Supplement · Grade B

Huperzine A and medications.

Not yet catalogued in the Distil interactions database. We surface that distinction explicitly.

Huperzine A is in the Distil supplement database, evidence Grade B. The page below lists every medication we have explicitly assessed it against.

Huperzine A is an alkaloid isolated from Chinese club moss, and it acts more like a drug than a nutrient. It inhibits acetylcholinesterase, the enzyme that breaks down acetylcholine, so brain levels of that signalling chemical rise. The Grade B evidence is strongest for memory and cognition in age-related decline and Alzheimer's disease, much of it from Chinese RCTs; a 2008 Cochrane meta-analysis found benefits but rated the evidence quality as insufficient for firm recommendations. Because the mechanism is pharmacological, cycling is needed, typically two to four weeks on and two weeks off, and that limits its use as a daily long-term supplement. The interaction angle is genuine, not theoretical. Combining it with prescription cholinesterase inhibitors such as donepezil, rivastigmine, or galantamine risks additive toxicity and is a hard exclusion. It opposes anticholinergic drugs and its cholinergic effects on heart rate mean any cardiac medication warrants caution. Treat it as a short-course cognitive tool, not a casual everyday capsule.

We have not yet completed an explicit assessment of medications for Huperzine A in the Distil interactions database. We surface this distinction deliberately: the Distil checker tells you when we have explicitly assessed a pair and when we have not, because both are useful information. If you take Huperzine A alongside a medication, the checker below will surface anything already in our database, and the missing-item form at the bottom of the page routes uncatalogued pairs into our next curation pass.

What this list does not say. Pairs not flagged here are not implicitly safe. They are either not yet in our database, or fall outside our inclusion scope. Use the checker below to surface any medication, and submit a missing item if you take something we have not catalogued.

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For adults over 18. This tool gives evidence-graded information, not medical advice. Always discuss changes with your GP, especially if you take any medication, are pregnant, breastfeeding, or have a serious health condition.

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Your supplements

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How we decide

How we grade severity, choose what's in scope, and what we exclude.

Every call on this page is reasoned. We publish the full rubric for severity tiers, the medication inclusion logic, the evidence grades we accept, and what we deliberately leave out. About three thousand words. Worth reading once if you use this tool more than occasionally.

Read the full methodology

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If a supplement or medication you take isn't in our autocomplete, tell us. We go through what people flag every week and add what's missing.

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Distil's interactions database is reviewed and updated every quarter. We grade evidence transparently and publish our methodology, including every database change, at /about/methodology. This tool is information, not a substitute for clinical judgement. If you take medication and supplements together, your GP or pharmacist can review your full regimen against your medical history. If you want a full personalised stack reasoned against this same database, the Distil report is the next step up.