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Cimetidine

An acid-reducing (H2 blocker) tablet for ulcers and reflux disease.

Clinical information

Common uses

  • duodenal and stomach ulcers
  • erosive reflux disease (GERD)
  • conditions with excess stomach acid (e.g. Zollinger-Ellison syndrome)

Cautions

  • not for people allergic to cimetidine
  • affects how the liver clears many other medicines

Interactions

  • warfarin (blood thinner) — monitor clotting closely
  • phenytoin, theophylline and lidocaine — levels rise, adverse effects reported
  • diazepam, chlordiazepoxide, some tricyclic antidepressants — levels rise
  • propranolol, nifedipine and metronidazole — levels rise
  • ketoconazole — take at least 2 hours before cimetidine
  • antacids — do not take at the same time

Pregnancy: no harm in animal studies — use only if clearly needed

Reference information, not medical advice — always follow your doctor or pharmacist. Source: DailyMed, dailymed.nlm.nih.gov, cimetidine tablet label, setid 06c0a509-026f-44e0-9975-a94a8de51d43 (accessed 2026-08-16)

Approved brands & formulations1

Brand nameDosage formStrengthImporterCategory
CimetidineParenteral ( Injection )400 mg/2 mlPOM
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