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Overview: Famotidine is used to treat heartburn, ulcers, and other conditions caused by too much stomach acid. It is available by prescription and over-the-counter (OTC). Famotidine is an H2 blocker that works by blocking certain histamine receptors in the body, which helps reduce the amount of acid your stomach makes. Common side effects include headache, dizziness, constipation, or diarrhea. Before using famotidine, tell your health care provider about any health conditions you have and all medicines you take.

Uses

What is famotidine used for?

Famotidine is commonly used for the following conditions.

These uses may vary depending on the specific famotidine product you are using.

Famotidine may also be used for other conditions as determined by your health care provider.

How does famotidine work (mechanism of action)?

Famotidine is in a family of medicines called H2 blockers. It works by blocking certain histamine receptors in the body, which helps reduce the amount of acid your stomach makes.

How is famotidine supplied (dosage forms)?

Brands and other names

  • Pepcid
  • Pepcid AC
  • Zantac 360

Dosage forms and strengths

  • 10 mg, 20 mg, 40 mg oral tablets
  • 40 mg/5 mL oral suspension

Famotidine is also available in injectable forms.

How should I store famotidine?

Oral Tablet. Famotidine tablet should be stored at room temperature, between 68 F and 77 F (20 C and 25 C). It can be exposed to temperatures between 59 F and 86 F (15 C and 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place. Protect from moisture.

Oral Liquid. Famotidine oral liquid should be stored at room temperature, between 68 F and 77 F (20 C and 25 C). It can be exposed to temperatures between 59 F and 86 F (15 C and 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place. Do not freeze it. Throw away the liquid after 30 days. 

Injection Liquid. Famotidine injection is usually given by a health care provider in a hospital or clinic. You will not store it at home.

Side Effects

What are the most common side effects of famotidine?

The most common side effects of famotidine are listed below. Tell your health care provider if you have any of these side effects that bother you.

  • Headache
  • Dizziness
  • Constipation
  • Diarrhea

There may be other side effects of famotidine that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of famotidine?

While less common, the most serious side effects of famotidine are described below, along with what to do if they happen.

Severe Allergic Reactions. Famotidine may cause allergic reactions, which can be serious. Stop taking famotidine and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Central Nervous System (CNS) Effects. Famotidine may affect your central nervous system (CNS). Some people have a higher risk of this, including people who are older or have kidney problems. Call your health care provider right away if you have the following symptoms of CNS effects.

  • Dizziness or sleepiness
  • Confusion or delirium
  • Feeling disoriented or agitated
  • Lack of energy
  • Seeing or hearing things that others do not see or hear, also called hallucinations
  • Changes in mood
  • Seizures

Warnings & Precautions

Who should not use famotidine?

Allergies to Ingredients. People who are allergic to any of the following should not use famotidine.

  • Famotidine
  • Pepcid
  • Pepcid AC
  • Zantac 360
  • Any other medicine known as an H2 blocker (also called an H2 receptor antagonist)
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific famotidine products they stock.

You should not take over-the-counter (OTC) famotidine if you have bloody or black poop, are vomiting blood, or have trouble or pain when swallowing food. Tell your health care provider right away if you have any of these symptoms.

What should I know about famotidine before using it?

If famotidine was prescribed to you by a health care provider, take it as prescribed. 

If you are taking over-the-counter (OTC) famotidine, read and follow the instructions that come with the product. Do not take OTC famotidine for more than 14 days without talking to your health care provider. Tell your health care provider if your symptoms do not get better or get worse.

Do not share famotidine that was prescribed for you by a health care provider with other people, even if they have the same condition as you. It may harm them.

Keep famotidine out of the reach of children.

If you are taking famotidine tablets, swallow them whole. Do not chew them.

If you are taking famotidine liquid, shake the bottle well for five to 10 seconds before measuring each dose. Use an accurate measuring device to measure your dose. A household spoon is not an accurate measuring device and may cause you to take the wrong dose. Ask your pharmacist to recommend an appropriate measuring device.

Antacids may be taken with famotidine if needed.

People who are 65 and older can be at greater risk of some side effects from famotidine. Talk to your health care provider about your risks if you are in this age group.

People with kidney problems can be at greater risk of certain side effects from famotidine, such as certain heart rhythm problems. Tell your health care provider right away if you feel lightheaded or faint or if you have changes in your heart rate or rhythm, such as a fast or skipping heartbeat.

Some famotidine products may have an ingredient called FD&C Yellow No. 5, also called Yellow 5 food dye or tartrazine. If you have an allergy to aspirin, you may be more likely to have a tartrazine allergy. Ask your pharmacist if you have questions about the ingredients in the famotidine product you are taking.

What should I tell my health care provider before using famotidine?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if famotidine is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your health care provider if you have any of the following.

  • Kidney problems
  • Heart problems or chest pain
  • Breathing problems
  • Other stomach problems, including nausea or vomiting or stomach pain
  • Heartburn that has lasted for more than three months
  • Heartburn with dizziness, lightheadedness, or sweating
  • Unexplained weight loss
  • Trouble or pain when swallowing food
  • Vomiting with blood
  • Bloody or black poop 

Other Medicines and Supplements. Famotidine may interact with other medicines and supplements. Before taking famotidine, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. It is not known if or how famotidine could affect pregnancy or harm an unborn baby. Tell your health care provider if you are pregnant or plan to become pregnant.

Breastfeeding. Famotidine passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed. Your health care provider will let you know if you should take famotidine while breastfeeding.

Interactions

Does famotidine interact with foods or drinks?

There are no known interactions between famotidine and foods or drinks.

It is unknown if drinking alcohol will affect famotidine. Alcohol may make certain stomach symptoms or conditions worse, so talk with your health care provider before drinking alcohol while taking this medicine.

Does famotidine interact with other medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking famotidine.

  • Tizanidine (Zanaflex), which is a muscle relaxant
  • Dasatinib (Phyrago, Sprycel), erlotinib, or nilotinib (Danziten, Tasigna), which are medicines used to treat certain types of cancer
  • A medicine for HIV, AIDS, or hepatitis C
  • Itraconazole (Sporanox, Tolsura) or ketoconazole, which is a medicine used for fungal infections
  • A proton pump inhibitor (PPI), such as esomeprazole (Nexium), lansoprazole (Prevacid), omeprazole (Prilosec), pantoprazole (Protonix), or rabeprazole (Aciphex)
  • Any other H2 blocker, such as cimetidine (Tagamet) or nizatidine (Axid) 

Famotidine may affect the absorption of some other medicines. Tell your health care provider about all medicines that you take or have recently taken.

This may not be a complete list of medicines that can interact with famotidine. Always check with your health care provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much famotidine?

If you or someone else has used too much famotidine, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of famotidine?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.

If you are using famotidine injection, it is usually given by a health care provider in a hospital or clinic. Your health care provider will make sure you are receiving famotidine as scheduled.