Ninety-eight patients having fixed drug eruptions were subjected to provocation tests. Cutaneous involvement was seen in 43, mucous membrane in 33 patients, while cutaneous and mucous membrane involvement was seen in 22 patients. The causative drugs were found to be trimethoprim-sulphamethoxazole (45), acetylsalicylic acid (24), hyoscine butylbromide (Buscopan®) (8), ibuprofen (Brufen®) (6), oxyphenbutazone (6), tetracycline hydrochloride (2), phenolphthalein (1) and phenobarbitone (1). There was evidence of cross-sensitivity between oxyphenbutazone and phenylbutazon