Cimetidine

What it is and how it works

Mechanism class: Histamine H2 Receptor Antagonists

Indications

INDICATIONS AND USAGE Cimetidine tablets USP are indicated in: Short-term treatment of active duodenal ulcer. Most patients heal within 4 weeks and there is rarely reason to use cimetidine at full dosage for longer than 6 to 8 weeks (see DOSAGE AND ADMINISTRATION , Duodenal Ulcer ). Concomitant antacids should be given as needed for relief of pain. However, simultaneous administration of oral cimetidine and antacids is not recommended, since antacids have been reported to interfere with the absorption of oral cimetidine. Maintenance therapy for duodenal ulcer patients at reduced dosage after healing of active ulcer. Patients have been maintained on continued treatment with cimetidine 400 mg at bedtime for periods of up to five years. Short-term treatment of active benign gastric ulcer. There is no information concerning usefulness of treatment periods of longer than 8 weeks. Erosive gastroesophageal reflux disease (GERD). Erosive esophagitis diagnosed by endoscopy. Treatment is indicated for 12 weeks for healing of lesions and control of symptoms.

Dosage and administration (summary)

DOSAGE AND ADMINISTRATION Duodenal Ulcer Active Duodenal Ulcer Clinical studies have indicated that suppression of nocturnal acid is the most important factor in duodenal ulcer healing (see CLINICAL PHARMACOLOGY , Acid Secretion ). This is supported by recent clinical trials (see Clinical Trials , Active duodenal ulcer ). Therefore, there is no apparent rationale, except for familiarity with use, for treating with anything other than a once-daily at bedtime oral dosage regimen. In a U.S. oral dose-ranging study of 400 mg at bedtime, 800 mg at bedtime and 1600 mg at bedtime, a continuous dose response relationship for ulcer healing was demonstrated.

Contraindications

CONTRAINDICATIONS Cimetidine is contraindicated for patients known to have hypersensitivity to the product.

Pregnancy

Pregnancy Teratogenic Effects Pregnancy category B Reproduction studies have been performed in rats, rabbits and mice at doses up to 40 times the normal human dose and have revealed no evidence of impaired fertility or harm to the fetus due to cimetidine. There are, however, no adequate and well-controlled studies in pregnant women.

Storage and supply

HOW SUPPLIED Cimetidine tablets USP, 300 mg are dark-green, oval-shaped, film-coated tablets, debossed with N192 on one side and 300 on the reverse. They are supplied as follows: NDC: 63629-1783-1 30 Tablets in a bottle. NDC: 63629-1783-2 60 Tablets in a bottle. NDC: 63629-1783-3 20 Tablets in a bottle. NDC: 63629-1783-4 21 Tablets in a bottle.

Source: Cimetidine (Cimetidine) — US FDA prescribing information, 2026-03-09, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.