H2 blockers

H2 blockers are medicines that work by reducing the amount of stomach acid secreted by glands in the lining of your stomach.

H2 blockers are used to:

There are different names and brands of H2 blockers. All are available over the counter without a prescription. Most work equally as well. Side effects may vary from drug to drug.

H2 blockers are most often taken by mouth. You can get them in the form of tablets, liquids, or capsules.

H2 blockers may be bought in lower doses at the store without a prescription. If you find yourself taking these most days for 2 weeks or more for acid reflux symptoms, make sure you see your health care provider about your symptoms.

If you have a peptic ulcer, your provider may prescribe H2 blockers along with 2 or 3 other medicines for up to 2 weeks.

If your provider prescribed these medicines for you:

Side effects from H2 blockers are rare.

If you are breastfeeding or pregnant, talk to your provider before taking these medicines. If you have kidney problems, do not use famotidine without talking to your provider.

Tell your provider about other medicines you are taking. H2 blockers may change the way certain drugs work. This problem is less likely with cimetidine and nizatidine.

Call your provider if:

Katz PO, Dunbar KB, Schnoll-Sussman FH, Greer KB, Yadlapati R, Spechler SJ. ACG clinical guideline for the diagnosis and management of gastroesophageal reflux disease. Am J Gastroenterol. 2022;117(1):27-56. PMID: 34807007 pubmed.ncbi.nlm.nih.gov/34807007/.

Richter JE, Vaezi MF. Gastroesophageal reflux disease. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 11th ed. Philadelphia, PA: Elsevier; 2021:chap 46.

Waller DG. Dyspepsia, peptic ulcer disease, and gastroesophageal reflux disease. In: Waller DG, Sampson A, Hitchings A, eds. Medical Pharmacology and Therapeutics. 6th ed. Philadelphia, PA: Elsevier; 2022:chap 33.



Review Date: 5/3/2023
Reviewed By: Michael M. Phillips, MD, Emeritus Professor of Medicine, The George Washington University School of Medicine, Washington, DC. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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