• Type: H2 blocker
  • Dosage Forms: 200, 300, 400, 800mg
  • Common Trade Names: Tagamet HB 200

Adult Dosing

Duodenal Ulcer, Active

  • 800mg PO QHS x 4-8 weeks

Duodenal Ulcer, Maintenance

  • 400mg PO QHS

Gastric Ulcer, active benign

  • 800mg PO QHS x 6 weeks

H. Pylori Infection

  • 400mg PO BID x 10-28 days

Pediatric Dosing


  • Neonates: 5- 10mg/kg/day PO divided q8-12h
  • Infants: 10-20mg/kg/day PO divided q8-12h
  • Children: 20-40mg/kg/day PO divided q6H

Special Populations

  • Pregnancy Rating: B (animal studies show no risk for adverse fetal effects, human fetal harm possible but unlikely)
  • Lactation: Probably Safe
  • Renal Dosing
    • Adult: CrCL 10-50: decrease dose 50%, CrCl <10, decrease dose 75%
    • Pediatric: CrCl 20-40, decrease dose 25% or give q8h, CrCL <20: decrease dose 50%
  • Hepatic Dosing
    • Adult: Not Defined
    • Pediatric not defined


  • Allergy to class/drug
  • caution if renal impairment
  • caution if hepatic impairment
  • caution in elderly patients
  • caution if chronic pulmonary disease
  • caution if DM
  • caution if immunocompromised

Adverse Reactions




  • Half-life: 2H
  • Metabolism: Liver; CYP450, 1A2, 2C19, 2D6 Inhibitor
  • Excretion: urine
  • Mechanism of Action: Histamine H2 Receptor blocker

See Also


  • 2019 American Geriatrics Society Beers Criteria Update Expert Panel. American Geriatrics Society 2019 Updated AGS Beers Criteria for Potentially Inappropriate Medication Use in Older Adults. J Am Geriatr Soc. 2019;67(4):674-694. doi: 10.1111/jgs.15767. [PubMed 30693946]
  • American Society of Anesthesiologists Task Force on Obstetric Anesthesia. Practice guidelines for obstetric anesthesia: an updated report by the American Society of Anesthesiologists Task Force on Obstetric Anesthesia. Anesthesiology. 2007;106(4):843-863. [PubMed 17413923]
  • Andreev E, Koopman M, Arisz L. A rise in plasma creatinine that is not a sign of renal failure: which drugs can be responsible? J Intern Med. 1999;246(3):247-252. [PubMed 10475992]
  • ASHP Therapeutic Guidelines on Stress Ulcer Prophylaxis. ASHP Commission on Therapeutics and approved by the ASHP Board of Directors on November 14, 1998. Am J Health Syst Pharm. 1999;56(4):347-379. [PubMed 10690219]
  • Aronoff GR, Bennett WM, Berns JS, et al, eds. Drug Prescribing in Renal Failure: Dosing Guidelines for Adults and Children. 5th ed. Philadelphia, PA: American College of Physicians; 2007.