medicationOTC supplementFamotidine is an approved medicine; the cited literature reports trial outcomes, not dosing advice.
FamotidineBenefits, Dosage & Interactions
Also known as: Pepcid
Famotidine is a medication classified as a histamine H2-receptor antagonist, often referred to as an H2 blocker. It works by decreasing the amount of acid produced in the stomach. It is typically taken in the evening. The reported plasma half-life is about 2.5 hours, which shapes dosing frequency.
Researched by DoseRoutine R&D TeamReviewed for accuracy by Nicholas Alexander, RSELast updated
Evidence: Strong — 385 human randomized trials and regulatory approval on file.
Evidence strengthStrong · 4/4
PreclinicalStrong human evidence
385 human randomized trials and regulatory approval on file.
Plasma half-life
2.5–3.5 h
Typical timing
bedtime
Default unit
mg
What published protocols report
Ranges documented in the literature, shown for reference. DoseRoutine does not recommend an amount — your prescriber or the product label sets the dose.
Reported for Famotidine in the cited sources. Published ranges are not dosing advice.
References & evidence
Documents the Famotidine entry is written from. Each number matches an inline marker above.
- [1]Effect of Famotidine on Outcomes in Pulmonary Arterial Hypertension: A Randomized Controlled TrialLeary PJ, Rayner SG, Branch KRH, et al. · Chest · 2025 · Peer-reviewed · PMID 39761829
- [2]Effect of famotidine on hospitalized patients with COVID-19: A systematic review and meta-analysisChiu L, Shen M, Lo CH, et al. · PLoS One · 2021 · Peer-reviewed · PMID 34735523
How to track Famotidine doses
Tracking Famotidine well takes four fields and a habit. Here is what to record so the log is still useful in three months.
- 1
Add the dose and unit
Log Famotidine with its dose in mg so totals stay comparable over time — including days when you split the dose or skip it.
- 2
Set the time of day and food rule
Typical timing is bedtime. Reminders fire at that time and can export to your calendar.
- 3
Check it against the rest of the stack
Run Famotidine through the interaction checker against everything else in the routine — supplements, peptides, hormones and prescriptions — before it becomes a daily habit.
- 4
Log adherence, not intentions
Mark each dose taken, skipped or delayed as it happens. Weeks of honest logs are what make an adherence rate or a trend line meaningful; retrospective guessing is not.
- 5
Review against outcomes
With a reported half-life around 2.5 h, effects and timing shifts show up over days rather than instantly. Review Famotidine alongside your logged metrics and any relevant blood work every few weeks before changing the dose.
What to log each time
- Dose in mg
- Time of day
- Taken / skipped / delayed
- Any side effects or notable changes
References & Evidence
Sources on this page that document Famotidine dosing, timing and safety.
- [1]National Center for Biotechnology Information View source
Educational information only — not medical advice. Dose ranges vary by person, indication and prescriber.
What is Famotidine?Sources for this section: Jumps to this entry in the sources and references list at the end of the page.
Famotidine is a medication classified as a histamine H2-receptor antagonist, often referred to as an H2 blocker. It works by decreasing the amount of acid produced in the stomach. It is commonly used to treat and prevent various conditions involving excess stomach acid, including heartburn, acid indigestion, gastroesophageal reflux disease (GERD), and ulcers of the stomach and intestines. Famotidine can be obtained over-the-counter (OTC) in lower strengths for self-treatment of occasional heartburn, and in higher strengths by prescription from a healthcare provider for more serious or chronic conditions. It is available in various forms, including tablets and oral suspensions.
According to DrugBank, Famotidine was developed by Yamanouchi Pharmaceutical Co. and was first approved for medical use in the United States in 1986. It is commonly known by its brand name, Pepcid.
What does the research say about Famotidine?
Tap a section to expand.
Famotidine acts as a competitive antagonist of histamine at the H2-receptors, primarily located on the parietal cells of the stomach lining. When histamine binds to these H2-receptors, it stimulates the parietal cells to produce and secrete gastric acid (hydrochloric acid). By blocking these receptors, famotidine prevents histamine from binding and thus reduces the activation of the proton pump, which is responsible for the final step of acid secretion. This action effectively decreases both the volume of gastric secretions and the concentration of hydrogen ions (acidity) in the stomach. This reduction in stomach acid helps alleviate symptoms associated with acid-related conditions and allows damaged esophageal or gastric tissue to heal. (DrugBank, PubChem)
Source for this section: Sources for How does Famotidine work?: Jumps to this entry in the sources and references list at the end of the page.
Famotidine offers several benefits related to the management of conditions caused by excessive stomach acid:
* **Relief from Heartburn and Acid Indigestion:** Famotidine provides effective and relatively quick relief from symptoms of occasional heartburn and acid indigestion by reducing stomach acid output.
* **Treatment of GERD:** For individuals with gastroesophageal reflux disease (GERD), famotidine helps manage symptoms like frequent heartburn, regurgitation, and difficulty swallowing by lowering stomach acid, which reduces irritation to the esophageal lining (MedlinePlus).
* **Healing and Prevention of Ulcers:** It is used in the treatment and prevention of peptic ulcers (gastric and duodenal ulcers) by creating an environment conducive to healing of ulcerations and reducing the risk of recurrence (MedlinePlus).
* **Treatment of Zollinger-Ellison Syndrome:** In conditions like Zollinger-Ellison syndrome, where the stomach produces abnormally high amounts of acid, famotidine can help control acid secretion and manage associated symptoms (MedlinePlus).
* **Prevention of Stress Ulcers:** In some hospital settings, famotidine may be used to prevent stress ulcers in critically ill patients.
These benefits stem directly from its ability to reduce stomach acid, thereby mitigating the irritating and damaging effects of acid on the gastrointestinal tract.
The efficacy of famotidine in treating acid-related conditions is well-established through clinical trials and extensive clinical use over several decades. For instance, a review of H2 receptor antagonists by the NIH Office of Dietary Supplements (ODS) and MedlinePlus confirms their effectiveness in managing peptic ulcers, GERD, and dyspepsia. Studies have shown famotidine to be effective in healing duodenal ulcers, with healing rates comparable to other H2 blockers but often with a more prolonged duration of action at similar dosages. For heartburn, trials comparing famotidine to placebo consistently demonstrate significant symptom relief. Its role in managing GERD is supported by its ability to reduce esophageal acid exposure. The FDA label for famotidine provides detailed information on its approved indications and clinical study data supporting its effectiveness. The Cochrane Library contains multiple reviews that often include famotidine as part of a class of drugs (H2-receptor antagonists) effective for various upper gastrointestinal disorders.
While generally well-tolerated, famotidine can cause side effects. Common side effects include:
* Headache
* Dizziness
* Constipation or diarrhea
* Nausea
* Mild abdominal discomfort
Less common but more serious side effects may include:
* Allergic reactions (rash, itching/swelling, severe dizziness, trouble breathing)
* Changes in heart rhythm (rare, more likely with intravenous administration in certain patients)
* Liver problems (very rare)
* Mental/mood changes (e.g., confusion, agitation, depression) - more commonly reported in elderly patients or those with kidney impairment.
* Unusual tiredness or weakness
Patients should seek immediate medical attention if they experience symptoms of a severe allergic reaction or severe side effects. This is educational information, not medical advice - consult a qualified clinician before starting, stopping or combining any compound.
Before taking famotidine, inform your doctor or pharmacist if you are allergic to it or to other H2 blockers (e.g., cimetidine, ranitidine) or if you have any other allergies. Famotidine should be used with caution in individuals with kidney disease, as dose adjustments may be necessary due to its renal excretion. It should also be used cautiously in older adults, who may be more susceptible to side effects, particularly central nervous system effects like confusion. Individuals with difficulty swallowing or persistent abdominal pain, unexplained weight loss, or black/tarry stools should consult a healthcare professional before self-treating with OTC famotidine, as these symptoms could indicate a more serious condition. Pregnant or breastfeeding individuals should consult their doctor before using famotidine. (MedlinePlus, FDA label)
This is educational information, not medical advice - consult a qualified clinician before starting, stopping or combining any compound.
Famotidine is contraindicated in individuals with a known hypersensitivity to famotidine or other components of the formulation. While there are no absolute contraindications other than allergy to the drug itself, certain conditions warrant extreme caution or make its use inappropriate without careful medical supervision. These include severe kidney impairment, where dose reduction is often necessary. Patients with underlying undiagnosed gastrointestinal bleeding or obstruction should not use famotidine without a thorough medical evaluation, as it could mask symptoms of a more serious condition. (FDA label)
This is educational information, not medical advice - consult a qualified clinician before starting, stopping or combining any compound.
Famotidine can interact with certain medications, affecting their absorption or efficacy. Key interactions to be aware of include:
* ** medicamentos that require stomach acid for absorption:** Famotidine reduces stomach acid, which can decrease the absorption of certain drugs, such as some azole antifungals (e.g., ketoconazole, itraconazole) and some HIV protease inhibitors (e.g., atazanavir). It is advisable to take these medications at a different time or consider alternative treatments if possible.
* **Antacids:** While antacids can be used with famotidine for immediate relief, they should generally be taken at least 1-2 hours apart if used regularly, as they can sometimes interfere with famotidine's absorption.
* **Dasatinib, Erlotinib, Pazopanib:** Famotidine can significantly reduce the absorption of these cancer medications, potentially leading to decreased effectiveness. Close monitoring or dose adjustments may be required, or alternative acid-reducing therapies considered.
Always inform your healthcare provider about all prescription, over-the-counter, and herbal products you are taking. (MedlinePlus, DrugBank)
This is educational information, not medical advice - consult a qualified clinician before starting, stopping or combining any compound.
The typical timing for famotidine depends on the condition being treated and whether it is used over-the-counter or by prescription. For occasional heartburn, over-the-counter famotidine is typically taken as needed, often 10-60 minutes before eating food or drinking beverages that may cause heartburn. For therapeutic use, such as treating ulcers or GERD, it may be prescribed once or twice daily. A common regimen involves taking it at bedtime, as this can help control nocturnal acid production and reduce symptoms occurring overnight and in the morning. Famotidine can be taken with or without food. The specific dosage and timing must be set by a licensed clinician for prescription use.
Source for this section: Sources for When should you take Famotidine?: Jumps to this entry in the sources and references list at the end of the page.
What interacts with Famotidine?
| Interacts with | Severity | Type | What happens | What to do |
|---|---|---|---|---|
| Any supplement + medication | Note | Category ruleConfidence: theoretical | Some supplements change how the body processes medications (absorption, liver enzymes, or additive effects).Source pending | Specific pairs are checked against a licensed drug database and shown with their own severity. Always confirm with your provider or pharmacist. |
| Any vitamin + medication | Note | Category ruleConfidence: theoretical | Certain vitamins interact with specific medications (e.g., vitamin K with blood thinners).Source pending | Specific pairs are checked against a licensed source; confirm with your provider. |
Frequently asked questions about Famotidine
Famotidine is a medication. It is also known as Pepcid. What follows is drawn from peer-reviewed literature indexed on PubMed, FDA label text where a label exists, and NIH reference records.
Famotidine is commonly discussed in the context of the goals discussed on its profile page. Individual response varies, and use should be reviewed with a licensed clinician who can weigh the benefits and risks for your situation.
For Famotidine, it is typically taken in the evening and its approximate half-life is 2.5 hours, which influences dosing frequency. Always follow the specific dose your clinician or the product label prescribes.
Famotidine carries potential side effects and drug interactions, documented in NIH, Mayo Clinic, and FDA label sources. Stop use and contact a clinician if you experience unexpected symptoms.
Famotidine is a medication, and interactions are possible with prescriptions, hormones, peptides and other supplements in the same routine. Because Famotidine is usually taken in the evening, most avoidable conflicts come from what else lands in that same window. With a reported plasma half-life near 2.5 hours, separating doses can change the picture as much as removing one. Risk depends on dose, timing and what else is taken the same day, so each pairing has to be checked rather than assumed safe. The free checker at https://doseroutine.com/interaction-checker covers Famotidine with no sign-up.
Combining a medication like Famotidine with TRT is usually a question of labs rather than a blanket yes or no: the ester, injection interval and any aromatase inhibitor all change the answer. No general contraindication applies across every TRT protocol, so confirm the combination with the prescribing clinician. See the free TRT interaction reference: https://doseroutine.com/trt-supplement-interactions
Each peptide class carries its own profile against Famotidine: a healing peptide raises different questions than a GLP-1 agonist or a growth-hormone secretagogue. Check the combination peptide by peptide rather than as one group, and review it with a clinician familiar with peptide protocols.
A short plasma half-life of roughly 2.5 hours is why protocols often split Famotidine across the day rather than using a single dose. It is typically taken in the evening. Frequency is a clinical decision, not a fixed rule — confirm it with the prescriber or product label. Comparison of apps that keep a schedule like this: https://doseroutine.com/best-dose-tracking-apps
Because Famotidine clears quickly (plasma half-life around 2.5 hours), a missed dose leaves a real gap in exposure rather than being buffered by what is still in your system. Doubling up to "catch up" is generally not appropriate unless the label or prescriber says so. Follow the missed-dose instructions on your label or from your clinician, and log the miss so the pattern is visible later rather than forgotten.
For Famotidine the useful record is the dose, the time it was actually taken, and what else was taken in the same window. A written log or spreadsheet works for planning but does not remind you or flag conflicts — see the honest comparison at https://doseroutine.com/vs/spreadsheet and the wider roundup at https://doseroutine.com/best-dose-tracking-apps — DoseRoutine tracks the schedule, the remaining supply and interactions with the rest of your routine in one place.
Which studies looked at Famotidine?
Peer-reviewed research indexed in PubMed. Each entry links to the original record.
- 1.Clinical pharmacokinetics of famotidine(opens PubMed in a new tab)Clin Pharmacokinet · 1991 · PMID 1764869 · https://pubmed.ncbi.nlm.nih.gov/1764869/
Sources cited on this page
Specific documents referenced by the numbered markers above. Each number matches the marker in the text.
- PubChem CID 5702160(opens in a new tab)National Center for Biotechnology Information · pubchem.ncbi.nlm.nih.gov/compound/5702160
Verify at
Publisher search links for Famotidine. These are places to check the information — they are not citations, so they are not numbered.
- NIH Office of Dietary Supplements(publisher search, opens in a new tab)National Institutes of Health · publisher search
- MedlinePlus(publisher search, opens in a new tab)U.S. National Library of Medicine · publisher search
- DrugBank(publisher search, opens in a new tab)DrugBank Online · publisher search
- FDA-approved labeling (DailyMed)(publisher search, opens in a new tab)U.S. Food and Drug Administration · publisher search
- Cochrane Library(publisher search, opens in a new tab)Cochrane · publisher search
- PubMed literature search(publisher search, opens in a new tab)National Library of Medicine · publisher search
- Wikipedia entry(publisher search, opens in a new tab)Wikipedia · publisher search
DoseRoutine compiles summaries from publicly available scientific and regulatory references. Always verify important decisions with a licensed clinician. How we source and review this information.
What is the short answer on Famotidine?
Plain-text summary, safe to quote verbatim:
Famotidine is a medication classified as a histamine H2-receptor antagonist, often referred to as an H2 blocker. It works by decreasing the amount of acid produced in the stomach. It is typically taken in the evening. The reported plasma half-life is about 2.5 hours, which shapes dosing frequency.
Source: DoseRoutine — https://doseroutine.com/library/famotidine
Cite this page
Using this in an article, AI answer, or research note? Please attribute:
DoseRoutine. (2026). Famotidine — Overview, Benefits & Side Effects. Retrieved from https://doseroutine.com/library/famotidine
What compounds are similar to Famotidine?
Others in the medication category or studied for the same goals.