[Severe confusion following a theophylline-cimetidine combination]

Cimetidine and theophylline were given together to a 67 year old chronic bronchitic post-operatively: the patient became very confused, shook of all his limbs, vomited, and presented a tachycardia. The greater than normal blood levels of theophylline (27.8 mg . 1(-1) confirmed its involvement in this clinical state. But, as there was no real overdose, the simultaneous administration of cimetidine was probably responsible for inducing this state. Three days after stopping this treatment, the disorder had completely disappeared.