Does Tagamet HB (cimetidine) cause side effects?

Tagamet HB (cimetidine) is an H2 (histamine-2) blocker used to relieve heartburn associated with acid indigestion and sour stomach and to prevent heartburn brought on by eating or drinking certain foods and beverages

Tagamet HB blocks the production of acid by acid-producing cells in the stomach. Histamine is a naturally-occurring chemical that stimulates cells in the stomach (parietal cells) to produce acid. H2-blockers inhibit the action of histamine on the cells, thus reducing the production of acid by the stomach. 

Since excessive stomach acid can damage the esophagus, stomach, and duodenum by reflux and lead to inflammation and ulceration, reducing stomach acid prevents and allows acid-induced inflammation and ulcers to heal. 

Common side effects of Tagamet HB include

Serious side effects of Tagamet HB include

  • confusion and hallucinations (usually in elderly or critically ill patients),
  • enlargement of the breasts,
  • impotence (usually seen in patients on high doses for prolonged periods),
  • decreased white blood cell counts,
  • irregular heartbeat,
  • rash,
  • visual changes,
  • allergic reactions, and
  • hepatitis.

Drug interactions of Tagamet HB include cimetidine and warfarin, because Tagamet HB may increase the blood levels of these drugs by reducing their elimination by the liver.

There are no adequate studies of Tagamet HB in pregnant women. Tagamet HB is excreted in breast milk. Consult your doctor before breastfeeding

What are the important side effects of Tagamet HB (cimetidine)?

Side effects due to cimetidine are rare and generally reversible once the medication is stopped. Minor side effects include:

Major side effects include confusion and hallucinations (usually in elderly or critically ill patients), enlargement of the breasts; impotence (usually seen in patients on high doses for prolonged periods); decreased white blood cell counts.

Other side effects include:

  • irregular heartbeat,
  • rash,
  • visual changes,
  • allergic reactions, and
  • hepatitis.

Tagamet HB (cimetidine) side effects list for healthcare professionals

No information required

What drugs interact with Tagamet HB (cimetidine)?

No information required. See prescribing information.

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Medically Reviewed on 1/4/2021
References
FDA Prescribing Information

Professional side effects and drug interactions sections courtesy of the U.S. Food and Drug Administration.