is the reaction of a sensitive person's skin to poison ivy, oak or sumac. Contact with these plants, which contain a chemical called urushiol, produces an itchy rash, redness, blisters and scaling. AVOID SCRATCHING. Scratching the rash may spread the inflammation, lead to infection and even leave scars.

Review Date: 11/1/2009.
Reviewed by: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Dermatitis, nickel on the sole

The metal, nickel, can cause inflammation (erythema), rash, and itching. Nickel dermatitis is relatively common, and can be seen on the wrist from the stainless backs of watches, on the earlobes from nickel plated earrings, or elsewhere on the body from snaps. This person was in contact with something made of nickel or containing nickel salts.

Review Date: 11/1/2009.
Reviewed by: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Dermatitis, contact

This picture shows a skin inflammation (dermatitis) caused by contact with a material that causes an allergic reaction in this person. Contact dermatitis is a relatively common condition, and can be caused by many substances.

Review Date: 6/29/2010.
Reviewed by: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; Paula J. Busse, MD, Assistant Professor of Medicine, Division of Clinical Immunology, Mount Sinai School of Medicine, New York, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Dermatitis, close-up of allergic contact

This is an example of an allergic skin reaction (allergic dermatitis) caused by hair dye. The skin on the neck is red (erythematous), thickened (lichenified), scaly, and crusted.

Review Date: 11/1/2009.
Reviewed by: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Dermatitis, contact on the cheek

This picture shows a person with a skin inflammation (dermatitis) on the cheek caused by contact with a substance that produced an allergic reaction (allergen). Contact dermatitis causes redness, itching, and small blisters (vesicles).

Review Date: 11/1/2009.
Reviewed by: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Dermatitis, pustular contact

This is a close-up of a dermatitis reaction. It consists of a large, red (erythematous) lesion (plaque) with numerous small pus-filled areas (pustules).

Review Date: 10/28/2010.
Reviewed by: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Poison ivy on the knee

This is a typical early appearance of a poison ivy rash, located on the knee. These early lesions consist of multiple small blisters (vesicles), often in a line where the skin has brushed against the poison ivy plant.

Review Date: 10/28/2010.
Reviewed by: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Poison ivy on the leg

This is a typical early appearance of a poison ivy rash, located on the leg. These early lesions consist of multiple small blisters, often in a line where the skin has brushed against the poison ivy plant. The rash is caused by skin contact with the oily sap (resin) of these plants. The oily resin usually enters the skin rapidly, and is seldom transferred from person to person. The rash is not caused by the fluid from the blisters. Thus, once the person has washed the oil off the skin, the rash is usually not contagious.

Review Date: 10/28/2010.
Reviewed by: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Phytophotodermatitis on the hand

This person is sensitive to chemicals used in perfumes, and now develops a rash when the area is exposed to light (Phytophotodermatitis). These perfumes include Oil of Bergamot, an oil also found in some citrus fruits and wild plants. It results in streaky redness (erythema) and pigmentary changes.

Review Date: 11/1/2009.
Reviewed by: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Atopic eczema

2011-02-13T22:13:00.000-08:00

Eczema is a chronic skin disorder that involves scaly and itchy rashes. as well as blistering, weeping, or peeling of the skin. Atopic eczema is the most common type.

Causes, incidence, and risk factors

Atopic eczema is due to a hypersensitivity reaction (similar to an allergy) in the skin, which leads to long-term inflammation.

Eczema is most common in infants. Many people outgrow it by early adulthood. The condition tends to run in families.

People with eczema often have a family history of allergic conditions such as asthma, hay fever, or eczema.

The following can make eczema symptoms worse:

Allergies to pollen, mold, dust mites, or animals
Colds or the flu
Contact with rough materials
Dry skin
Exposure to environmental irritants
Exposure to water
Feeling too hot or too cold
Fragrances or dyes added to skin lotions or soaps
Stress

Symptoms

Typical skin changes may include:

Blisters with oozing and crusting
Ear discharge or bleeding
Raw areas of the skin from scratching
Skin coloring changes -- more or less coloring than the normal skin tone (See: Skin abnormally dark or light)
Skin redness or inflammation around the blisters
Thickened or leather-like areas, called lichenification, which can occur after long-term irritation and scratching

Both the type of rash and where the rash appears can depend on the age of the patient:

In children younger than age 2, skin lesions begin on the face, scalp, hands, and feet. It is often a crusting, bubbling, or oozing rash.
In older children and adults, the rash is more commonly seen on the inside of the knees and elbows, as well as the neck, hands, and feet.
During a severe outbreak, rashes may occur anywhere on the body.

Itching, which is sometimes intense, almost always occurs. Itching may start even before the rash appears.

Signs and tests

Diagnosis is primarily based on:

Appearance of the skin
Personal and family history

The health care provider should examine the lesions to rule out other possible causes. A skin lesion biopsy may be performed, but is not always needed to make the diagnosis.

Allergy skin testing may be helpful for people with:

Difficult-to-treat eczema
Other allergy symptoms

Treatment

CARE AT HOME

Taking care of your skin at home may reduce the need for medications.

Avoid scratching the rash or skin if you can:

Relieve the itch by using a cold compress and taking antihistamines to reduce severe itching.
Keep your child's fingernails cut short. Consider light gloves if nighttime scratching is a problem.

Keep the skin moist (called lubricating or moisturizing the skin). Use ointments (such as petroleum jelly), creams, or lotions 2 - 3 times a day. Moisturizers should be free of alcohol, scents, dyes, fragrances, or other chemicals.

Avoid anything that makes your symptoms worse. This may include:

Foods such as dairy, peanuts, eggs, or wheat (always discuss with your doctor first)
Irritants such as wool and lanolin
Strong soaps or detergents, as well as chemicals and solvents
Sudden changes in body temperature and stress, which may cuase sweating and worsen the condition
Triggers that cause allergy symptoms

When washing or bathing:

Keep water contact as brief as possible and use less soap than usual. Short, cooler baths are better then long, hot baths.
Do not scrub or dry the skin too hard or for too long.
After bathing, it is important to apply lubricating creams, lotions, or ointment on the skin while it is damp. This will help trap moisture in the skin.

MEDICATIONS

Antihistamines taken by mouth may help with itching or if you have allergies. Often you can buy them without a prescription.

Some antihistamines can cause sleepiness, but may help with scratching while sleeping.
Newer antihistamines cause little or no sleepiness. Some are available over the counter. These medications include fexofenadine (Allegra), loratadine (Claritin, Alavert), and cetirizine (Zyrtec).

Most causes of atopic eczema are treated with medications that are placed directly on the skin or scalp (called topical medicines):

At first, you will probably be prescribed a mild cortisone (or steroid) cream or ointment. If this doesn't work, you may need a stronger steroid medicine. You may need different strengths of steroids for different areas of skin.
Medicines called topical immunomodulators (TIMs) may be prescribed for anyone over 2 years old. TIMs include tacrolimus (protopic) and pimecrolimus (Elidel). Ask your doctor about concerns over a possible cancer risk associated with the use of these medicines.
Creams or ointments that contain coal tar or anthralin may be used for thickened areas.

Other medicines that may be used include:

Oral or injected corticosteroids when the eczema is severe
Antibiotic creams or pills if the skin is infected
Allergy shots (immunotherapy)

Expectations (prognosis)

Eczema is a chronic condition, but you can control it with treatment, by avoiding irritants, and by keeping the skin well-moisturized.

In children, it often clears beginning around age 5 - 6, but flareups will often occur. In adults, it is generally a long-term or recurring condition.

People with eczema tend to have dry skin that flares up more in the winter, when the air is cold and dry.

Complications

Infections of the skin caused by bacteria, fungi, or viruses
Permanent scars

Calling your health care provider

Call for an appointment with your health care provider if:

Eczema does not respond to moisturizers or avoiding allergens
Symptoms worsen or treatment is ineffective
You have signs of infection (such as fever, redness, pain)

Prevention

Studies have shown that children who are breast-fed are less likely to get eczema. This is also true when the nursing mother has avoided cow's milk in her diet. Other dietary restrictions may include eggs, fish, peanuts, and soy.

Eczema tends to run in families. Controlling stress, nervousness, anxiety, and depression can help in some cases. Keeping the skin well-moisturized and avoiding irritants is important.

References

Excema and Hand Dermatitis. In: Habif TP, ed. Clinical Dermatology. 4th ed. St. Louis, Mo: Mosby; 2004:chap 3.

Lewis-Jones S, Mugglestone MA; Guideline Development Group. Management of atopic eczema in children aged up to 12 years: summary of NICE guidance. BMJ. 2007;335:1263-1264. [PubMed]

Ascroft DM, Chen LC, Garside R, Stein K, Williams HC. Topical pimecrolimus for eczema. Cochrane Database Syst Rev. 2007 Oct 17;(4):CD005500. [PubMed]

Review Date: 10/26/2009.

Reviewed by: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Keratosis pilaris - close-up

Keratosis pilaris is seen most commonly during childhood and presents as small, rough, raised lesions (papules). These papules are described as "spiny and keratotic" and are typically skin colored. The papules are usually found on the outer surface of the upper arms and thighs, although it may occur elsewhere on the body. The roughness is accentuated by dry skin and the condition is often worse in the winter. It tends to be inherited and may be associated with atopic dermatitis.

Review Date: 10/26/2009.

Atopic dermatitis

The term "dermatitis" describes an inflammatory response of the skin, caused by contact with allergens or irritants, exposure to sunlight, or by poor circulation, even stress. An example of atopic dermatitis is eczema, an itchy rash that produces redness, blisters and scaling. AVOID SCRATCHING. Scratching the rash may spread the inflammation, lead to infection and even leave scars.

Review Date: 10/26/2009.

Atopy on the ankles

Atopic dermatitis occurs in individuals with tendencies towards allergies and who seem to have very sensitive skin. The persistent itching often encourages scratching, causing the skin to become raw or leathery. Here, the ankles and feet are affected.

Review Date: 10/26/2009.

Dermatitis, atopic on the arms

This person has inherited allergic skin inflammation (atopic dermatitis) on the arms. Red (erythematous), scaly plaques can be seen on the inside of the elbows (antecubital fossa). In adults, atopic dermatitis usually involves the body creases, or flexural areas (antecubital fossa and popliteal fossa).

Review Date: 10/26/2009.

Dermatitis, atopic in an infant

Atopic dermatitis is quite often seen on the cheeks of infants. It consists of red (erythematous), scaling plaques that are diffusely scattered over the infant's body and face.

Review Date: 10/26/2009.

Hyperlinearity in atopic dermatitis, on the palm

This picture shows a manifestation of atopic dermatitis on the palm. Individuals with atopic dermatitis characteristically have increased numbers and depth of skin lines (hyperlinearity) on the palms with little redness (erythema).

Review Date: 10/26/2009.

Eczema, atopic - close-up

This view shows the red (erythematous) scaly patches (plaques) characteristic of atopic dermatitis.

Review Date: 10/26/2009.

Dermatitis, atopic on a young girl's face

Lupus erythematosis often produces a "butterfly rash" or malar rash, seen here on a young girl's face. This is the characteristic appearance of the butterfly rash.

Review Date: 10/26/2009.

Keratosis pilaris on the cheek

Keratosis pilaris occurs most commonly during childhood and produces small, rough spots (papules) that are typically skin-colored. They usually appear over the outer surface of the upper arms and thighs, but may also occur elsewhere on the body. Dry skin (especially during winter months) makes the condition worse. Keratosis pilaris tends to be inherited and may be associated with atopic dermatitis.

Review Date: 12/11/2009.

Reviewed by: Michael Lehrer, MD, Department of Dermatology, University of Pennsylvania Medical Center, Philadelphia, PA. Review provided by VeriMed Healthcare Network; Linda Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Dermatitis, atopic on the legs

These red (erythematous), scaly plaques on the legs are caused by an inherited allergic condition called atopic dermatitis. Many of these areas have been scratched until they are raw and infected, with the infection triggering and perpetuating the problem. In adults, atopic dermatitis frequently involves the body creases (inside elbows, behind knees).

Review Date: 10/26/2009.

Hyperlinearity in atopic dermatitis

People with atopic dermatitis frequently have thickening of the skin on the palms and soles with an increase in the number of lines in the skin (hyperlinearity). This characteristic is closely associated with genetic predisposition (atopy ).

Review Date: 10/26/2009.

Allergy to mold - animal dander - dust

2011-02-13T22:08:00.000-08:00

Allergy-related symptoms can occur after you are around mold, certain animals or animal hair, dust, and other substances. These substances are usually found indoors and do not cause symptoms for most people.

Causes, incidence, and risk factors

Allergies occurs when the immune system over-reacts to substances (allergens) that are usually harmless.

When a person with allergies breathes in an allergen, the body releases histamine and other chemicals as part of the immune response. This causes itching and swelling, mucus production, and in serious cases, hives and rashes, as well as other symptoms. Symptoms vary in severity from person to person.

Most environmental allergens contact the skin or eyes, or are inhaled. Therefore, most symptoms affect the skin, eyes, or the breathing passages.

You may develop an allergic reaction to particles that may be in or outdoors. Common allergy triggers include:

Mold -- Mold spores are carried in the air and may be present all year long. Mold is most common indoors in damp locations such as basements, bathrooms, or washrooms. Fabrics, rugs, stuffed animals, books, or wallpaper can contain mold spores if they are kept in a damp place. Outdoors, mold lives in the soil, on compost, and on damp vegetation.
Animals -- People who are allergic to certain animals are rarely allergic to the animals' fur or feathers. They are actually allergic to the small scales of skin (dander) that the animal sheds. Some people are allergic to the animal's saliva, particularly cats. Cats have saliva that contains a protein known to cause allergy. You can come into contact with animal saliva if the pet licks you, if you touched the pet after it has groomed itself, or if you touch an object that the animal has recently licked or chewed. Similar reactions can occur with dog saliva exposure.
Dust -- House dust contains tiny particles of pollen, mold, fibers from clothing and fabrics, detergents, and microscopic insects (mites). Dust mites, including small fragments of dead mites, are the primary cause of dust allergy and are found in the highest numbers in bedding, mattresses, and box springs.

A few people develop allergy-like symptoms to other irritants in the environment, including smoke, fumes from industries or cleaning products, tobacco, powder, and laundry detergents.

Symptoms

Coughing
Difficulty breathing
Hives
Itching of the nose, eyes, throat, or skin
Rash
Redness in the eyes
Runny nose
Sinus pressure
Sneezing
Tearing eyes
Wheezing

Signs and tests

The doctor will perform a physical exam and ask you questions about your symptoms. The history of symptoms is important in diagnosing allergies, including whether the symptoms vary according to time of day or the season and possible exposures such as having a pet in the household.

Allergy testing is done to see identify the specific allergens that are causing your symptoms. Skin testing is the most common and useful method.

If your doctor determines that you cannot undergo skin testing, a RAST blood test (to look for IgE antibodies to a specific allergen) may be helpful.

Having allergies may also alter the results of your white blood cell (WBC) count, particularly an eosinophil count.

Treatment

The best treatment is to avoid being around molds, dander, dust.

See the following articles for specific treatment options:

Asthma
Allergic rhinitis
Atopic eczema
Allergic conjunctivitis

Allergy shots (immunotherapy) are occasionally recommended if the substance you are allergic to cannot be avoided and if symptoms are hard to control.

Expectations (prognosis)

Most symptoms of allergies to mold, dander, and dust can be readily treated, and regular treatment can minimize the symptoms.

In some cases (particularly in children), people may outgrow an allergy as the immune system becomes less sensitive to the allergen. However, as a general rule, once a substance causes allergies for an individual, it can continue to affect the person long term.

The most severe cases of allergic rhinitis from these allergens may require allergy shots.

Complications

Anaphylaxis (a rare but severe allergic reaction)
Drowsiness and other side effects of antihistamines
Frequent ear infections (otitis media) in children
Hives or other skin rashes
Sinus infections

Calling your health care provider

Call your health care provider if severe symptoms of allergy occur, if previously successful treatment has become ineffective, or if symptoms do not respond to treatment.

Prevention

Breastfeeding can help prevent and decrease allergies. There is also evidence that exposures to certain allergens in the first year of life may prevent some allergies.

Mold spores are everywhere. You can reduce your exposure to mold by following these steps:

Keep rooms dry, and use a dehumidifier, if necessary.
Throw out moldy or mildewed articles (such as books, toys, and shoes).
Use synthetic fabrics for clothing and household furnishings whenever possible. Disinfect bathrooms, basement walls, and furniture with diluted bleach or other disinfectant solutions.

You can take several steps to limit exposure to dust mites.

Wrap mattresses, box springs, and pillows with mite-proof covers.
Wash bedding and pillows once a week in hot water (130° F to 140° F).
If you can, get rid of upholstered furniture. Try to use wooden, leather, or vinyl.
Keep indoor air dry. Try to keep the humidity level lower than 50%.
Wipe dust with a damp cloth and vacuum once a week. Use a vacuum cleaner with a HEPA filter.
Replace wall-to-wall carpet with wood or other hard flooring.
Keep stuffed toys off the beds, and wash them weekly.
Replace slatted blinds and cloth draperies with pull-down shades. They will not collect as much dust.
Keep closets clean, and keep closet doors closed.

Central heating and air-conditioning systems may be helpful, particularly if they include special filters to capture dust and animal dander. Change furnace filters frequently. Use of high efficiency particulate air (HEPA) filters are most helpful in preventing mold exposures.

People who are allergic to animals may need to avoid keeping pets. If not, keep pets outside, if possible. If pets are allowed indoors, keep them out of bedrooms, off upholstered furniture, and off carpets. Frequent bathing and grooming of the pet (preferably by someone who is not allergic to the animal) may help.

Allergy to animals may also include wool, which may contain tiny amounts of dander (skin).

References

Bahls C. In the clinic. Allergic rhinitis. Ann Intern Med. 2007 Apr 3;146(7):ITC4-1-ITC4-16. [PubMed]

Sheikh A, Hurwitz B, Shehata Y. House dust mite avoidance measures for perennial allergic rhinitis. Cochrane Database Syst Rev. 2007 Jan 24;(1):CD001563. [PubMed]

Wallace DV, Dykewicz MS, Bernstein DI, Blessing-Moore J, Cox L, Khan DA, et al. The diagnosis and management of rhinitis: an updated practice parameter. J Allergy Clin Immunol. 2008 Aug:122(2). [PubMed]

Review Date: 6/29/2010.

Reviewed by: Paula J. Busse, MD, Assistant Professor of Medicine, Division of Clinical Immunology, Mount Sinai School of Medicine, New York, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Allergy symptoms

The immune system normally responds to harmful substances such as bacteria, viruses and toxins by producing symptoms such as runny nose and congestion, post-nasal drip and sore throat, and itchy ears and eyes. An allergic reaction can produce the same symptoms in response to substances that are generally harmless, like dust, dander or pollen. The sensitized immune system produces antibodies to these allergens, which cause chemicals called histamines to be released into the bloodstream, causing itching, swelling of affected tissues, mucus production, hives, rashes, and other symptoms. Symptoms vary in severity from person to person.

Review Date: 6/29/2010.

Dust mite-proof pillow cover

To help decrease the amount of dust mites encase mattresses, box springs, and pillows with mite-proof covers. Further methods consist of washing bedding once a week in hot water, and dusting with a wet cloth once a week. Carpets can be a significant source of dust mites and should be vacuumed weekly with a vacuum cleaner containing a HEPA filter. Wooden and leather furniture is also another way to reduce the dust mite population in the home.

Review Date: 6/29/2010.

HEPA air filter

A HEPA (High Efficiency Particle Arresting) filter can remove the majority of harmful particles, including mold spores, dust, dust mites, pet dander and other irritating allergens from the air. Along with other methods to reduce allergens, such as frequent dusting, the use of a HEPA filtration system can be a helpful aid in controlling the amount of allergens circulating in the air. HEPA filters can be found in most air purifiers, which are usually small and portable.

Review Date: 6/29/2010.

Yeast and mold

Mold and yeast are two groups of plants in the fungus family. Both groups can cause allergic reactions. Fungal spores can circulate in the air and may cause allergic rhinitis when inhaled.

Review Date: 6/29/2010.

Allergy testing

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Allergy tests are any of several tests used to determine the substances to which a person is allergic.

How the test is performed

There are many methods of allergy testing. Among the more common are:

Skin tests
Elimination-type tests
Blood tests (including the radioallergosorbent, or RAST, test)

SKIN TESTS

Skin tests are the most common. Specific methods vary.

One of the most common methods is the prick test. This test involves placing a small amount of suspected allergy-causing substances on the skin, usually the forearm, upper arm, or the back. Then, the skin is pricked so the allergen goes under the skin's surface. The health care provider closely watches the skin for signs of a reaction, usually swelling and redness of the site. Results are usually seen within 15-20 minutes. Several allergens can be tested at the same time.

A similar method involves injecting a small amount of allergen into the skin and watching for a reaction at the site. This is called an intradermal skin test. It is more likely to be used when testing is being done to find out if you are allergy to something specific, such as bee venom or penicillin.

Patch testing is a method to diagnose allergic reactions on the skin. Possible allergens are taped to the skin for 48 hours. The health care provider will look at the area in 24 hours, and then again 48 hours later.

Skin tests are most useful for diagnosing:

Food allergy
Mold, pollen, animal, and other allergies that cause allergic rhinitis and asthma
Penicillin allergy*
Venom allergy
Allergic contact dermatitis

ELIMINATION TESTS

An elimination diet can be used to check for food allergies. An elimination diet is one in which foods that may be causing symptoms are removed from the diet for several weeks and then slowly re-introduced one at a time while the person is watched for signs of an allergic reaction.

BLOOD TESTS

Blood tests can be done to measure the amount of immunoglobulin (Ig) E antibodies to a specific allergen in the blood. This test may be used when skin testing is not helpful or cannot be done

Other blood tests include:

Absolute eosinophil count
Total IgE level

PROVOCATION

Provocation (challenge) testing involves exposing a person to a suspected allergen under controlled circumstances. This may be done in the diet or by breathing in the suspected allergen. This type of test may provoke severe allergic reactions. Challenge testing should only be done by a doctor.

Another method is the double-blind test. This method involves giving foods and harmless substances in a disguised form. The person being tested and the provider are both unaware of whether the substance tested in that session is the harmless substance or the suspected food. A third party knows the identity of the substances and identifies them with some sort of code. This test requires several sessions if more than one substance is under investigation.

While the double-blind strategy is useful and practical for mild allergic reactions, it must be done carefully in individuals with suspected severe reactions to foods. Blood tests may be a safer first approach.

How to prepare for the test

Before any allergy testing, the health care provider will ask for a very detailed medical history. This may include questions about such things as illnesses, emotional and social conditions, work, entertainment, lifestyle, foods, and eating habits.

If skin testing will be performed, you should NOT take antihistamines before the test. This may lead to a false-negative result, falsely reassuring you that a substance is unlikely to cause a severe allergic reaction. Your doctor will tell you which medicines to avoid and when to stop taking them before the test.

How the test will feel

Skin tests may cause very mild discomfort when the skin is pricked. Itching may occur if you have a positive reaction to the allergen.

Why the test is performed

Allergy tests are done to determine the specific substances that cause an allergic reaction in a person.

Your doctor may order allergy tests if you have:

Allergic rhinitis and asthma symptoms that are not easily controlled with medications
Angioedema and hives
Food allergies
Contact dermatitis
Penicillin allergy*

*NOTE: Allergies to penicillin and closely related medications are the only drug allergies that can be tested using skin tests. Skin tests for allergies to other drugs can be dangerous.

The prick skin test may also be used to diagnose food allergies. Intradermal tests are not used to test for food allergies because of high false positive results and the danger of causing a severe allergic reaction.

Normal Values

In a nonallergic person, allergy tests should be negative (no response to the allergen).

What abnormal results mean

A positive result means you reacted to a specific substance. Often, but not always, a positive result means the symptoms that you are having are due to exposure to the substance in question. In general, a stronger response means you are more sensitive to the substance.

People can have a positive response with allergy skin testing, but not have any problems with the specific substance in every day life.

The skin tests are generally reliable. However, if the dose of allergen is excessive, a positive reaction will occur even in persons who are not allergic.

What the risks are

Risks related to skin and food allergy tests may include:

Allergic reaction
Life-threatening anaphylactic reaction

Special considerations

The accuracy of allergy testing varies quite a bit. Even the same test performed at different times on a person may give different results. A person may react to a substance during testing, but never react during normal exposure. Rarely, a person may also have a negative allergy test and still be allergic to the substance.

References

Bernstein IL, Li JT, Bernstein DI, Hamilton R, et al. American Academy of Allergy, Asthma and Immunology; American College of Allergy, Asthma and Immunology. Allergy diagnostic testing: an updated practice parameter. Ann Allergy Asthma Immunol. 2008 Mar;100(3 Suppl 3):S1-148.

Demoly P, Bousquet J, Romano A. In vivo methods for the study of allergy. In: Adkinson NF Jr, ed. Middleton’s Allergy: Principles and Practice. 7th ed. Philadelphia, Pa: Mosby Elsevier; 2008:chap 71.

Gober MD, DeCapite TJ, Gaspari AA. Contact dermatitis. In: Adkinson NF Jr, ed. Middleton’s Allergy: Principles and Practice. 7th ed. Philadelphia, Pa: Mosby Elsevier; 2008:chap 63.

Review Date: 6/29/2010.

RAST test

The RAST (Radioallergosorbent test) is a laboratory test performed on blood. It tests for the amount of specific IgE antibodies in the blood which are present if there is a "true" allergic reaction.

Review Date: 6/29/2010.

Allergy skin prick or scratch test

One of the most common methods of allergy testing is the scratch test or skin prick test. The test involves placing a small amount of the suspected allergy-causing substance (allergen) on the skin (usually the forearm, upper arm, or the back), and then scratching or pricking the skin so that the allergen is introduced under the skin surface. The skin is observed closely for signs of a reaction, which usually includes swelling and redness of the site. With this test, several suspected allergens can be tested at the same time, and results are usually obtained within about 20 minutes.

Review Date: 6/29/2010.

Intradermal allergy test reactions

Intradermal allergy testing is another method of skin testing to help determine whether an individual is allergic to a specific allergen. The test involves injection of a small amount of the suspected allergen under the surface of the skin. After about 20 minutes the area is examined for a reaction at the site. A typical reaction looks like a small hive with swelling and redness. The intradermal test is more sensitive than the skin prick test and can usually provide more consistent results.

Review Date: 6/29/2010.

Skin testing, PPD (R arm) and Candida (L)

The right arm represents a positive reaction to PPD (a skin test for tuberculosis protein). The left arm represents a positive reaction to Candida protein. Candida antigen is tested to determine if the individual's immune system is functioning well; a normal immune system demonstrates a positive reaction.

Review Date: 6/29/2010.

Allergic reactions

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Allergic reactions are sensitivities to substances, called allergens, that come into contact with the skin, nose, eyes, respiratory tract, and gastrointestinal tract. They can be inhaled into the lungs, swallowed, or injected.

Considerations

Allergic reactions are common. The immune response that causes an allergic reaction is similar to the response that causes hay fever. Most reactions happen soon after contact with an allergen.

Many allergic reactions are mild, while others can be severe and life-threatening. They can be confined to a small area of the body, or they may affect the entire body. The most severe form is called anaphylaxis or anaphylactic shock. Allergic reactions occur more often in people who have a family history of allergies.

Substances that don't bother most people (such as venom from bee stings and certain foods, medications, and pollens) can trigger allergic reactions in certain people.

Although first-time exposure may only produce a mild reaction, repeated exposures may lead to more serious reactions. Once a person has had an exposure or an allergic reaction (is sensitized), even a very limited exposure to a very small amount of allergen can trigger a severe reaction.

Most severe allergic reactions occur within seconds or minutes after exposure to the allergen. However, some reactions can occur after several hours, particularly if the allergen causes a reaction after it has been eaten. In very rare cases, reactions develop after 24 hours.

Anaphylaxis is a sudden and severe allergic reaction that occurs within minutes of exposure. Immediate medical attention is needed for this condition. Without treatment, anaphylaxis can get worse very quickly and lead to death within 15 minutes.

Causes

Common allergens include:

Animal dander
Bee stings or stings from other insects
Foods, especially nuts, fish, and shellfish
Insect bites
Medications
Plants
Pollens

Symptoms

Common symptoms of a mild allergic reaction include:

Hives (especially over the neck and face)
Itching
Nasal congestion
Rashes
Watery, red eyes

Symptoms of a moderate or severe reaction include:

Cramps or pain in the abdomen
Chest discomfort or tightness
Diarrhea
Difficulty breathing
Difficulty swallowing
Dizziness or light-headedness
Fear or feeling of apprehension or anxiety
Flushing or redness of the face
Nausea and vomiting
Palpitations
Swelling of the face, eyes, or tongue
Weakness
Wheezing
Unconsciousness

First Aid

For a mild to moderate reaction:

Calm and reassure the person having the reaction, as anxiety can worsen symptoms.

Try to identify the allergen and have the person avoid further contact with it. If the allergic reaction is from a bee sting, scrape the stinger off the skin with something firm (such as a fingernail or plastic credit card). Do not use tweezers; squeezing the stinger will release more venom.
If the person develops an itchy rash, apply cool compresses and over-the-counter hydrocortisone cream.
Watch the person for signs of increasing distress.
Get medical help. For a mild reaction, a physician may recommend over-the-counter medications (such as antihistamines).

For a severe allergic reaction (anaphylaxis):

Check the person's airway, breathing, and circulation (the ABC's of Basic Life Support). A warning sign of dangerous throat swelling is a very hoarse or whispered voice, or coarse sounds when the person is breathing in air. If necessary, begin rescue breathing and CPR.
Call 911.
Calm and reassure the person.
If the allergic reaction is from a bee sting, scrape the stinger off the skin with something firm (such as a fingernail or plastic credit card). Do not use tweezers -- squeezing the stinger will release more venom.
If the person has emergency allergy medication on hand, help the person take or inject the medication. Avoid oral medication if the person is having difficulty breathing.
Take steps to prevent shock. Have the person lie flat, raise the person's feet about 12 inches, and cover him or her with a coat or blanket. Do NOT place the person in this position if a head, neck, back, or leg injury is suspected or if it causes discomfort.

Do Not

Do NOT assume that any allergy shots the person has already received will provide complete protection.
Do NOT place a pillow under the person's head if he or she is having trouble breathing. This can block the airways.
Do NOT give the person anything by mouth if the person is having trouble breathing.

Call immediately for emergency medical assistance if

Call for immediate medical emergency assistance if:

The person is having a severe allergic reaction -- always call 911. Do not wait to see if the reaction is getting worse.
The person has a history of severe allergic reactions (check for a medical ID tag).

Prevention

Avoid triggers such as foods and medications that have caused an allergic reaction (even a mild one) in the past. Ask detailed questions about ingredients when you are eating away from home. Carefully examine ingredient labels.
If you have a child who is allergic to certain foods, introduce one new food at a time in small amounts so you can recognize an allergic reaction.
People who know that they have had serious allergic reactions should wear a medical ID tag.
If you have a history of serious allergic reactions, carry emergency medications (such as a chewable form of diphenhydramine and injectable epinephrine or a bee sting kit) according to your health care provider's instructions.
Do not use your injectable epinephrine on anyone else. They may have a condition (such as a heart problem) that could be negatively affected by this drug.

References

Schwartz LB. Systemic anaphylaxis, food allergy, and insect sting allergy. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 274.

Wasserman SI. Approach to the person with allergic or immunologic disease. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 270.

Review Date: 5/2/2010.

Reviewed by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Stuart I. Henochowicz, MD, FACP, Associate Clinical Professor of Medicine, Division of Allergy, Immunology, and Rheumatology, Georgetown University Medical School. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Allergic reactions

Allergic reaction can be provoked by skin contact with poison plants, chemicals and animal scratches, as well as by insect stings. Ingesting or inhaling substances like pollen, animal dander, molds and mildew, dust, nuts and shellfish, may also cause allergic reaction. Medications such as penicillin and other antibiotics are also to be taken with care, to assure an allergic reflex is not triggered.

Review Date: 10/28/2010.

Reviewed by: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Dermatographism - close-up

Dermatographism is a condition where lightly scratching the skin raises wheals or welts. Histamine is released, which causes the small blood vessels (capillaries) to dilate, producing redness and localized swelling.

Review Date: 10/10/2010.

Dermatographism on the arm

Dermatographism is a condition where lightly scratching the skin raises wheals or welts. Histamine is released at the site, causing the small blood vessels (capillaries) to dilate, producing redness and localized swelling.

Review Date: 10/10/2010.

Hives (urticaria) on the arm

Hives (urticaria) are raised, red, itchy welts, seen here on the arm. The majority of urticaria develop as a result of allergic reactions. Occasionally, they may be associated with autoimmune diseases, infections (parasitosis), drugs, malignancy, or other causes.

Review Date: 6/29/2010.

Reviewed by: Paula J. Busse, MD, Assistant Professor of Medicine, Division of Clinical Immunology, Mount Sinai School of Medicine, New York, NY. Review provided by VeriMed Healthcare Network. David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Hives (urticaria) on the chest

Hives (urticaria) are raised, red, itchy welts, seen here on the chest. The majority of urticaria develop as a result of allergic reactions. Occasionally they may be associated with autoimmune diseases, infections (parasitosis), drugs, malignancy, or other causes.

Review Date: 6/29/2010.

Reviewed by: Paula J. Busse, MD, Assistant Professor of Medicine, Division of Clinical Immunology, Mount Sinai School of Medicine, New York, NY. Review provided by VeriMed Healthcare Network. David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Hives (urticaria) - close-up

Hives (urticaria) are raised, red, itchy welts. The majority of urticaria develop as a result of allergic reactions. Occasionally, they may be associated with autoimmune diseases, infections (parasitosis), drugs, malignancy, or other causes.

Review Date: 6/29/2010.

Reviewed by: Paula J. Busse, MD, Assistant Professor of Medicine, Division of Clinical Immunology, Mount Sinai School of Medicine, New York, NY. Review provided by VeriMed Healthcare Network. David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Hives (urticaria) on the trunk

This person has raised, red, itchy welts (urticaria) on the chest and abdomen. The majority of urticaria develop as a result of allergic reactions. Occasionally, they may be associated with autoimmune diseases, infections (parasitosis), drugs, malignancy, or other causes.

Review Date: 5/25/2009.

Reviewed by: Stuart I. Henochowicz, MD, FACP, Associate Clinical Professor of Medicine, Division of Allergy, Immunology, and Rheumatology, Georgetown University Medical School. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Dermatographism on the back

In dermatographism, hives are readily produced if the skin is lightly scratched.

Review Date: 10/10/2010.

Dermatographism - arm

Wheal formation at the site of light scratching of the skin.

Review Date: 5/2/2010.

Allergic reactions

Allergic reaction is a sensitivity to a specific substance, called an allergen, that is contacted through the skin, inhaled into the lungs, swallowed or injected. The body's reaction to an allergen can be mild, such as a localized rash, or life-threatening, such as anaphylactic shock.

Review Date: 5/2/2010.

Allergic conjunctivitis

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Causes, incidence, and risk factors

When your eyes are exposed to anything to which you are allergic, histamine is released and the blood vessels in the conjunctiva become swollen (the conjunctiva is the clear membrane that covers the "white" of the eye). Reddening of the eyes develops quickly and is accompanied by itching and tearing.

Allergies tend to run in families, although no obvious mode of inheritance is recognized. The incidence of allergy is difficult to determine, because many different conditions are often lumped under the term allergy. Keep in mind that rubbing the eyes makes the situation worse.

Symptoms

Symptoms may be seasonal and can include:

Red eyes
Dilated vessels in the clear tissue covering the white of the eye
Intense itching or burning eyes
Puffy eyelids, especially in the morning
Tearing (watery eyes)
Stringy eye discharge

Signs and tests

Your doctor may look for the following:

Certain white blood cells, called eosinophils, in scrapings, secretions, or discharge
Small, raised bumps on the inside of the eyelids (papillary conjunctivitis)
Positive skin test for suspected allergens (See: Allergy testing)

Treatment

The best treatment is avoiding exposure to the cause or allergen. Unfortunately, this is not often practical. Discomfort can be relieved by applying cool compresses to the eyes or taking antihistamines by mouth (many of these are available over the counter).

If home-care measures do not help, treatment by the health care provider may be necessary. This may include:

Antihistamine or anti-inflammatory drops that are placed into the eye
Mild eye steroid preparations applied directly on the surface of the eye (for severe reactions)
Eye drops that prevent certain white blood cells called mast cells from releasing histamine; these drops are given in combination with antihistamines for moderate to severe reactions

Expectations (prognosis)

Treatment usually relieves the symptoms. However, the condition tends to recur if exposure to the offending agent continues.

Complications

There are no serious complications; persistent discomfort is common.

Calling your health care provider

Call for an appointment with your health care provider if you experience allergic conjunctivitis and it is unresponsive to over-the-counter treatment.

Prevention

Prevention of allergic conjunctivitis is best accomplished by avoiding the allergen, if it is known. In many cases, however, this is impossible since the allergy-causing agents are everywhere nearly all the time.

References

Bielory L, Friedlaender MH. Allergic conjunctivitis. Immunol Allergy Clin North Am. 2008;28(1):43-58. [PubMed]

Review Date: 8/22/2008.

Reviewed by: Paul B. Griggs, MD, Department of Ophthalmology, Virginia Mason Medical Center, Seattle, WA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Eye

The eye is the organ of sight, a nearly spherical hollow globe filled with fluids (humors). The outer layer or tunic (sclera, or white, and cornea) is fibrous and protective. The middle tunic layer (choroid, ciliary body and the iris) is vascular. The innermost layer (the retina) is nervous or sensory. The fluids in the eye are divided by the lens into the vitreous humor (behind the lens) and the aqueous humor (in front of the lens). The lens itself is flexible and suspended by ligaments which allow it to change shape to focus light on the retina, which is composed of sensory neurons.

Review Date: 11/8/2010.

Reviewed by: Daniel E. Bustos, MD, MS, Private Practice specializing in Comprehensive Ophthalmology in Eugene, OR. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

Allergy symptoms

Review Date: 6/29/2010.

Conjunctivitis

Allergy-causing substances like pollen and dander may cause dilatation of blood vessels in the conjunctiva, the membrane covering the eye. The resulting reddening of the eyes is called allergic conjunctivitis, and is usually accompanied by itching and tearing.

Review Date: 8/22/2008.

Treatment

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Severe allergic reactions (anaphylaxis) require treatment with a medicine called epinephrine, which can be life saving when immediately given.

The best way to reduce symptoms is to try and avoid what causes your allergies in the first place. This is especially important for food and drug allergies.

There are several types of medications available to prevent and treat allergies. Which medicine your doctor recommends depends on the type and severity of your symptoms, your age, and overall health.

Specific illnesses that are caused by allergies (such as asthma, hay fever, and eczema) may require other treatments.

Medications that can be used to treat allergies include:

ANTIHISTAMINES

Antihistamines are available over-the-counter and by prescription. They are available in many forms, including:

Capsules and pills
Eye drops
Injection
Liquid
Nasal spray

CORTICOSTEROIDS

Anti-inflammatory medications (corticosteroids) are available in many forms, including:

Creams and ointment for the skin
Eye drops
Nasal spray
Lung inhaler

Patients with severe allergic symptoms may be prescribed corticosteroid pills or injections for short periods of time.

DECONGESTANTS

Decongestants can help relieve a stuffy nose. Decongestant nasal spray should not be used for more than several days, because they can cause a "rebound" effect and make the congestion worse. Decongestants in pill form do not cause this problem.

OTHER MEDICINES

Leukotriene inhibitors are medicines that specifically block the substances that trigger allergies. Zafirlukast (Accolate) and montelukast (Singulair) are approved for those with asthma and indoor and outdoor allergies.

ALLERGY SHOTS

Allergy shots (immunotherapy) are occasionally recommended if the allergen cannot be avoided and symptoms are hard to control. Allergy shots keep your body from over-reacting to the allergen. Regular injections of the allergen are given, with each dose slightly larger than the previous dose until a maximum dose is reached. They do not work for everybody and require frequent doctor's visits.

Signs and tests

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The health care provider will perform a physical exam and ask questions such as when the allergy occurs.

Allergy testing may be needed to determine if the symptoms are an actual allergy or caused by other problems. For example, eating contaminated food (food poisoning) may cause symptoms similar to food allergies. Some medications (such as aspirin and ampicillin) can produce non-allergic reactions, including rashes. A runny nose or cough may actually be due to an infection.

Skin testing is the most common method of allergy testing. One type of skin testing is the prick test. It involves placing a small amount of the suspected allergy-causing substances on the skin, and then slightly pricking the area so the substance moves under the skin. The skin is closely watched for signs of a reaction, which include swelling and redness. Skin testing may be an option for some young children and infants.

Other types of skin tests include patch testing and intradermal testing. For detailed information, see:Allergy testing

Blood tests can measure the levels of specific allergy-related substances, especially one called immunoglobulin E (IgE).

A complete blood count (CBC), specifically the eosinophil white blood cell count, may also help reveal allergies.

In some cases, the doctor may tell you to avoid certain items to see if you get better, or to use suspected items to see if you feel worse. This is called "use or elimination testing." This is often used to check for food or medication allergies.

The doctor may also check your reaction to physical triggers by apply heat, cold, or other stimulation to your body and watching for an allergic response.

Sometimes, a suspected allergen is dissolved and dropped into the lower eyelid to check for an allergic reaction. This should only be done by a health care provider.

Symptoms

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Allergy symptoms vary, but may include:

Breathing problems (coughing, shortness of breath)
Burning, tearing, or itchy eyes
Conjunctivitis (red, swollen eyes)
Coughing
Diarrhea
Headache
Hives
Itching of the nose, mouth, throat, skin, or any other area
Runny nose
Skin rashes
Stomach cramps
Vomiting
Wheezing

What part of the body is contacted by the allergen plays a role in the symptoms you develop. For example:

Allergens that are breathed in often cause a stuffy nose, itchy nose and throat, mucus production, cough, or wheezing
Allergens that touch the eyes may cause itchy, watery, red, swollen eyes.
Eating something you are allergic to can cause nausea, vomiting, abdominal pain, cramping, diarrhea, or a severe, life-threatening reaction
Allergens that touch the skin can cause a skin rash, hives, itching, blisters, or even skin peeling
Drug allergies usually involve the whole body and can lead to a variety of symptoms

Causes, incidence, and risk factors

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Allergies are relatively common. Both genetics and environmental factors play a role.

The immune system normally protects the body against harmful substances, such as bacteria and viruses. It also reacts to foreign substances called allergens, which are generally harmless and in most people do not cause a problem.

But in a person with allergies, the immune response is oversensitive. When it recognizes an allergen, it releases chemicals such as histamines. which fight off the allergen. This causes itching, swelling, mucus production, muscle spasms, hives, rashes, and other symptoms, which vary from person to person.

Common allergens include pollen, mold, pet dander, and dust. Food and drug allergies are common. Allergic reactions can also be caused by insect bites, jewelry, cosmetics, spices, and other substances.

Some people have allergy-like reactions to hot or cold temperatures, sunlight, or other environmental triggers. Sometimes, friction (rubbing or roughly stroking the skin) will cause symptoms.

A specific allergy is not usually passed down through families (inherited). However, if both your parents have allergies, you are likely to have allergies. The chance is greater if your mother has allergies.

Allergies may make certain medical conditions such as sinus problems, eczema, and asthma worse.

Allergies

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Allergy is an exaggerated immune response or reaction to substances that are generally not harmful. Allergy is caused by a highly sensitive immune system which leads to a misguided immune response. Normally, the immune system protects the body from harmful substances such as bacteria and viruses. An allergic reaction occurs when the immune system reacts to substances (allergens) that are usually harmless to which most people do not produce an immune response.

In a child with allergies, first exposure to an allergen stimulates the immune system to recognize the substance. Any subsequent exposure to allergens typically causes symptoms. When an allergen enters the body of a person who has the sensitized immune system, certain cells release histamine and other chemicals. This causes itching, swelling, mucus production, muscle spasms, hives, skin rash and other symptoms.

Allergies in Children — Symptoms

Symptoms vary in severity from one person to another. Most people have symptoms that not only cause the discomfort but also endanger their lives, while a few people have life-threatening reactions (called anaphylaxis).

The body part that comes into direct contact with the allergen influences the symptoms. For example, normally, inhaled allergens cause nasal congestion, itching in nose and throat, mucus production, coughing or wheezing. In general, food allergies can cause abdominal pain, cramping, diarrhea, nausea, vomiting or other severe life-threatening reactions. Often, any allergy to plants normally produces a rash and an allergic reaction to medications affects the whole body.

Allergy symptoms vary depending on what is causing the reaction and in which part of the body it occurs. Symptoms may include:

Increased tears, runny nose, burning or itching sensation in the eyes red eyes, conjunctivitis, edema of the eyes Itching in the nose, mouth, throat, skin or any other area, whistling cough difficulty breathing, Urticaria (hives on the skin) eruption, colic skin, headache, vomiting and diarrhea.

Some diseases are related to allergies such as eczema and asthma, among many others.

Common allergens include environmental agents that have contact with the skin, airways or on the surface of the eye (such as pollen, dander and dust). Similarly, allergic reactions can be caused by insect bites, jewelry, cosmetics, and almost any substance that has contact with the body.

Some people have a kind of allergic reaction to cold or warm temperatures, sun or other physical stimuli, and some friction (rubbing or blows to the skin) symptoms. Allergies are relatively common and it has been found that factors such as heredity and environmental conditions play a role in allergies.

Source: Health Guidance