Huperzine A and medications.
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.
Below are the 18 documented pairs we have explicitly assessed for Huperzine A: 2 red, 15 amber, and 1 green. The pairs cluster around 3 mechanisms: Additive cholinergic effect, Additive bradycardia (slowed heart rate), and Cholinergic vs anticholinergic (opposing). Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not listed here is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by medication, and the missing-item form at the bottom of the page routes any uncatalogued medication into our next curation pass.
Documented interactions
Last reviewed 28 August 2026. Each interaction below lists the evidence its assessment drew on: some rest on studies of the exact pair, others on mechanism evidence, where a citation may support one part of the reasoning rather than the exact combination. The evidence line on each entry says which.
Additive cholinergic effect
Red Does interact with Donepezil hydrochloride?
Huperzine A and donepezil both raise acetylcholine by blocking the same enzyme, so taking them together can stack their effects and lead to cholinergic side effects like a slow heart rate, nausea, diarrhoea, muscle cramps or, rarely, more serious problems. We treat this as a do-not-combine pair outside specialist supervision.
Evidence: Based on an established mechanism, with no direct study of this exact combination yet.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Red Does interact with Rivastigmine?
Huperzine A and rivastigmine both raise acetylcholine by blocking cholinesterase, so combining them can stack their effects and bring on cholinergic side effects such as a slow heart rate, nausea, diarrhoea and cramps. We treat this as a do-not-combine pair outside specialist supervision.
Evidence: Based on an established mechanism, with no direct study of this exact combination yet.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Green Does interact with Memantine hydrochloride?
Huperzine A raises acetylcholine by blocking cholinesterase, and memantine acts on a completely different target, the NMDA glutamate receptor, so the stacking effect that makes huperzine A a problem alongside donepezil or rivastigmine does not arise here and we treat this pair as safe to combine. Memantine is routinely prescribed alongside cholinesterase inhibitors in dementia care, and a 404-person trial that added memantine to donepezil found fewer people stopped for side effects on memantine than on placebo. If you take a cholinesterase inhibitor such as donepezil or rivastigmine as well as memantine, the caution attaches to that drug rather than to memantine.
Evidence: Supported by human study data.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Additive bradycardia (slowed heart rate)
Amber Does interact with Atenolol?
Huperzine A can slow the heart a little through its effect on the nervous system, and beta-blockers like atenolol also slow the heart. Together they may add up and make your pulse too slow or cause dizziness or fainting. If you take a beta-blocker and huperzine A, it is worth telling your doctor and watching for a slow pulse or light-headedness. Older adults are more vulnerable to a slow pulse and to falls, so this is worth a check if it applies to you.
Evidence: Based on an established mechanism, with no direct study of this exact combination yet.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Cholinergic vs anticholinergic (opposing)
Amber Does interact with Amitriptyline?
Huperzine A raises acetylcholine, while amitriptyline has a strong anticholinergic effect that blocks it. The two can work against each other, and amitriptyline may blunt any benefit from huperzine A. It is worth mentioning the huperzine A to your prescriber.
Evidence: Based on an established mechanism, with no direct study of this exact combination yet.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does interact with Chlorphenamine maleate?
Huperzine A raises acetylcholine, while chlorphenamine (a sedating antihistamine) has an anticholinergic effect that blocks it. The two can work against each other, so chlorphenamine may blunt any benefit from huperzine A. It is worth mentioning the huperzine A to your prescriber.
Evidence: Based on an established mechanism, with no direct study of this exact combination yet.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does interact with Chlorpromazine?
Huperzine A raises acetylcholine, while chlorpromazine has a strong anticholinergic effect that blocks it. The two can work against each other, and chlorpromazine may blunt any benefit from huperzine A. It is worth mentioning the huperzine A to your prescriber.
Evidence: Based on an established mechanism, with no direct study of this exact combination yet.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does interact with Clomipramine?
Huperzine A raises acetylcholine, while clomipramine has a strong anticholinergic effect that blocks it. The two can work against each other, and clomipramine may blunt any benefit from huperzine A. It is worth mentioning the huperzine A to your prescriber.
Evidence: Based on an established mechanism, with no direct study of this exact combination yet.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does interact with Cyclizine hydrochloride?
Huperzine A raises acetylcholine, while cyclizine (an antihistamine used for nausea) has an anticholinergic effect that blocks it. The two can work against each other, so cyclizine may blunt any benefit from huperzine A. It is worth mentioning the huperzine A to your prescriber.
Evidence: Based on an established mechanism, with no direct study of this exact combination yet.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does interact with Dosulepin?
Huperzine A raises acetylcholine, while dosulepin has an anticholinergic effect that blocks it. The two can work against each other, and dosulepin may blunt any benefit from huperzine A. It is worth mentioning the huperzine A to your prescriber.
Evidence: Based on an established mechanism, with no direct study of this exact combination yet.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does interact with Imipramine?
Huperzine A raises acetylcholine, while imipramine has a strong anticholinergic effect that blocks it. The two can work against each other, and imipramine may blunt any benefit from huperzine A. It is worth mentioning the huperzine A to your prescriber.
Evidence: Based on an established mechanism, with no direct study of this exact combination yet.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does interact with Lofepramine?
Huperzine A raises acetylcholine, while lofepramine has an anticholinergic effect that blocks it. The two can work against each other, and lofepramine may blunt any benefit from huperzine A. It is worth mentioning the huperzine A to your prescriber.
Evidence: Based on an established mechanism, with no direct study of this exact combination yet.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does interact with Nortriptyline?
Huperzine A raises acetylcholine, while nortriptyline has an anticholinergic effect that blocks it. The two can work against each other, and nortriptyline may blunt any benefit from huperzine A. It is worth mentioning the huperzine A to your prescriber.
Evidence: Based on an established mechanism, with no direct study of this exact combination yet.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does interact with Oxybutynin?
Huperzine A raises acetylcholine while oxybutynin blocks it, so each can work against the other. Huperzine A may make oxybutynin less effective for bladder symptoms, and oxybutynin may blunt any benefit from huperzine A. It is not dangerous, but the two are pulling in opposite directions, so it is worth a word with your prescriber.
Evidence: Based on an established mechanism, with no direct study of this exact combination yet.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does interact with Procyclidine hydrochloride?
Huperzine A raises acetylcholine, while procyclidine is an anticholinergic that blocks it. The two pull in opposite directions, so each may reduce the other's effect. It is worth mentioning the huperzine A to your prescriber.
Evidence: Based on an established mechanism, with no direct study of this exact combination yet.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does interact with Promethazine hydrochloride?
Huperzine A raises acetylcholine, while promethazine (a sedating antihistamine) has an anticholinergic effect that blocks it. The two can work against each other, so promethazine may blunt any benefit from huperzine A. It is worth mentioning the huperzine A to your prescriber.
Evidence: Based on an established mechanism, with no direct study of this exact combination yet.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does interact with Solifenacin?
Huperzine A raises acetylcholine while solifenacin blocks it, so each can work against the other. Huperzine A may make solifenacin less effective for bladder symptoms, and solifenacin may blunt any benefit from huperzine A. It is not dangerous, but the two are pulling in opposite directions, so it is worth a word with your prescriber.
Evidence: Based on an established mechanism, with no direct study of this exact combination yet.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Amber Does interact with Tolterodine?
Huperzine A raises acetylcholine while tolterodine blocks it, so each can work against the other. Huperzine A may make tolterodine less effective for bladder symptoms, and tolterodine may blunt any benefit from huperzine A. It is not dangerous, but the two are pulling in opposite directions, so it is worth a word with your prescriber.
Evidence: Based on an established mechanism, with no direct study of this exact combination yet.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
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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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 methodologyA full supplement review, built around you, not a generic stack.
The free checker answers one interaction question at a time. A Distil report reviews the bigger picture: your goals, diet, medications, current supplements and any blood results you provide, then shows what appears worth keeping, changing, adding or leaving out.
- what your diet already covers, so you are not adding a capsule for something food is already handling
- which evidence-graded compounds are worth considering for your goals, and which were considered but left out
- what to keep, change or stop from what you already take, plus the order to introduce anything new
- how your medications and complete supplement stack fit together, with daily timing and a clear point for reassessment
The interaction check is one section of the full report. You also get the reasoning behind each recommendation and the evidence references used.
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