Drug & supplement interaction

Alpha-gpc + Famotidine

Famotidine brand names: Pepcid, Famotidine, Pepcid AC, Famotidine Injection.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Alpha-gpc and Famotidine in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Alpha-gpc and Famotidine

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Famotidine and Alpha-gpc in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Alpha-gpc safety at a glance

Alpha-gpc overall Use caution Generally well tolerated in studies, but long-term safety is not fully established.
Pregnancy Avoid Not enough safety information; avoid unless directed by your doctor.
Breastfeeding Avoid Not enough safety information; avoid unless directed by your doctor.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Famotidine and Alpha-gpc? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Famotidine

Interactions in our licensed database are recorded against drug classes, not just single drug names. Famotidine is filed under 4 classifications — including h2-blockers, organic anion transporter 3 (oat3) substrates, seizure threshold lowering drugs. Alpha-gpc has documented interactions with 1 drug class — the most serious being scopolamine (transderm scop) (minor) — and none of Famotidine’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Alpha-gpc Does Interact With Other Medications

Alpha-gpc has 16 minor known drug interactions in our database — Famotidine isn’t one of them. If you take anything else, check it against the full list below.

Minor 16 No known interaction 2,814 (incl. Famotidine)
Taking anything else?

Check Another of Your Medications Against Alpha-gpc

Covers the 2,830 medications we’ve checked against Alpha-gpc. Pick one to open its full report.

What to actually watch for

No Interaction Found — But Data Suggests Alpha-gpc and Famotidine May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do. One of them is worth acting on rather than waiting out — marked below.

  • Confusion Worth acting on Additional detail

    Alpha-gpc

    “Orally, alpha-GPC has been rarely associated with dizziness, excitation, headache, and insomnia. Alpha-GPC use for at least 2 months has also been associated with an elevated risk of stroke when compared with non-users or those who used alpha-GPC for less than 2 months.

    Intramuscularly, alpha-GPC has been rarely associated with confusion, excitation, fainting, headache, and insomnia.”

    Alpha-gpc · Natural Medicines adverse-effect record, reported in cluster headache.

    2 sources cited
    1. 12102. Barbagallo Sangiorgi G, Barbagallo M, Giordano M, et al. Alpha-glycerophosphocholine in the mental recovery of cerebral ischemic attacks: An Italian multicenter clinical trial. Ann N Y Acad Sci 1994;717:253-69. PubMed
    2. 108883. Lee G, Choi S, Chang J, et al. Association of L-a glycerylphosphorylcholine with subsequent stroke risk after 10 Years. JAMA Netw Open 2021;4(11):e2136008.

    Famotidine

    Listed in the ADVERSE REACTIONS section of the FDA label for Famotidine. Read the label on DailyMed ›

  • Trouble sleeping / Dizziness / Headache Additional detail

    Alpha-gpc

    Recorded for Alpha-gpc in the same Natural Medicines adverse-effect record shown under Confusion above.

    Famotidine

    Listed in the ADVERSE REACTIONS section of the FDA label for Famotidine. Read the label on DailyMed ›

  • Diarrhea / Vomiting / Nausea Additional detail

    Alpha-gpc

    “Orally, alpha-GPC has been rarely associated with diarrhea, heartburn, nausea, and vomiting.

    Intramuscularly, alpha-GPC has been rarely associated with diarrhea, heartburn, nausea, and vomiting.”

    Alpha-gpc · Natural Medicines adverse-effect record, reported in diarrhea.

    1 source cited
    1. 12102. Barbagallo Sangiorgi G, Barbagallo M, Giordano M, et al. Alpha-glycerophosphocholine in the mental recovery of cerebral ischemic attacks: An Italian multicenter clinical trial. Ann N Y Acad Sci 1994;717:253-69. PubMed

    Famotidine

    Listed in the ADVERSE REACTIONS section of the FDA label for Famotidine. Read the label on DailyMed ›

  • A skin rash Additional detail

    Alpha-gpc

    “Orally, some patients can experience skin rash. Intramuscularly, alpha-GPC can cause erythema at the injection site.”

    Alpha-gpc · Natural Medicines adverse-effect record, reported in erythema.

    2 sources cited
    1. 12102. Barbagallo Sangiorgi G, Barbagallo M, Giordano M, et al. Alpha-glycerophosphocholine in the mental recovery of cerebral ischemic attacks: An Italian multicenter clinical trial. Ann N Y Acad Sci 1994;717:253-69. PubMed
    2. 12101. Di Perri R, Coppola G, Ambrosio LA, et al. A multicentre trial to the evaluate the efficacy and tolerability of alpha-glycerylphosphorylcholine versus cytosine diphosphocholine in patients with vascular dementia. J Int Med Res 1991;19:330-41.

    Famotidine

    Listed in the ADVERSE REACTIONS section of the FDA label for Famotidine. Read the label on DailyMed ›

Reported for Alpha-gpc but not commonly for Famotidine: heartburn and fainting.

Effects for Famotidine come from the ADVERSE REACTIONS section of its FDA label; effects for Alpha-gpc come from the Natural Medicines adverse-effect record, quoted above. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

From our Q&A

Questions About Alpha-gpc or Famotidine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Alpha-gpc or Famotidine, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Famotidine

This page covers Alpha-gpc only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Famotidine page lists 41 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), African Wild Potato (moderate), Banderol (moderate), Beer (moderate) and Biofeedback (moderate).

By severity: 1 major · 19 moderate · 21 minor.

From our pharmacist’s overview on the Famotidine page

“Famotidine (Pepcid) treats heartburn and acid reflux, a low-stakes job most days, but its interaction list earns genuine caution because one entry is rated major. That entry is activated charcoal, which can bind famotidine in the gut and sharply cut how much of the drug reaches your blood.”

Reviewed by 2 · Jul 18, 2026

Open the Famotidine interaction page

One more smart check

Taking Alpha-gpc as Part of a Dietary Supplement Product? Check It for Interactions

We hold 1,138 real supplement products containing Alpha-gpc, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Alpha-gpc. Even though Alpha-gpc itself has no known interaction with Famotidine, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Alpha-gpc and Famotidine Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Alpha-gpc
Top 10%

#144 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Famotidine
Top 25%

#588 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Alpha-gpc reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Alpha-gpc and Famotidine records this page draws on were last updated July 10, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Alpha-gpc

What is Alpha-gpc?

Alpha-gpc
  • Memory and learning support
  • Age-related cognitive decline
  • Alzheimer's disease and dementia (under study)
  • Athletic and physical performance
  • Source of choline

Alpha-GPC is a choline-containing compound used mainly for memory, brain health, and as a choline source. There is some evidence it may help cognition in people with dementia, but evidence in healthy people is limited. Talk to your pharmacist or doctor before starting it, especially if you take other medicines or have a health condition.

Synthesized compound; also found naturally in soy lecithin and small amounts in foods · Capsules, tablets, powder, liquid

An interaction check asks whether these two react with each other — it does not ask whether Alpha-gpc is a good idea for someone in your situation. Here is what our Alpha-gpc record says about it on its own.

Alpha-gpc: dosing

There is no official, standardized dose of Alpha-GPC for any condition. Doses used in research have varied depending on the purpose and the people studied.The safest approach is to follow the directions on the product label and not exceed them.

From our Alpha-gpc monograph — the full record covers uses, side effects and every documented interaction.

Read the full Alpha-gpc monograph & all interactions
Medication

About Famotidine

What Is Famotidine Used For?

Brand names: Pepcid, Famotidine, Pepcid AC, Famotidine Injection

Famotidine treats a range of acid-related conditions. Over-the-counter tablet products — including Acid Controller, Acid Reducer, Acid Relief, Amazon Basic Care Acid Reducer, basic care acid reducer, and Calmicid AC — are used to relieve and prevent heartburn associated with acid indigestion and sour stomach.

Prescription-strength famotidine tablets and oral suspension are indicated for active duodenal ulcers (ulcers in the small intestine), active gastric ulcers (stomach ulcers), GERD (acid reflux disease), erosive esophagitis (acid-damaged esophagus), and pathological hypersecretory conditions such as Zollinger-Ellison syndrome. The oral suspension is also indicated in children from birth onward for GERD and, in children one year and older, for peptic ulcer disease. Famotidine injection is used in hospitalized patients who cannot take medication by mouth.

See full Famotidine drug information
Keep checking

Other Drugs & Alpha-gpc

Browse every other medication we’ve checked against Alpha-gpc — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
0Moderate
16Minor
2,813No known interaction
16 Minor 2,813 No interaction
Minor

16 interactions

No interaction 2,813 drugs checked — show the list

We also checked Alpha-gpc against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,813 medications checked with no known interaction — see the full Alpha-gpc list.

See the full Alpha-gpc interactions page
See every supplement checked against Famotidine, ranked by severity
Evidence & sources

Alpha-gpc References

The 4 references that drive our Alpha-gpc monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Di Perri R, Coppola G, Ambrosio LA, et al. A multicentre trial to the evaluate the efficacy and tolerability of alpha-glycerylphosphorylcholine versus cytosine diphosphocholine in patients with vascular dementia. J Int Med Res 1991;19:330-41.
  2. Barbagallo Sangiorgi G, Barbagallo M, Giordano M, et al. Alpha-glycerophosphocholine in the mental recovery of cerebral ischemic attacks: An Italian multicenter clinical trial. Ann N Y Acad Sci 1994;717:253-69. PubMed
  3. Canal N, Franceschi M, Alberoni M, et al. Effect of L-alpha-glyceryl-phosphorylcholine on amnesia caused by scopolamine. Int J Clin Pharmacol Ther Toxicol 1991;29:103-7.
  4. Lee G, Choi S, Chang J, et al. Association of L-a glycerylphosphorylcholine with subsequent stroke risk after 10 Years. JAMA Netw Open 2021;4(11):e2136008.

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Alpha-gpc and Famotidine Together: Common Questions

Is it safe to take Alpha-gpc with Famotidine?
We do not list a known interaction between Alpha-gpc and Famotidine. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Do Alpha-gpc and Famotidine have any of the same side effects?
Yes — our sources link each of them separately to 8 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
How was the Alpha-gpc and Famotidine combination checked?
Interactions in our licensed database are recorded against drug classes. Famotidine is filed under 4 classifications, and Alpha-gpc has documented interactions with 1 drug class — none of Famotidine's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Alpha-gpc interact with any other medications?
Yes. Alpha-gpc has 16 documented drug interactions in our database — Famotidine is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Famotidine interact with any supplements?
Yes. Famotidine has documented interactions with 41 supplements in our database — Alpha-gpc is not one of them. The Famotidine interaction page linked on this page lists every one, ranked by severity.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Where next

Keep Exploring

Alpha-gpc monograph Uses, safety profile, and every drug interaction in one place Famotidine drug information The full plain-English guide to this medication Famotidine supplement interactions Every supplement checked against Famotidine, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 4 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Famotidine and Alpha-gpc?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.