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Name: Cimetidine

Pregnancy Category B

Drug classes

  • H2 antagonist

Therapeutic actions

Inhibits the action of histamine at the histamine2 (H2) receptors of the stomach, inhibiting gastric acid secretion and reducing total pepsin output.


  • Short-term treatment of active duodenal ulcer
  • Short-term treatment of benign gastric ulcer
  • Treatment of pathologic hypersecretory conditions (eg, Zollinger-Ellison syndrome)
  • Prophylaxis of stress-induced ulcers and acute upper GI bleed in critically ill patients
  • Treatment of erosive gastroesophageal reflux


  • Allergy to cimetidine, impaired renal or hepatic function, lactation.

Adverse effects

  • CNS: Dizziness, somnolence, headache, confusion, hallucinations, peripheral neuropathy; symptoms of brain stem dysfunction (dysarthria, ataxia, diplopia)
  • GI: Diarrhea
  • CV: Cardiac arrhythmias, arrest; hypotension (IV use)
  • Hematologic: Increases in plasma creatinine, serum transaminase
  • Other: Impotence (reversible with drug withdrawal), gynecomastia (in long-term treatment), rash, vasculitis, pain at IM injection site

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