Corticosteroid allergy.

Allergy to corticosteroids is becoming increasingly recognized. Diagnosis is difficult because of frequently false-negative patch tests. The optimum concentration and vehicle for patch testing with pure corticosteroid has still not been established. The patch test results of 19 patients with allergy to corticosteroids seen at the Skin and Cancer Foundation in Sydney, Australia, were analysed. It was found that patch testing with the patient's corticosteroid in the commercial cream base gave a greater yield of positive results than testing with the commercial corticosteroid ointment or with the pure corticosteroid in either petrolatum or in alcohol. Tixocortol pivalate, and to a lesser extent budesonide, were useful for detecting allergy to hydrocortisone, but not necessarily other corticosteroids. Delayed positive patch tests were often seen, showing the importance of carrying out a late reading. The repeat open application test (ROAT) with the patient's own corticosteroid was found to be a simple, useful diagnostic test.