Drug & supplement interaction

Huperzine A + Loperamide, Simethicone

Loperamide, Simethicone brand name: Imodium Advanced.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Huperzine A has a moderate interaction with Loperamide, Simethicone. Theoretically, huperzine A might decrease the effects of anticholinergic drugs.

Read the full interaction report
SeverityModerate
LikelihoodPossible
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Huperzine A and Loperamide, Simethicone

Here is the interaction we found between these two, with the evidence behind it.

Moderate

ANTICHOLINERGIC DRUGS

Why this applies to Loperamide, Simethicone

Loperamide, Simethicone falls under ANTICHOLINERGIC DRUGS — the group Huperzine A interacts with.

Theoretically, huperzine A might decrease the effects of anticholinergic drugs.
Huperzine A has acetylcholinesterase (AChE) inhibiting effects. In animal models, huperzine A reversed cognitive deficits induced by scopolamine, an anticholinergic drug.
Severity Moderate Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the basic idea. Huperzine A works by boosting a brain and gut chemical called acetylcholine. Loperamide (the anti-diarrhea part of Imodium Advanced) does the opposite in your gut: it calms down intestinal movement, partly through anticholinergic-type activity. So in theory, huperzine A could push back against loperamide and make it a little less effective at slowing things down. The simethicone (anti-gas) part isn't really involved here.

I want to be honest about how soft this is. This concern comes from animal and lab work, not from real people taking these two together, so the practical risk is likely small. Still, if you notice your loperamide isn't controlling diarrhea as well as usual, mention it to your pharmacist or doctor before changing anything.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Ye JW, Cai JX, Wang LM, Tang XC. Improving effects of huperzine A on spatial working memory in aged monkeys and young adult monkeys with experimental cognitive impairment. J Pharmacol Exp Ther 1999;288:814-9.. DOI
  2. Wang T, Tang XC. Reversal of scopolamine-induced deficits in radial maze performance by (-)-huperzine A: comparison with E2020 and tacrine. Eur J Pharmacol 1998;349:137-42. PubMed
  3. Cheng, D. H., Ren, H., and Tang, X. C. Huperzine A, a novel promising acetylcholinesterase inhibitor. Neuroreport 12-20-1996;8(1):97-101. PubMed

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Huperzine A Also Interacts With Other Medications

Huperzine A has 218 moderate known drug interactions in our database — the Loperamide, Simethicone one above is one of them. If you take anything else, check it against the full list below.

Moderate 218 No known interaction 2,612 (incl. Loperamide, Simethicone)
Taking anything else?

Check Another of Your Medications Against Huperzine A

Covers the 2,830 medications we’ve checked against Huperzine A. Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Loperamide, Simethicone

This page covers Huperzine A only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Loperamide, Simethicone page lists 82 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Henbane (major), Scopolia (major), St. John's Wort (major) and Angel's Trumpet (moderate).

By severity: 4 major · 59 moderate · 19 minor.

From our pharmacist’s overview on the Loperamide, Simethicone page

“Imodium Advanced combines loperamide, an anti-diarrheal opioid that normally stays out of the brain thanks to a transporter called P-glycoprotein, with simethicone for gas, and I treat its interaction list with more respect than most over-the-counter medicines warrant. Thirty-seven of the 82 interacting ingredients on file affect that…”

Reviewed by 2 · Jul 18, 2026

Open the Loperamide, Simethicone interaction page

One more smart check

Taking Huperzine A as Part of a Dietary Supplement Product? Check It for Interactions

We hold 86 real supplement products containing Huperzine A, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Huperzine A. Your product may carry other ingredients that interact with Loperamide, Simethicone too, on top of Huperzine A — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Huperzine A and Loperamide, Simethicone 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 Huperzine A
Top half

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

29 days ago today
Medication Loperamide, Simethicone
Top half

#732 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.

Supplement

About Huperzine A

What is Huperzine A?

Huperzine A
  • Memory and cognitive support
  • Alzheimer's disease and dementia
  • Age-related memory decline
  • Focus and mental performance
  • Myasthenia gravis (traditional/older use)

Huperzine A is a purified compound from a Chinese clubmoss that acts like a mild cholinesterase inhibitor, similar in mechanism to some prescription Alzheimer's drugs. Some small studies suggest it may modestly help memory in people with dementia, but the evidence is limited and the quality is uncertain. Because it is biologically active and not well standardized, talk with a pharmacist or doctor before using it, and avoid it during pregnancy and breastfeeding.

Read the full Huperzine A monograph & all interactions
Keep checking

Other Drugs & Huperzine A

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

0Major
218Moderate
0Minor
2,611No known interaction
218 Moderate 2,611 No interaction
Moderate

218 interactions

Showing 60 of 218 moderate interactions — see all 218 on the Huperzine A page.

No interaction 2,611 drugs checked — show the list

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

Showing the 60 most looked-up of 2,611 medications checked with no known interaction — see the full Huperzine A list.

See the full Huperzine A interactions page
See every supplement checked against Loperamide, Simethicone, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Huperzine A monograph › Uses, safety, and every drug interaction in one place Loperamide, Simethicone supplement interactions › Every supplement checked against Loperamide, Simethicone, 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 Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Huperzine A and Loperamide, Simethicone Together: Common Questions

Can you take Huperzine A with Loperamide, Simethicone?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Huperzine A and Loperamide, Simethicone interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

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

Still Have a Question About Loperamide, Simethicone and Huperzine A?

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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.