What to Know When Taking Tagamet

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Tagamet, or generically known as Cimetidine, is available in prescription and over-the-counter forms by the names Tagamet Tiltab, and Tagamet-HB. It is used to treat gastroesophageal reflux disease (GERD), esophagitis, and Zollinger-Ellison syndrome. Along with antibiotics, Tagamet is also used to treat peptic ulcers. Many doctors only prescribe prescription-strength H2 Blockers for the treatment of ulcer and esophagitis symptoms, while having their patients use over-the-counter forms for relief of symptoms of GERD, acid indigestion, and sour stomach.

How Tagamet Works

Tagamet is in a class of medications called H2 Blockers. The H2 stands for histamine-2, which is a naturally occurring chemical in the body that stimulates the production of acid by stomach cells. As the name suggests, drugs in this class, which also include Zantac, Axid, and Pepcid, decrease the amount of acid made in the stomach by blocking histamine.

Because of this mechanism, H2 blockers are not associated with the same risks as another heartburn medication class called PPIs or proton pump inhibitors.

What to Discuss With Your Doctor

Before taking any new medications there are numerous things that you should discuss with your doctor and pharmacist, such as:

  • What prescription and nonprescription medications or vitamins you are taking.
  • If you are allergic to Tagamet or any other drugs.
  • If you are pregnant, plan to become pregnant, or are breastfeeding. And on that note, if you become pregnant while taking Tagamet, call your doctor.
  • If you have a history of liver or kidney disease, human immunodeficiency virus (HIV), or acquired immunodeficiency syndrome (AIDS).

If you're taking antacids, be aware of the timing as they should be taken two hours before taking Tagamet. And if you should forget a Tagamet dose, contact your doctor before double dosing.

Your physician will be able to determine if it is safe to do so, or if you should wait until your next scheduled one.

Possible Side Effects

Tagamet may cause side effects, though they usually disappear after a few doses. If, however, any of the following symptoms are severe or do not go away, call your doctor:

  • Headache
  • Diarrhea
  • Dizziness
  • Drowsiness
  • Breast enlargement

The following symptoms are uncommon but can be serious. If you experience any of them, call your doctor immediately:

  • Confusion
  • Excitement
  • Depression
  • Nervousness
  • Seeing things or hearing voices that do not exist (hallucinating)

Call your doctor at any time if you experience any unusual problems while taking this medication.


"Understanding Some of the Medications Often Prescribed for GERD & Ulcers." Common GI Problems: Volume 1. American College of Gastroenterology. 24 Apr 2007.

Kenneth R. DeVault M.D., F.A.C.G., and Donald O. Castell M.D., M.A.C.G., "Updated Guidelines for the Diagnosis and Treatment of Gastroesophageal Reflux Disease." doi: 10.1111/j.1572-0241.2005.41217.x. American College of Gastroenterology. 24 Apr 2007.

"Effectiveness of Therapies for GERD" American College of Gastroenterology. 24 Apr 2007.