Skin manifestations in food allergy

Skin manifestations represent the most often observed clinical symptoms in food allergy. Immediate symptoms are urticaria, angioedema and sudden erythema (flush). Delayed symptoms which can be observed are exanthema and exacerbation or worsening of eczema (most often atopic dermatitis). Since delayed symptoms are difficult to diagnose, oral provocation tests are often necessary for patients with a suspected late onset of symptoms upon food ingestion. There is evidence that besides specific IgE, specific T cells play a role in the deterioration of eczema in atopic dermatitis. Although urticarial skin lesions are most often observed upon oral provocation with a suspected food, the rate of IgE-mediated food allergy in acute or chronic urticaria is rather low. In some patients suffering from chronic urticaria, intolerance reactions are also suspected. Since no laboratory or skin tests are available yet for the identification of clinically relevant food additives causing urticaria, oral provocation tests are mandatory for these patients.