What to Know When Taking Zantac

This over-the-counter H2 blocker could help relieve your heartburn

Doctor talking with patient in office
Doctor talking with patient in office. Terry Vine/Blend Images/Getty Images

Ads for the heartburn medication Zantac, also known by its generic name Ranitidine, feature a fireman. The symbol of extinguishing flames is an apt mascot for a medication that relieves the burning of acid reflux.

Sold over-the-counter as Zantac 75 and Maximum Strength Zantac 150, the numbers refer to the dosage amount in each tablet. Normally, it is prescribed by doctors for the treatment and prevention of acid indigestion-related heartburn, sour stomach, and relief of symptoms of GERD.

Many doctors only prescribe prescription-strength H2 Blockers for the treatment of peptic ulcersgastroesophageal reflux disease (GERD), esophagitis, and Zollinger-Ellison syndrome. 

After taking Zantac you should experience relief in 30 to 60 minutes, and it may last for up to 12 hours.

How Zantac Relieves Heartburn

Zantac is in a class of medications called H2 Blockers. It decreases the amount of acid made in the stomach by blocking histamine-2 (hence the H2), which is a naturally occurring chemical in the body that stimulates the production of acid by stomach cells. 

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

Prior to and While Taking Zantac, Talk to Your Doctor

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

  • Whether you're allergic to Zantac or any other drugs
  • What prescription and nonprescription medications or vitamins you are taking
  • If you are pregnant, plan to become pregnant, or are breastfeeding. If you become pregnant while taking Zantac, call your doctor
  • Any history of porphyria, phenylketonuria, kidney disease, or liver disease

    If you miss a dose, consult your physician before doubling up on your next dose. Your doctor will be able to determine if it is safe to do so, or if you should just wait and take your next scheduled dose. 

    Side Effects of Zantac

    Zantac may cause some side effects. For most people experiencing side effects, 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
    • Constipation
    • Upset stomach
    • Vomiting
    • Diarrhea
    • Stomach pain

    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

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