Drugs causing fixed eruptions.

Forty patients having fixed drug eruptions were subjected to provocation tests. Twelve patients failed to complete the provocation tests while in the remaining, the causative drugs were shown to be tetracyclines (6), analgin (metamizole) (6), oxyphenbutazone (5), phenobarbitone (4), sulphadiazine (3), sulphaphenazole (2), penicillin (1), suphadimethoxone (1), Saridon (1), sulphadimidine (1) and sulphamethoxypryridazine (1). There was evidence of cross-sensitivity between tetracycline and demethylchlortetracycline and also between exyphenbutazone and phenylbutazone, but not between different sulphonamides, In 2 cases, the minimum dose of the drug capable of reactivating the lesions was 100 mg of sulphadiazine and 50 mg of Saridon respectively.