Famotidine: Prescription, Warnings, Side Effects, Interactions and Dosage

Pepcid (by its brand name) is a medicine that reduces the amount of acid the stomach produces.

It is available as both prescription and over-the-counter (OTC) drugs.

Famotidine prescription

Pepcid is used to treat conditions such as:

  • Ulcers (sores on the lining of the stomach or small intestine).
  • Gastroesophageal reflux disease or GERD (when stomach acid irritates the esophagus, causing heartburn and other problems).
  • Certain tumors in the pancreas or Zollinger-Ellison syndrome.

Famotidine or Pepcid, sold over the counter, is used to help prevent and treat symptoms of heartburn, such as indigestion or an upset stomach after eating foods and drinking beverages that do not match your body.

Famotidine is in a class of medications called histamine-2 or H2 blockers, which work by reducing the amount of acid the stomach produces.

The others included ranitidine (Zantac), pantoprazole (Protonix), and omeprazole (Prilosec). They found that all but ranitidine suppressed acid secretion.


Your doctor may not prescribe or recommend famotidine if you have kidney problems.


Studies show that famotidine can adversely affect the central nervous system in people with moderate to severe kidney problems.

Pregnancy and famotidine

Animal studies have not found a risk to the developing fetus, but there are no adequate studies of the drug in pregnant women.

Ask your doctor if you can take this medicine if you are pregnant.

Studies have found that Pepcid is secreted in breast milk. If you are breastfeeding, you should discuss whether to discontinue breastfeeding or stop taking medicine with your doctor.

Side effects

The most frequently reported side effects by Pepcid users are:

Reports show that these side effects were rare. However, in a clinical trial, less than 5 percent of people had a headache, and less than 2 percent had dizziness, constipation, or diarrhea from taking Pepcid.

Severe side effects

Serious side effects are also rare. Those reported are heart rhythm problems, jaundice, liver enzyme abnormalities, facial swelling, and seizures.


Among the drugs that Pepcid may interact with are:

  • Atazanavir (Reyataz), an HIV / AIDS drug.
  • Tizanidine (Zanaflex), a muscle relaxant.
  • Naproxen (Aleve) and other pain relievers.

You should always tell your doctor about any prescription, non-prescription, over-the-counter (OTC), illegal, and recreational medications, herbal remedies, dietary and nutritional supplements, and all other medications and treatments that you are taking.

Pepcid and alcohol

Avoid drinking alcohol while taking Pepcid as it can harm your stomach.


Prescription: Famotidine comes as a tablet (20 mg or 40 mg) or a liquid to take by mouth. OTC famotidine is available in tablets, chewable tablets, or capsules.

Prescription famotidine dosages depend on the condition being treated. These are the recommended doses for some of its most common uses:

  • For duodenal ulcers, the usual dose is 40 mg a day at bedtime or 20 mg twice a day for 6 to 8 weeks, followed by a maintenance dose of about 20 mg at bedtime.
  • For benign gastric ulcers, the usual dose is 40 mg a day at bedtime.
  • For GERD, the usual dose is 20 mg twice a day for up to 6 weeks. If you have esophagitis (inflammation of the esophagus), the amount is usually 20 or 40 mg twice a day for up to 12 weeks.
  • For children under one year of age who have GERD, the usual starting dose is 0.5 mg for every kilogram (2.2 pounds) of body weight of oral Pepcid for up to 8 weeks. It is administered once a day to children under three months and twice a day to those over three months but less than a year.
  • For children with peptic ulcers between 1 and 16 years old, the dose is usually 0.5 mg per kg of body weight at bedtime or twice a day up to 40 mg a day.
  • For children 1 to 16 years of age with GERD, the dose is 1 mg per kg of body weight per day or divided twice a day up to 40 mg.


Do not take more prescription famotidine than recommended. Oral doses of up to 640 mg per day have been given to adults with conditions involving excess stomach acid without serious problems. However, you should follow the amounts recommended by your doctor.

Please do not take more than two famotidine tablets in 24 hours, and do not take it for more than two weeks unless recommended by your doctor.

If you use famotidine for two weeks and you still have symptoms of heartburn or indigestion, stop the medicine and call your doctor.

Missed dose

If you miss a dose, take it as soon as you remember, unless it is almost time for your next dose. If it is almost time for the next time, skip the missed dose and resume your regular medication schedule.