Evaluation of a worldwide spontaneous reporting system with cimetidine

Adverse reactions to cimetidine have been identified through the manufacturer's Worldwide Spontaneous Reporting System. Reactions not observed during clinical trials-mental confusion, interstitial nephritis, and potentiation of oral anticoagulants-were identified and added to the prescribing information for cimetidine while further studies were undertaken. The monitoring of the drug's adverse reaction profile is ongoing so that new types of reactions can be identified.