OverviewDosageSide EffectsInteractionsHalf-Life

Famotidine is currently the 115th most commonly prescribed drug in the United States. In 2017 alone, there were over 6,000,000 prescriptions. Considering how popular this drug is right now, it pays to know a little bit more about this medication, including how long famotidine stays in your system.

The FDA states the following information regarding famotidine half-life: 

Elimination half-life: 2.5 – 3.5 hours in adults

Oral bioavailability: 40 – 45%

Peak plasma levels: 1 – 3 hours


What is the half-life of famotidine?

Elimination half-life is 2.5 to 3.5 hours.

How long does famotidine stay in your system?

Considering the half-life of this drug is around 3.5 hours and that it takes roughly 5 half-lives to clear a drug from the body, famotidine may stay in your system for up to 17.5 hours. Of course, terminal phase half-lives may be longer, especially if you have severe kidney problems.

It is not common to test for antihistamines in routine drug screenings. However, some antihistamines are known to cause false-positive results for cannabis or even amphetamine screenings. Fortunately, famotidine is not reported to do so.

What is the best time to take famotidine?

It’s best to take famotidine once daily before bedtime or twice daily in the morning and before bedtime, with or without food.

What are the side effects of long term use of famotidine?

Serious side effects are rare, but some people may experience headache, constipation, or diarrhea. You should consult your doctor if any of these effects persist or worsen.

More serious side effects may include:

  • easy bruising/bleeding,
  • irregular heartbeat,
  • severe dizziness,
  • fainting,
  • seizure,
  • signs of infection, such as sore throat, fever and chills, and
  • mental/mood changes like restlessness, confusion, depression, and hallucinations.

If you experience any of these symptoms, consult with your doctor right away. 

How often can I take Pepcid?

Famotidine is usually taken once daily or twice daily. You can take famotidine for up to 6 weeks if you are treating symptomatic non-erosive GERD. For intestinal and stomach ulcers, you can take famotidine for up to 8 weeks. For treating erosive esophagitis (throat inflammation) diagnosed by endoscopy, you can take it for up to 12 weeks. For pathological hypersecretory conditions and reduction of the risk of ulcers recurrence, take famotidine as prescribed by your doctor.

Can you take Pepcid twice a day?

Yes. In certain instances, you can take famotidine twice daily.

Disclaimer: this article does not constitute or replace medical advice. If you have an emergency or a serious medical question, please contact a medical professional or call 911 immediately. To see our full medical disclaimer, visit our Terms of Use page.

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