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Famotidine

Brand names: Pepcid, Pepcid AC

Famotidine is an H2 blocker that lowers stomach acid. It treats and prevents heartburn and helps heal ulcers.

Brand namesPepcid, Pepcid AC
Type of medicineH2 blocker (acid reducer)
Prescription?Both prescription and over the counter
ImportantThis page is general information, not a prescription. Don't start, stop, or change a medicine without talking to your provider or pharmacist.

Overview

It starts working within an hour, but is less powerful than PPIs like omeprazole.

What it's used for

  • Heartburn and acid indigestion
  • Acid reflux (GERD)
  • Stomach and duodenal ulcers

How to take it

  • For heartburn, take it as needed or 15 to 60 minutes before food that causes heartburn.
  • Follow the label; don't use over-the-counter famotidine more than 14 days in a row without seeing a provider.

Your dose depends on your health and other medicines. Always follow your prescription label, and ask your pharmacist if anything is unclear.

Side effects

Common side effects

  • Headache
  • Constipation or diarrhea
  • Dizziness
Call 911Fast or irregular heartbeat or fainting
Call your provider todayConfusion or agitation, especially in older adults or with kidney disease

Warnings

  • See a provider if you have trouble swallowing, vomiting blood, black stools, or chest pain. These need checking.
  • Doses are lower with kidney disease.

Other medicines, foods, and alcohol

  • It lowers absorption of some medicines that need stomach acid, like certain antifungals and HIV medicines.

Tell your provider and pharmacist about every medicine, vitamin, and supplement you take.

Pregnancy and breastfeeding

Commonly used for heartburn in pregnancy when needed. Ask your provider.

Missed doses, overdose, and storage

If you miss a dose

This medicine is often taken only when needed. If you take it on a schedule, take a missed dose when you remember, unless it's almost time for the next one. Don't double up.

If someone takes too much

Call Poison Control at 1-800-222-1222 or get help online at poison.org. Call 911 if the person collapses, has a seizure, has trouble breathing, or can't be woken.

Storing it

Store at room temperature, away from heat and moisture (not in the bathroom), and out of reach of children and pets.

Conditions it's used for

Sources

Last updated 2026-11-13.