Allergies affect more than half of all Americans, with 54 percent testing positive for at least one allergen, the American Academy of Allergy Asthma and Immunology (AAAAI) reports. Between 40 million and 50 million Americans have allergies that often result in skin rashes, ranging from mild and annoying to life threatening. Allergic skin rashes don't occur on the first exposure to a substance, but antibodies to the substance form and react the next time the allergen is encountered, MedlinePlus explains.
Causes
Many substances can cause an allergic skin reaction, which occurs when the offending substance, called an allergen, triggers physical responses in a body, which aims to rid the body of the substance, Rutgers University Health Service reports. Allergies that cause skin reactions can develop to food; materials that touch the skin, such as fabrics; perfumes; plants; and materials such as latex, inhaled substances and medications.
Types
Skin allergies can assume many different forms. Reactions to medications and foods often cause hives, raised welts that appear and disappear over a period of several days. Angioedema, which is severe swelling under the skin that often affects the areas around the eyes and mouth, commonly occurs in response to food and drug allergies, according to the AAAAI. Eczema, also known as atopic dermatitis, a skin rash that often affects small children, but can also affect adults, may run in families, Rutgers says, and often occurs in response to contact allergies. Plant allergies such as poison ivy often cause blistering on a reddened surface.
Symptoms
Besides the rash, many skin allergies produce itching, burning sensations; dry, thick, scaly rough skin; skin cracking or peeling; or swelling of the face that can constrict the airway and lead to life threatening shortness of breath.
Diagnosis
Skin allergy testing can diagnose specific allergies. Known as skin prick testing, allergy tests involve injecting a very tiny amount of allergen into the skin and watching for a reaction that indicates an allergy to a particular substance, the Merck Manual explains. Eliminating foods for one week to watch for improvement of symptoms may help diagnose a suspected food allergy.
Treatment
Mild skin allergic reactions usually clear up when the offending substance is removed. Severe itching responds to corticosteroid creams that reduce inflammation, cool compresses, calamine lotion or antihistamines taken by mouth. Severe reactions such as hives and angioedema, which can cause facial swelling, may require corticosteroid injections to reduce swelling and inflammation or, in severe cases of airway closure, epinephrine given by injection to open the airway.
Considerations
Most allergic skin reactions are best treated by avoiding the allergen. People with severe skin reactions to foods, plants and stinging insects such as bees should carry an epi pen, a self administered form of epinephrine, with them at all times. Severe allergy sufferers should also wear allergic bracelets or carry medical alert cards at all times to get help quickly, MedlinePlus suggests.
