Food Allergies and Your Skin
SKIN CONDITIONS AS AN ALLERGIC RESPONSE TO FOOD
URTICARIA - HIVES
The skin is a common target organ for allergic responses to food. Acute urticaria is characterized by pruritic, transient, erythematous raised lesions, sometimes accompanied by localized swelling (angioedema). Food allergy accounts for up to 20 percent of cases of acute urticaria and is mediated by IgE specific to food protein. Lesions usually occur within one hour after ingestion of or contact with the causal food. Because only 1.4 percent of cases of chronic or persistent urticaria (i.e., lasting more than six weeks) are caused by food allergy, a search for a causative food in the initial evaluation of this condition is not generally warranted.
Atopic dermatitis usually begins in early infancy and is characterized by a typical distribution (face, scalp and extremities), extreme pruritus and a chronic and relapsing course. This inflammatory skin condition is frequently associated with allergic disorders (e.g., asthma and allergic rhinitis) and with a family history of allergy. Evidence suggests that IgE-mediated food allergy plays a pathogenic role in atopic dermatitis, particularly in children, although non–IgE-mediated food allergy has also been implicated. Clinical studies using double-blind, placebo-controlled food challenges have shown that 37 percent of children with moderate atopic dermatitis have food allergy. By contrast, 6 to 8 percent of infants and children in the general population are allergic to some type of food.
Dermatitis herpetiformis is a chronic papulovesicular skin disorder in which lesions are distributed over the extensor surfaces of the elbows, knees and buttocks. The disorder is associated with a specific non–IgE-mediated immune sensitivity to gluten (a protein found in wheat, barley, oat and rye). Although dermatitis herpetiformis is related to celiac disease, patients often appear to have no associated gastrointestinal problems. The rash abates with the elimination of gluten from the diet.