Fixed eruptions: causative drugs and challenge tests.

The drugs responsible for eighty-six cases of fixed drug eruption have been identified, and in all but two were confirmed by challenge. The series included sixteen cases of generalized bullous fixed eruption, which resembles Lyell's syndrome. The main causative drugs were phenazones and barbiturates, both in the series as a whole and in the group of the most severe cases. The same drugs were the most frequent causative agents in a report from Finland 10 years ago.