IgE-mediated allergy to natural rubber in 30 patients with contact urticaria.

30 patients who had experienced contact urticaria after exposure to gloves, contraceptives, balloons or dental cofferdams went through a detailed examination including interviews on: exposure to rubber; local and distant symptoms; provocation tests; skin prick tests with (among other substances) latex extracts from the rubber tree Hevea brasiliensis; patch testing, IgE and RAST analyses. 23 patients (77%) reported additional symptoms from distant organs. 13 belonged to medical occupations; 25 were classified as atopics based on history; 21 had raised IgE-values; 25 were RAST-positive to the extracts from Hevea brasiliensis. 13 had a pre-existing hand dermatitis, of whom 6 were patch test positive to standard allergens. Skin prick tests with extracts from Hevea brasiliensis were the most sensitive diagnostic tool, while the RAST analysis was positive in 25/30 cases. These tests and analyses including RAST were negative in 40 control subjects. Provocation tests are of great value, but difficult to standardize. Several patients reported severe reactions at medical and dental examination/treatment situations (surgical gloves, dental cofferdams), and the risk of life-threatening anaphylactic reactions is emphasized.