Herbs & Botanicals · Memory-supplement source plant

Clubmoss

Q: What is clubmoss?

The name covers two different plants. Chinese club moss (Huperzia serrata, qian ceng ta) is the source of huperzine A, which is sold as a memory supplement. Common clubmoss (Lycopodium clavatum) gives the yellow spore powder called lycopodium powder. Do not assume what is true for one is true for the other.

Q: What is huperzine A?

A natural compound from Chinese club moss that blocks the enzyme acetylcholinesterase, raising the brain messenger acetylcholine. It works in the same way as the Alzheimer's medicines donepezil, galantamine and rivastigmine. It is marketed in China as an Alzheimer's drug.

Q: Does huperzine A help Alzheimer's disease?

It is not proven. Cochrane (2008) found small trials with better scores but said most were low quality and the evidence was inadequate to recommend it. The best-designed US trial (210 people) did not show a benefit at the lower dose in its main test.

Q: What happened in the US trial?

A trial titled 'A phase II trial of huperzine A in mild to moderate Alzheimer disease' (Neurology, 2011) compared two dose levels with placebo for at least 16 weeks. The planned main test was negative. The higher dose improved one score at week 11 but not significantly by week 16. It was co-funded by the NIH and a company.

Q: Does it help mild memory problems or brain injury?

Cochrane found no trials in mild cognitive impairment, and a US phase II pilot after brain injury found no difference from placebo.

Q: What are the side effects?

As a cholinesterase blocker it can cause nausea, vomiting, diarrhoea, sweating, a slow heartbeat and muscle twitching. In short trials, side effects were reported as mild or absent, but the trials were small and low quality.

Q: Can I take it with donepezil or other Alzheimer's medicines?

Do not combine them without the prescriber's agreement. Both act on the same enzyme and effects could add up. We found no trial of the combination, so the size of the risk is unknown.

Q: Does it interact with heart or bladder medicines?

Possibly. Cholinesterase blockers can slow the heart, so beta blockers and similar drugs may add to that. Anticholinergic drugs (some bladder, allergy and sleep medicines) pull the other way and may cancel it out. These are class-based cautions; no huperzine A case reports were found.

Q: What about surgery?

Tell the surgeon and anaesthetist. Cholinesterase blockers can change how muscle-relaxing drugs work, and huperzine A stays in the body for many hours (half-life about 12 hours in healthy men).

Q: Is it safe in pregnancy or breastfeeding?

Avoid it. There are no human safety data, and a laboratory study of the club-moss family found alkaloid fractions harmful to fish embryos and nerve cells, with the strongest birth-defect signal from Huperzia serrata.

Huperzia serrata · also called Chinese club moss, qian ceng ta, huperzine A plant (common clubmoss, Lycopodium clavatum, is a different plant)

Chinese club moss is the plant that huperzine A comes from, a compound sold as a memory supplement. Huperzine A blocks the same enzyme as Alzheimer's drugs such as donepezil, so it can cause similar side effects and clash with medicines. Evidence is weak: Cochrane called it inadequate, and a US phase II trial missed its main goal. Do not use it to treat memory loss yourself; ask a doctor first, especially if you take heart or memory medicines, are pregnant or face surgery.

General information, not medical advice. Last substantive update October 25, 2026 · Not medically reviewed. A named clinician has not signed off on this page. How this page is made

About Clubmoss

Chinese club moss (Huperzia serrata) is a small spore-bearing plant used in traditional Chinese medicine, and the source of huperzine A, a compound that blocks acetylcholinesterase. That is how the Alzheimer's drugs donepezil, galantamine and rivastigmine work. Huperzine A is marketed as a drug in China and sold as a memory supplement elsewhere. Small, mostly Chinese trials report better memory scores, but Cochrane found the evidence inadequate, and a US phase II trial of 210 people missed its main goal. Like other drugs of its type it can cause nausea, sweating, a slow heartbeat and muscle twitching, and may clash with heart, bladder and Alzheimer's medicines. Supplements often do not contain what the label says. Ask a doctor or pharmacist about amounts.

What it is

Chinese club moss (Huperzia serrata, qian ceng ta) is a clubmoss, a spore-bearing plant, not a flowering one. The whole plant is the traditional Chinese medicine; huperzine A is the compound purified from it.

Common clubmoss (Lycopodium clavatum) is a different plant. Its fine yellow spores are called lycopodium powder and are used in homeopathy. It does not give huperzine A supplements, and the research on one cannot be applied to the other.

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What the research shows

In Alzheimer's disease, Cochrane (2008) pooled 6 small trials and found better scores on several memory and daily-living scales, with mild side effects, but said only one study was of adequate quality and there was inadequate evidence to recommend it. A 2013 review of 20 trials agreed on benefit but flagged poor methods.

The best-designed trial was the US 'phase II trial of huperzine A in mild to moderate Alzheimer disease' (210 people). Its main test failed. A higher dose looked better on one score at week 11 but not significantly at week 16. The study was co-funded by a company.

For mild cognitive impairment Cochrane found no trials. In vascular dementia the evidence is one tiny trial plus one small Chinese trial. After brain injury a US phase II pilot found no difference from placebo. A review of 12 Chinese trials in schizophrenia reported better memory scores as an add-on to antipsychotics; all were in China.

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At a glance

Traditional uses history, not proof

Traditional Chinese medicine: whole plant (qian ceng ta) for bruises, strains and swellings
Traditional Chinese medicine: schizophrenia, myasthenia gravis and organophosphate poisoning
Common clubmoss spores (lycopodium powder) used in European folk medicine and homeopathy

Studied for research

Alzheimer's disease symptoms: very low certainty (small, low-quality Chinese trials; US phase II main test negative)
Mild cognitive impairment and vascular dementia: insufficient
Thinking problems in schizophrenia, added to antipsychotics: low certainty (Chinese trials)
Cocaine use disorder and brain injury: insufficient

Main compounds

Huperzine A (blocks acetylcholinesterase)
Other Lycopodium alkaloids such as lycopodine

Common forms

Purified huperzine A tablets or capsules (used in trials and sold as supplements)
Whole plant (traditional Chinese medicine; not tested in trials we found)
Spore powder (lycopodium powder) and homeopathic Lycopodium from common clubmoss

Research links: Cochrane review: huperzine A for Alzheimer's disease (2008) · A phase II trial of huperzine A in mild to moderate Alzheimer disease (2011) · Analysis of 22 huperzine A supplements (2020) · Research Library · Genes & Biomarkers Library

The plant and its history

Accepted scientific name: Huperzia serrata (Thunb.) Trevis.
Naming authority: (Thunb.) Trevis.; accepted species in the GBIF backbone (key 2688470), checked by API 2026-10-25
Common names: Chinese club moss (English); Chinese clubmoss (English); Qian Ceng Ta (Chinese (pinyin; one review spells it 'Qiang Ceng Ta'))
Botanical family: Lycopodiaceae (clubmoss family; spore-bearing plants, not flowering plants). Not verified from a botanical flora.
Classification: Plantae > Tracheophyta > Lycopodiopsida > Lycopodiales > Lycopodiaceae > Huperzia > Huperzia serrata
Native range: Not verified here. The sources read describe it as a Chinese traditional medicine plant.
Habitat: Not verified from a primary source.
What the plant looks like: Roots: Not verified.; Stems: Not verified.; Leaves: Not verified.; Flowers: Clubmosses do not flower; they reproduce by spores.; Fruit: Not applicable.
Cultivation: Not verified. The 2007 review says it covers the natural resources of the source plants; we read only its abstract.
Harvest and processing: Not verified. The traditional medicinal part is the whole plant (Qian Ceng Ta).
Look-alikes and adulterants: Name: Lycopodium clavatum L. (common clubmoss); Note: A different genus in the same family (GBIF key 2688393; NCBI taxid 3252). Its spores are sold as lycopodium powder and used in homeopathy. Not the usual source of huperzine A supplements; evidence for one cannot be applied to the other.; Name: Other Huperzia and Phlegmariurus species; Note: Several species contain huperzine A according to the 2007 review; amounts and safety may differ.
Sustainability and conservation: Not verified. No IUCN assessment was retrieved.

Traditional use and history history, not clinical proof

Tradition or era	Documented use	Source
Traditional Chinese medicine	The whole plant Qian Ceng Ta (Huperzia serrata) was used for bruises, strains, swellings, schizophrenia, myasthenia gravis and organophosphate poisoning, according to a 2007 ethnopharmacology review.	p17644292
Modern drug development in China	Chinese scientists found that huperzine A blocks acetylcholinesterase. It is marketed in China for Alzheimer's disease, and a derivative (ZT-1) was developed.	p17644292
2000s US and Europe	A 2004 profile reported phase III trials in China, US/European marketing rights changing hands, and US trials in age-associated memory loss.	p14725492
Europe: common clubmoss	Lycopodium clavatum spores and whole herb are used traditionally and in homeopathy, according to our earlier summary of a 2014 review (not re-read, so NOT verified here).	summary-only: 2014 review of Lycopodium clavatum (not in the studies list)

Traditional use shows how a plant was used. It does not show that a supplement works or is safe today.

What is inside, and how it may work

What the plant contains and how those compounds act in cells and animals. Laboratory and animal mechanisms are not proven effects in people.

Main compounds

Compound	Family	Where it is concentrated	Activity studied	Level of evidence
Huperzine A PubChem 854026	Lycopodium alkaloid	Whole plant of Huperzia serrata (Qian Ceng Ta)	Reversible blocker of acetylcholinesterase that reaches the brain; reported neuroprotective effects in lab work. ^{9 8 15 11}	Laboratory research
Lycopodine PubChem 5462445	Lycopodium alkaloid	Associated with Lycopodium species; content in each plant NOT verified here	Not established. ¹²	Unknown
Other Lycopodium alkaloid fractions	alkaloids	Whole plants of Lycopodium clavatum and Huperzia serrata	Fractions were toxic to mouse nerve cells and zebrafish embryos in one lab study (summary-only). ²³	Animal research

Mechanisms, receptors and pathways

Target or pathway	Gene or receptor	What was found	Level
Acetylcholinesterase inhibition	ACHE	Huperzine A is a reversible blocker that reaches the brain, raising acetylcholine; this is the basis for its use in Alzheimer's disease and for class-based safety cautions. ^{8 15 9}	Laboratory research
Neuroprotection (lab)		Cochrane's background says it protected cells against peroxide, beta-amyloid, glutamate and ischemia in the lab. Not shown in people. ⁸	Laboratory research
CYP3A4 induction through the pregnane X receptor	CYP3A4, NR1I2 (PXR)	Huperzine A raised CYP3A4 gene activity and enzyme activity in human gut cells; may affect how other medicines are broken down. ²¹	Laboratory research

Absorption, metabolism and elimination

Absorption: Not described beyond the single-dose study in healthy Chinese men: the reference tablet reached about 1.55 ng/mL (peak).
Distribution: Described as blood-brain-barrier permeable (study abstract); no tissue data.
Metabolism: Not read. The CYP3A4 effect is on induction by huperzine A, not how it is cleared.
Elimination: Half-life about 12 hours in healthy men (12.09 +/- 1.90 hours; AUC 0 to 72 h 17.55 ng*h/mL).
Bioavailability: Two test formulations were bioequivalent to a reference formulation in fasting healthy men. Not studied in older adults, with food, or for supplement-shop products.

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Isolated compounds versus whole extracts

All human trials used purified huperzine A, not the whole plant or common clubmoss. The whole plant also contains other alkaloids, and one lab study found alkaloid fractions toxic. Do not assume huperzine A research applies to whole-plant products, to Lycopodium clavatum, or to supplement-shop products, which vary widely (2020 analysis).

Nutritional composition

A nutrient table does not apply: clubmoss is not a food and is used as a medicine or supplement only.

10benefits and uses looked at

23studies and sources checked

Low certaintybest evidence rating found

7lab markers tracked in trials

2 low certainty2 very low certainty6 not enough evidence

What is Clubmoss good for?

The main proposed uses and how strong the human evidence is for each. 'Low' means a small or single trial, 'very low' means weak, poor-quality or inconsistent trials, and 'insufficient' means too little to judge. Most research tested purified huperzine A, not the whole plant or common clubmoss, and not the supplements sold in shops.

Alzheimer's disease symptoms: Chinese trials and reviewsVery low certaintySmall, mostly Chinese trials of huperzine A tablets report better memory-test scores. Cochrane (2008) said the evidence was too weak to recommend it, because most trials were low quality. Alzheimer's disease: the US phase II trialLow certaintyA well-run US trial of 210 people found no benefit at the lower dose in its main test. A higher dose looked better on one early score, but not by week 16. Mild cognitive impairment (early memory problems)Not enough evidenceCochrane found no placebo-controlled trials, so nobody knows whether it helps here. Vascular dementiaNot enough evidenceCochrane found one tiny trial (14 people) with no clear effect. A later small Chinese trial reported better scores. Memory in school students who felt their memory was poorVery low certaintyOne four-week Chinese trial of 34 matched pairs reported a higher memory score. We found no repeat. Memory after moderate or severe brain injuryNot enough evidenceA US phase II pilot found no difference from placebo; both groups improved. Thinking problems in schizophrenia (added to antipsychotics)Low certaintyA review of 12 Chinese trials found better memory and symptom scores when added to antipsychotic medicine. All trials were in China. Cocaine use disorder (laboratory study)Not enough evidenceOne small lab study found it tolerated, with lower ratings of cocaine's effects at the lower dose. Not a treatment trial. Traditional uses of Qian Ceng Ta (bruises, myasthenia gravis, poisoning)Not enough evidenceTraditional use in China. We found no trials of the whole plant. Common clubmoss spores and homeopathic LycopodiumNot enough evidenceA different plant from huperzine A. No evidence of benefit found; inhaling the spores has caused lung harm.

Benefits, one by one

Each card is a research question, not a promise. Tap a goal to filter. Open a card to see the studies, doses and limits.

Alzheimer's disease symptoms: Chinese trials and reviews

Very low certainty

Small, mostly Chinese trials of huperzine A tablets report better scores on memory tests in Alzheimer's disease. Cochrane (2008) found the evidence too weak to recommend it, because most trials were of low quality.

4 studiesPurified huperzine A tablets or capsules in trials; the whole plant w…

Studies, doses and limits

What the trials found

Cochrane 2008 pooled 6 randomized trials (454 people): scores on MMSE, ADAS-Cog, CDR and daily-living scales were better than placebo, but the Hasegawa and Wechsler memory scales were not; side effects were mild and similar to placebo. A 2013 review of 20 trials (1,823 people) agreed on benefit for MMSE and daily living but called most trials high risk of bias, and noted that one trial found no change on ADAS-Cog. An early Chinese trial (103 people, 8 weeks) reported 58% improved on huperzine A against 36% on placebo. A 2009 pharmacist review judged the data limited by weak design.

Results

Statistically better test scores in small, low-quality trials. Cochrane concluded there was inadequate evidence to make any recommendation. The one large, well-run US trial (see next entry) did not confirm the main result.

Effect sizes as reported

Cochrane 2008: MMSE +2.81 points (95% CI 1.87 to 3.76); ADAS-Cog +1.91 at 6 weeks and +2.51 at 12 weeks; CDR -0.80; daily living -7.17 (95% CI -9.13 to -5.22).

Why this rating

Most trials were of poor quality (high risk of bias per both reviews), short (6 to 16 weeks), from China, and only one study was of adequate quality and size. The best-designed US trial was negative on its primary outcome. We did not find a GRADE rating, so this is our reading.

Form and dose studied

Purified huperzine A tablets or capsules in trials; the whole plant was not tested.

Who was studied

People with mild to moderate Alzheimer's disease, mostly in China.

Limits

Poor methods, short follow-up, publication bias is possible (not assessed in the abstracts), and no quality-of-life or carer outcomes.

Why researchers looked

Huperzine A was found in a Chinese traditional medicine plant and developed in China as a drug for Alzheimer's disease.

Traditional use

The whole plant (Qian Ceng Ta) was used in China for bruises, swellings and some nerve and mind conditions. Using purified huperzine A for memory is a modern development.

Proposed mechanism Pharmacological theory

Huperzine A blocks acetylcholinesterase, the enzyme that breaks down acetylcholine, a brain messenger involved in memory. Reviews describe it as a reversible blocker that reaches the brain; it is also said to protect nerve cells in lab work.

A proposed mechanism does not show that the effect happens in people.

Huperzine A acts like a cholinesterase-inhibitor medicine, so side effects such as nausea, sweating and a slow heartbeat, and clashes with other medicines, are possible. See the safety section. Not a do-it-yourself treatment for memory loss.

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Alzheimer's disease: the US phase II trial

Low certainty

A well-run US trial of 210 people did not find a memory benefit at the lower dose, the main test. A higher dose looked better on one early score but not by the end.

1 studiesTwo doses were tested; no dose advice is given here.

Studies, doses and limits

What the trials found

In 'A phase II trial of huperzine A in mild to moderate Alzheimer disease' (Neurology, 2011), 210 people were randomized to placebo or two doses of huperzine A for at least 16 weeks. The planned main analysis (lower dose, ADAS-Cog at week 16) showed no benefit. In secondary analyses the higher dose improved ADAS-Cog by 2.27 points at week 11 against a 0.29-point decline on placebo (p = 0.001), but at week 16 the difference was 1.92 against 0.34 points (p = 0.07). Global impression, behaviour and daily living were not significant at either dose. The authors rated it Class III evidence of no demonstrable cognitive effect at the lower dose.

Results

Failed its primary goal. Secondary hints of benefit at the higher dose were not confirmed at 16 weeks and were not a planned main test.

Effect sizes as reported

Higher dose, week 11: +2.27 vs -0.29 points (p = 0.001); week 16: +1.92 vs +0.34 points (p = 0.07). Lower dose: no change in ADAS-Cog.

Why this rating

One properly designed multicentre trial, null on its primary outcome. Rated low because it is a single trial, the secondary results are exploratory, and we read the abstract only. Funded by NIH/NIA and the company Neuro-Hitech.

Form and dose studied

Two doses were tested; no dose advice is given here.

Who was studied

210 US adults with mild to moderate Alzheimer's disease; 177 finished.

Limits

Single trial; adverse-event details were not read; industry co-funding.

Why researchers looked

To test whether huperzine A could compare with approved Alzheimer's drugs in a larger, rigorous, multicentre trial.

Traditional use

No traditional use applies; this is a modern drug trial.

Proposed mechanism Pharmacological theory

A proposed mechanism does not show that the effect happens in people.

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Mild cognitive impairment (early memory problems)

Not enough evidence

Cochrane looked for placebo-controlled trials in mild cognitive impairment and found none, so no one knows whether huperzine A helps here.

1 studiesNot applicable.

Studies, doses and limits

What the trials found

Cochrane review 'Huperzine A for mild cognitive impairment' (2012) found no eligible trials.

Results

No trial evidence either way.

Effect sizes as reported

No data.

Why this rating

The review was empty, so there is no basis for a rating beyond 'insufficient'.

Form and dose studied

Not applicable.

Who was studied

People with MCI.

Limits

A 2019 Chinese-language meta-analysis exists (PMID 30989926) but we did not read it.

Why researchers looked

Often asked because supplements are sold for early memory problems.

Traditional use

None.

Proposed mechanism Pharmacological theory

A proposed mechanism does not show that the effect happens in people.

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Vascular dementia

Not enough evidence

Cochrane found only one tiny trial (14 people) and no clear effect. A later Chinese trial of 78 people reported better scores, but it is a single small study.

2 studiesPurified huperzine A in trials.

Studies, doses and limits

What the trials found

Cochrane 2009: one trial (14 people), MMSE difference 2.40 points with a very wide confidence interval (-4.78 to 9.58), so benefit and harm both remained possible. Xu 2012: 78 people, vitamin C as the placebo, 12 weeks; the huperzine A group improved on MMSE, CDR and daily living and the placebo group did not, with no serious adverse events.

Results

Cochrane: no convincing evidence. One later small positive trial.

Effect sizes as reported

Cochrane MMSE WMD 2.40 (95% CI -4.78 to 9.58).

Why this rating

One tiny trial in the Cochrane review and one small single-centre trial afterwards; imprecise and not confirmed.

Form and dose studied

Purified huperzine A in trials.

Who was studied

Adults with mild to moderate vascular dementia, China.

Limits

Small, single-centre trials; abstracts compare groups with their own starting scores.

Why researchers looked

Vascular dementia (from reduced blood flow to the brain) has few treatments, so huperzine A was tried in China.

Traditional use

None.

Proposed mechanism Pharmacological theory

A proposed mechanism does not show that the effect happens in people.

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Memory in school students who felt their memory was poor

Very low certainty

One four-week Chinese trial of 34 matched pairs of school students who felt their memory was poor reported a higher memory score. It has not been repeated that we could find.

1 studiesCapsules of purified huperzine A.

Studies, doses and limits

What the trials found

Sun 1999: 34 pairs of junior middle school students, double-blind, 4 weeks. Memory quotient 115 +/- 6 with huperzine A against 104 +/- 9 with placebo (p < 0.01), and Chinese language scores also rose.

Results

Positive in one small trial only.

Effect sizes as reported

MQ 115 +/- 6 vs 104 +/- 9.

Why this rating

A single small, short trial from 1999 with no replication found; the students complained of memory problems, so they are not typical healthy adults.

Form and dose studied

Capsules of purified huperzine A.

Who was studied

68 school students, China.

Limits

Small, short, not replicated; no long-term safety in young people.

Why researchers looked

Tested because a cholinesterase blocker might help learning.

Traditional use

None.

Proposed mechanism Pharmacological theory

A proposed mechanism does not show that the effect happens in people.

No safety data in children or teenagers are established here; do not give it to young people.

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Memory after moderate or severe brain injury

Not enough evidence

A US phase II pilot found no difference from placebo. Everyone improved, which the authors link to a placebo effect.

1 studiesPurified huperzine A.

Studies, doses and limits

What the trials found

HUP-TBI (2020): randomized, double-blind, placebo-controlled phase II pilot, 12 weeks, memory on the CVLT-II. No difference between groups; both improved on memory and depression.

Results

Null result.

Effect sizes as reported

No between-group difference.

Why this rating

One pilot with a null result; too small to rule a small effect in or out.

Form and dose studied

Purified huperzine A.

Who was studied

Adults with moderate to severe TBI.

Limits

Pilot; sample size not recorded from the abstract.

Why researchers looked

Brain injury lowers acetylcholine, so a cholinesterase blocker was tried.

Traditional use

None.

Proposed mechanism Pharmacological theory

A proposed mechanism does not show that the effect happens in people.

²⁰

Thinking problems in schizophrenia (added to antipsychotic medicine)

Low certainty

A 2016 review of 12 Chinese trials found memory and symptom scores better when huperzine A was added to antipsychotic medicine. All trials were in China and quality is uncertain.

2 studiesPurified huperzine A as an add-on to antipsychotic medicine.

Studies, doses and limits

What the trials found

Zheng 2016 pooled 12 randomized trials (1,117 people, about 12 weeks on average) of huperzine A added to antipsychotics against placebo or antipsychotic alone. Huperzine A did better on memory quotient (WMD 10.59, 95% CI 5.65 to 15.53), IQ scales, card-sorting errors and total symptom scores (SMD -0.77, 95% CI -1.27 to -0.27). Drop-outs and adverse events were similar between groups.

Results

Better scores in pooled Chinese trials; the authors call for better-designed trials.

Effect sizes as reported

Memory quotient +10.59 (5.65 to 15.53); symptom score SMD -0.77 (-1.27 to -0.27); drop-outs RR 0.67 (0.36 to 1.24).

Why this rating

A meta-analysis of 12 trials, but all in China, risk of bias and certainty were not stated in the abstract, and trials were short. Our reading.

Form and dose studied

Purified huperzine A as an add-on to antipsychotic medicine.

Who was studied

Adults with schizophrenia spectrum disorders, China.

Limits

Short trials, one country, no GRADE seen, and combining with psychiatric medicine needs a doctor.

Why researchers looked

People with schizophrenia often have memory and thinking problems that antipsychotics do not fix.

Traditional use

Qian Ceng Ta has been used in China for schizophrenia, according to an ethnopharmacology review.

Proposed mechanism Pharmacological theory

Huperzine A blocks acetylcholinesterase, the enzyme that breaks down the brain messenger acetylcholine.

A proposed mechanism does not show that the effect happens in people.

Huperzine A acts like a cholinesterase-inhibitor medicine, so nausea, sweating, a slow heartbeat and medicine clashes are possible. See the safety section. Never add it to psychiatric medicine on your own.

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Cocaine use disorder (laboratory study)

Not enough evidence

One small laboratory study found huperzine A was tolerated and the lower dose reduced ratings of cocaine's effects. It is not a treatment trial.

1 studiesPurified huperzine A, short course.

Studies, doses and limits

What the trials found

De La Garza 2015: 14 to 17 people per group received placebo or huperzine A with intravenous cocaine on test days. Huperzine A did not change cocaine blood levels and was reported safe and well tolerated. The lower dose lowered ratings such as 'high'. The abstract's p-value text is garbled, so none is quoted.

Results

Preliminary and subjective; not a treatment outcome study.

Effect sizes as reported

Subjective ratings only.

Why this rating

One small controlled laboratory study with subjective ratings; no treatment trial.

Form and dose studied

Purified huperzine A, short course.

Who was studied

People who use cocaine, in a clinical laboratory.

Limits

Tiny; short; subjective ratings; unusual setting.

Why researchers looked

Cholinergic signalling is altered by drugs of abuse, so cholinesterase blockers were tried.

Traditional use

None.

Proposed mechanism Pharmacological theory

Huperzine A blocks acetylcholinesterase, the enzyme that breaks down the brain messenger acetylcholine.

A proposed mechanism does not show that the effect happens in people.

Huperzine A acts like a cholinesterase-inhibitor medicine, so nausea, sweating, a slow heartbeat and medicine clashes are possible. See the safety section.

Traditional uses of Qian Ceng Ta (bruises, myasthenia gravis, poisoning)

Not enough evidence

In Chinese medicine the whole plant was used for bruises, strains and swellings, and also for schizophrenia, myasthenia gravis and organophosphate poisoning. We found no trials of the whole plant for these uses.

1 studiesTraditional whole-plant use; the whole plant is not the same as a pur…

Studies, doses and limits

What the trials found

Ma 2007 lists these traditional uses and says huperzine A is marketed in China for Alzheimer's disease. We did not find clinical trials of the whole plant.

Results

Traditional use only; no human evidence read.

Effect sizes as reported

None.

Why this rating

Traditional use is not evidence of benefit.

Form and dose studied

Traditional whole-plant use; the whole plant is not the same as a purified huperzine A product.

Who was studied

Not applicable.

Limits

Only the abstract of a narrative review was read.

Why researchers looked

The plant's long use in China led to the discovery of huperzine A.

Traditional use

Whole Huperzia serrata plant (Qian Ceng Ta), per a 2007 ethnopharmacology review.

Proposed mechanism Pharmacological theory

No mechanism is claimed for the traditional uses.

A proposed mechanism does not show that the effect happens in people.

The whole plant contains huperzine A and other alkaloids; lab data hint at toxicity of alkaloid fractions (see safety).

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Common clubmoss (Lycopodium clavatum) spores and homeopathic Lycopodium

Not enough evidence

The yellow spore powder (lycopodium powder) and diluted homeopathic Lycopodium are a different material from huperzine A supplements. We found no human evidence of benefit. Inhaling the powder has caused lung harm in a case report.

1 studiesSpore powder, diluted homeopathic preparations, leaf extracts and tin…

Studies, doses and limits

What the trials found

Our existing summary found no systematic review of homeopathic Lycopodium trials; we did not run a full search for individual trials. The only human report we hold is a harm case (see safety).

Results

No evidence of benefit.

Effect sizes as reported

None.

Why this rating

No trials read.

Form and dose studied

Spore powder, diluted homeopathic preparations, leaf extracts and tinctures all exist; none are supported by trials we read.

Who was studied

Not applicable.

Limits

No trial search beyond our earlier summary.

Why researchers looked

Used traditionally in Europe, including homeopathy.

Traditional use

A 2014 review (from our existing summary) says the plant is used in Europe and Asia for many conditions but names no human studies.

Proposed mechanism Pharmacological theory

No mechanism claim is made for human benefit.

A proposed mechanism does not show that the effect happens in people.

Do not inhale the spores. Lycopodium (common clubmoss) is not huperzine A; its drug interactions have not been studied.

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Connections to the rest of health

How Clubmoss connects to the rest of our health knowledge graph. Every link says what kind of connection it is. A safety link (for example to the liver) is a warning, not a benefit. A study that merely mentions a topic never creates a benefit link.

Explore every connection: goals, body systems, organs, symptoms, genes

Kind of connection Connected to Search

A. Wellness goals

Connected to	Kind of connection	Evidence status	Context	Studies
Memory Support	Potential benefit	Very low certainty	Alzheimer's disease symptoms: Chinese trials and reviews: Small, mostly Chinese trials of huperzine A tablets report better scores on memory tests in Alzheimer's disease. Cochrane (2008) found the evidence too weak to recommend it, because most trials were of low quality. Mild cognitive impairment (early memory problems): Cochrane looked for placebo-controlled trials in mild cognitive impairment and found none, so no one knows whether huperzine A helps here.	^{8 18 16 4 19 7 17 14 20}
Cognitive Performance	Potential benefit	Very low certainty	Alzheimer's disease symptoms: Chinese trials and reviews: Small, mostly Chinese trials of huperzine A tablets report better scores on memory tests in Alzheimer's disease. Cochrane (2008) found the evidence too weak to recommend it, because most trials were of low quality. Vascular dementia: Cochrane found only one tiny trial (14 people) and no clear effect. A later Chinese trial of 78 people reported better scores, but it is a single small study.	^{8 18 16 4 7 17 22 9}
Brain Health	Potential benefit	Very low certainty	Alzheimer's disease symptoms: Chinese trials and reviews: Small, mostly Chinese trials of huperzine A tablets report better scores on memory tests in Alzheimer's disease. Cochrane (2008) found the evidence too weak to recommend it, because most trials were of low quality. Mild cognitive impairment (early memory problems): Cochrane looked for placebo-controlled trials in mild cognitive impairment and found none, so no one knows whether huperzine A helps here.	^{8 18 16 4 19 7 17 20 22 9 3}
Memory Support	Demonstrated clinical effect	Low certainty	Alzheimer's disease: the US phase II trial: A well-run US trial of 210 people did not find a memory benefit at the lower dose, the main test. A higher dose looked better on one early score but not by the end.	¹³
Cognitive Performance	Demonstrated clinical effect	Low certainty	Alzheimer's disease: the US phase II trial: A well-run US trial of 210 people did not find a memory benefit at the lower dose, the main test. A higher dose looked better on one early score but not by the end.	¹³
Mental Clarity	Potential benefit	Very low certainty	Memory in school students who felt their memory was poor: One four-week Chinese trial of 34 matched pairs of school students who felt their memory was poor reported a higher memory score. It has not been repeated that we could find.	¹⁴
Muscle Recovery	Traditional use	Not enough evidence	Traditional uses of Qian Ceng Ta (bruises, myasthenia gravis, poisoning): In Chinese medicine the whole plant was used for bruises, strains and swellings, and also for schizophrenia, myasthenia gravis and organophosphate poisoning. We found no trials of the whole plant for these uses.	⁹
Joint Support	Traditional use	Not enough evidence	Traditional uses of Qian Ceng Ta (bruises, myasthenia gravis, poisoning): In Chinese medicine the whole plant was used for bruises, strains and swellings, and also for schizophrenia, myasthenia gravis and organophosphate poisoning. We found no trials of the whole plant for these uses.	⁹
Immune Support	Traditional use	Not enough evidence	Common clubmoss (Lycopodium clavatum) spores and homeopathic Lycopodium: The yellow spore powder (lycopodium powder) and diluted homeopathic Lycopodium are a different material from huperzine A supplements. We found no human evidence of benefit. Inhaling the powder has caused lung harm in a case report.	¹⁰

B. Body systems

Connected to	Kind of connection	Evidence status	Context	Studies
Nervous System	Biological association	Very low certainty	Studied for: Alzheimer's disease symptoms: Chinese trials and reviews Studied for: Alzheimer's disease: the US phase II trial	^{8 18 16 4 13 19 7 17 14 20 22 9 3}
Musculoskeletal System	Biological association	Not enough evidence	Studied for: Traditional uses of Qian Ceng Ta (bruises, myasthenia gravis, poisoning)	⁹
Respiratory System	Biological association	Not enough evidence	Studied for: Common clubmoss (Lycopodium clavatum) spores and homeopathic Lycopodium	¹⁰

C. Body parts and organs

Connected to	Kind of connection	Evidence status	Context	Studies
Brain	Potential benefit	Very low certainty	Small trials and a Cochrane review give weak evidence for Alzheimer's symptoms; best US trial missed its main goal. Preparation or compound: Huperzine A (purified)	^{8 13 18}
Heart	Adverse effect or risk	Very low certainty	Slow heartbeat is an expected cholinesterase-blocker effect; not documented in huperzine A reports we found. Preparation or compound: Huperzine A	⁸
Gut	Adverse effect or risk	Very low certainty	Nausea, vomiting and diarrhoea are expected class effects; trials reported side effects as mild. Preparation or compound: Huperzine A	⁸
Lungs	Adverse effect or risk	Very low certainty	One case of granulomatous bronchiolitis after inhaling the spores. Preparation or compound: Lycopodium spore powder	¹⁰
Liver	Drug or supplement interaction	Very low certainty	Increased CYP3A4 (a liver and gut enzyme) activity in cell tests; clinical meaning unknown. Preparation or compound: Huperzine A	²¹

I. Biomarkers

Connected to	Kind of connection	Evidence status	Context	Studies
Mini-Mental State Examination (MMSE)	Biological association	Very low certainty	Measured in trials: raised. A lab change is not the same as a health benefit.	^{8 7}
Alzheimer's Disease Assessment Scale, cognitive part (ADAS-Cog)	Biological association	Low certainty	Measured in trials: mixed. A lab change is not the same as a health benefit.	^{8 13}
Activities of daily living (ADL) scales	Biological association	Very low certainty	Measured in trials: mixed. A lab change is not the same as a health benefit.	^{8 13}
Memory quotient (Wechsler Memory Scale)	Biological association	Very low certainty	Measured in trials: raised. A lab change is not the same as a health benefit.	¹⁴
Schizophrenia symptom scores (PANSS or BPRS)	Biological association	Low certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	²²
Memory quotient in schizophrenia (Wechsler Memory Scale-Revised)	Biological association	Low certainty	Measured in trials: raised. A lab change is not the same as a health benefit.	²²
Ratings of cocaine effects ('high', 'stimulated')	Biological association	Not enough evidence	Measured in trials: lowered. A lab change is not the same as a health benefit.	³

J. Genes, receptors and enzymes

Connected to	Kind of connection	Evidence status	Context	Studies
ACHE (acetylcholinesterase)	Preliminary mechanism	In vitro	Target of huperzine A.	^{8 9}
CYP3A4 and NR1I2 (pregnane X receptor)	Preliminary mechanism	In vitro	Induced by huperzine A in human gut cells.	²¹

K. Biological pathways

Connected to	Kind of connection	Evidence status	Context	Studies
Cholinergic (acetylcholine) signalling	Preliminary mechanism	Pharmacological theory	Increased by cholinesterase inhibition; basis for memory and side-effect effects.	⁸

L. Active compounds

Connected to	Kind of connection	Evidence status	Context	Studies
Huperzine A	Biological association	In vitro	Reversible blocker of acetylcholinesterase that reaches the brain; reported neuroprotective effects in lab work. Preparation or compound: Whole plant of Huperzia serrata (Qian Ceng Ta)	^{9 8 15 11}
Lycopodine	Biological association	Unknown	Not established. Preparation or compound: Associated with Lycopodium species; content in each plant NOT verified here	¹²
Other Lycopodium alkaloid fractions	Biological association	Animal	Fractions were toxic to mouse nerve cells and zebrafish embryos in one lab study (summary-only). Preparation or compound: Whole plants of Lycopodium clavatum and Huperzia serrata	²³

Each connection is stored with the ingredient, the connected record, the kind of connection, the evidence status, the supporting studies, the preparation or compound involved, and a review date (last reviewed October 25, 2026).

Evidence at a glance: what changed in 7 lab markers

Tap a number to show only those markers. Counts are markers, not people.

Other232

The evidence

The research centre for Clubmoss. Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.

Evidence by outcome

Alzheimer's disease symptoms: Chinese trials and reviews 4 studies · 103 people in trials Very low certainty Alzheimer's disease: the US phase II trial 1 studies · 210 people in trials Low certainty Mild cognitive impairment (early memory problems) 1 studies Not enough evidence Vascular dementia 2 studies · 78 people in trials Not enough evidence Memory in school students who felt their memory was poor 1 studies · 68 people in trials Very low certainty Memory after moderate or severe brain injury 1 studies Not enough evidence Thinking problems in schizophrenia (added to antipsychotic medicine) 2 studies Low certainty Cocaine use disorder (laboratory study) 1 studies Not enough evidence Traditional uses of Qian Ceng Ta (bruises, myasthenia gravis, poisoning) 1 studies Not enough evidence Common clubmoss (Lycopodium clavatum) spores and homeopathic Lycopodium 1 studies Not enough evidence

Bars show how many studies we found for each outcome, not how well it works. People are added up across trials only (reviews are not added, to avoid double counting).

How we rate evidence

High certainty

Several well-run trials or reviews agree; further research is unlikely to change the picture much.

Moderate certainty

Good trials point the same way, but some doubt remains.

Low certainty

Small, short or inconsistent trials. The finding could change with better research.

Very low certainty

Very little or very weak human data. Treat as a possibility only.

Mixed findings

Trials or reviews disagree with each other.

Not enough evidence

Not enough human research to say either way.

Evidence against

Good research found no benefit, or found harm.

We take the reviewers' own risk-of-bias and GRADE statements where they exist, and otherwise judge from study size, design, consistency, directness and whether a product matches what is sold. Many publications do not make evidence high. Method note: We started from the nutrient summary we hold, read PubMed abstracts, and checked GBIF, NCBI Taxonomy and PubChem. Full texts, LiverTox, LactMed, EMA and FDA records were not read. Certainty ratings are our own reading. No study is cited that we could not verify.

Study library: every study we checked 23

Design Research type Plant part Year from Search

Study	Design	People	Product, dose, length	Result
(no authors listed) 2004 Huperzine A Drugs R D · PMID 14725492 · DOI	Drug profile (other) other	Development status	Huperzine A (purified compound from Huperzia serrata, tablets or capsules) purified alkaloid	Reported huperzine A was in phase III trials in China for Alzheimer's disease; US and European marketing rights were being sold, and trials in elderly people with age-associated memory loss were under way in the US. Methods, limits and funding Outcomes: Development status Limitations: A 2004 industry-news style profile, not research. Funding and conflicts: Reports company interests (marketing rights). Read: abstract
Crawford 2020 The scoop on brain health dietary supplement products containing huperzine A Clin Toxicol (Phila) · PMID 31990212 · DOI	Product analysis (other) other	22 22 US dietary supplement products listing huperzine A	Huperzine A (purified compound from Huperzia serrata, tablets or capsules) supplement products	16 of 22 products (73%) had at least one labelled ingredient not detected. 16 (73%) contained compounds not on the label, including stimulants such as higenamine, hordenine, vinpocetine and others. Nine (41%) listed ingredients that do not meet the FDA's dietary supplement ingredient rules. Huperzine A ranged from below the limit of quantification up to 267.1 microgram per serving, and only two products were within 10% of the declared amount. 2 of 22 within 10% of the label Methods, limits and funding Outcomes: Whether label ingredients matched laboratory analysis Limitations: 22 products, US market, bought at one time. Many products also contained other claimed ingredients. Funding and conflicts: Not stated in the abstract. Read: abstract
De La Garza R 2nd 2015 Safety and Preliminary Efficacy of the Acetylcholinesterase Inhibitor Huperzine A as a Treatment for Cocaine Use Disorder Int J Neuropsychopharmacol · PMID 26364275 · DOI	Controlled trial	People who use cocaine, laboratory study (14 to 17 per group)	Huperzine A (purified compound from Huperzia serrata, tablets or capsules) purified alkaloid 0.4 mg or 0.8 mg (as reported) about 10 days · vs Placebo	Huperzine A was reported safe and well tolerated and did not change cocaine blood levels. The 0.4 mg group rated cocaine effects such as 'high' lower. The abstract's p-value text is garbled, so we quote no p-values. Methods, limits and funding Outcomes: Safety, cocaine blood levels, ratings of cocaine effects Limitations: Small laboratory study with intravenous cocaine; not a treatment trial; ratings are subjective. Funding and conflicts: PubMed record lists NIH extramural research support; no industry funding recorded from the abstract. Read: abstract
Desilets 2009 Role of huperzine a in the treatment of Alzheimer's disease Ann Pharmacother · PMID 19240260 · DOI	Narrative review	Clinical trials of huperzine A in Alzheimer's disease	Huperzine A (purified compound from Huperzia serrata, tablets or capsules) purified alkaloid 8 to 12 weeks in the trials reviewed	Preliminary data suggest that huperzine A may improve cognition; studies of 8 to 12 weeks found MMSE gains of 1 to 5 points. The review says the data are limited by weak study design and calls for large, randomized, placebo-controlled trials. Methods, limits and funding Outcomes: Cognition in Alzheimer's disease Limitations: Narrative review of weak studies, search to September 2008. Read: abstract
GBIF 2026 GBIF backbone: Huperzia serrata (Thunb.) Trevis. (key 2688470) GBIF species match API · Source	Database record plant	not applicable	Huperzia serrata whole plant	Accepted species, family Lycopodiaceae, order Lycopodiales (checked by API 2026-10-25). Methods, limits and funding Outcomes: Accepted name and family Limitations: Taxonomy database; synonyms not retrieved. Read: full-text
GBIF 2026 GBIF backbone: Lycopodium clavatum L. (key 2688393) GBIF species match API · Source	Database record plant	not applicable	Lycopodium clavatum spores / whole plant	Accepted species, family Lycopodiaceae (checked by API 2026-10-25). NCBI Taxonomy id 3252. Methods, limits and funding Outcomes: Accepted name and family Limitations: Taxonomy database only. Read: full-text
Hao 2009 Huperzine A for vascular dementia Cochrane Database Syst Rev · PMID 19370686 · DOI	Systematic review	14 Vascular dementia; one small trial included	Huperzine A (purified compound from Huperzia serrata, tablets or capsules) purified alkaloid · vs Placebo	Only one trial of 14 people was included. No significant difference in MMSE; the confidence interval was wide and included both clinically important benefit and clinically important harm. No deaths at the end of treatment. MMSE WMD 2.40 (-4.78 to 9.58) Methods, limits and funding Outcomes: MMSE, death, other outcomes Limitations: Search to July/August 2008. Authors found no convincing evidence of value; more research needed. Funding and conflicts: Conflict of interest: none known (Cochrane statement). Read: abstract
Li 2008 Huperzine A for Alzheimer's disease Cochrane Database Syst Rev · PMID 18425924 · DOI	Systematic review	454 People with Alzheimer's disease; 6 randomized trials	Huperzine A (purified compound from Huperzia serrata, tablets or capsules) purified alkaloid not recorded here 6 to 12 weeks (as reported in the review) · vs Placebo	Compared with placebo, huperzine A scored better on MMSE, ADAS-Cog, CDR, CIBIC-plus, ADAS-non-Cog and daily-living scales, but not on the Hasegawa Dementia Scale or the Wechsler Memory Scale. Side effects were mild and did not differ from placebo. Quality of life and carer burden were not reported. MMSE WMD 2.81; ADAS-Cog WMD 1.91 at 6 weeks and 2.51 at 12 weeks; ADL WMD -7.17 (MMSE 1.87 to 3.76; ADAS-Cog 12 weeks 1.74 to 3.28; ADL -9.13 to -5.22) Methods, limits and funding Outcomes: Memory and thinking scores (MMSE, ADAS-Cog, Hasegawa, Wechsler), global rating (CDR, CIBIC-plus), behaviour, daily living, side effects Limitations: Methodological quality of most trials was not high and only one study was of adequate quality and size. The authors concluded there was inadequate evidence to make any recommendation about its use. Search ended February 2006. Funding and conflicts: Conflict of interest: none known (Cochrane statement). Read: abstract
Ma 2007 Huperzine A from Huperzia species - an ethnopharmacolgical review J Ethnopharmacol · PMID 17644292 · DOI	Narrative review	Huperzia and Phlegmariurus species; chemistry, bioactivity, toxicology, trials, resources	Huperzine A (purified compound from Huperzia serrata, tablets or capsules) whole plant (Qian Ceng Ta) and purified alkaloid	Qian Ceng Ta (whole plant of Huperzia serrata) and relatives have been used in China for bruises, strains, swellings, schizophrenia, myasthenia gravis and organophosphate poisoning. Huperzine A was found by Chinese scientists to block acetylcholinesterase, is marketed in China as an Alzheimer's drug, and a derivative (ZT-1) was in development. Methods, limits and funding Outcomes: Traditional uses and discovery Limitations: Narrative review (2007); only the abstract was read. Read: abstract
Morresi-Hauf 2009 Granulomatous bronchiolitis due to aspiration of lycopodium spores by fire-breathing Pneumologie · PMID 18777466 · DOI	Case report	1 23-year-old man with cough, fever and lung infiltrates	Lycopodium spores (the fine powder, inhaled during fire-breathing) spores	Lung biopsy first looked like tuberculosis. Surgical biopsy showed aspiration bronchiolitis with granulomas and foreign particles; the cause (Lycopodium spores) was found only after repeated questioning. The authors describe it as the first such report. Methods, limits and funding Outcomes: Diagnosis Limitations: One case; frequency unknown. Article in German with English abstract. Read: abstract
NCBI PubChem 2026 PubChem: huperzine A (CID 854026) PubChem PUG REST · Source	Database record chemical	not applicable	Huperzine A isolated compound	CID 854026, formula C15H18N2O, molecular weight 242.32 (checked by API 2026-10-25). Methods, limits and funding Outcomes: Identity Limitations: Database record only. Read: full-text
NCBI PubChem 2026 PubChem: lycopodine (CID 5462445) PubChem PUG REST · Source	Database record chemical	not applicable	Lycopodine isolated compound	CID 5462445, formula C16H25NO, molecular weight 247.38 (checked by API 2026-10-25). Methods, limits and funding Outcomes: Identity Limitations: Database record only. Presence and amount in each plant not checked here. Read: full-text
Rafii 2011 A phase II trial of huperzine A in mild to moderate Alzheimer disease Neurology · PMID 21502597 · DOI	Controlled trial	210 Mild to moderate Alzheimer disease, US multicentre (Alzheimer's Disease Cooperative Study)	Huperzine A (purified compound from Huperzia serrata, tablets or capsules) purified alkaloid 200 microgram twice a day or 400 microgram twice a day at least 16 weeks · vs Placebo (n = 70 per arm)	The primary analysis failed: the lower dose did not change ADAS-Cog at 16 weeks. In secondary analyses the higher dose showed a 2.27-point ADAS-Cog improvement at week 11 against a 0.29-point decline on placebo (p = 0.001), but by week 16 the gap was 1.92 against 0.34 points (p = 0.07). Global change, behaviour and daily living were not significant at either dose. The authors classed it as Class III evidence of no demonstrable cognitive effect at the lower dose. Week 11 higher dose: +2.27 vs -0.29 (p = 0.001); week 16: 1.92 vs 0.34 (p = 0.07) Methods, limits and funding Outcomes: Primary: ADAS-Cog change at week 16 for the lower dose. Secondary: higher dose, MMSE, global change, daily living, behaviour Limitations: 177 of 210 finished the treatment phase. The higher dose was a secondary analysis. Full text not read; adverse events not recorded from the abstract. Funding and conflicts: Supported by NIH/NIA and Neuro-Hitech, Inc. (from the PMC front matter); the manuscript was shared with NIA representatives. Read: abstract
Sun 1999 Huperzine-A capsules enhance memory and learning performance in 34 pairs of matched adolescent students Zhongguo Yao Li Xue Bao (Acta Pharmacologica Sinica) · PMID 10678121	Controlled trial	68 Junior middle school students in China who complained of poor memory	Huperzine A (purified compound from Huperzia serrata, tablets or capsules) purified alkaloid two 50 microgram capsules twice a day (as reported) 4 weeks · vs Placebo capsules (starch and lactose)	Memory quotient was higher with huperzine A (115 +/- 6) than placebo (104 +/- 9, p < 0.01), and Chinese-language lesson scores also rose. MQ 115 +/- 6 vs 104 +/- 9 Methods, limits and funding Outcomes: Memory quotient and school language scores Limitations: Four weeks, 34 matched pairs, one Chinese hospital; no replication found. Not a healthy-adult supplement trial. Read: abstract
Wu 2017 Pharmacokinetics and tolerability of oral dosage forms of huperzine a in healthy Chinese male volunteers: a randomized, single dose, three-period, six-sequence crossover study J Huazhong Univ Sci Technol Med Sci · PMID 29058298 · DOI	Controlled trial	Healthy Chinese men, fasting	Huperzine A (purified compound from Huperzia serrata, tablets or capsules) purified alkaloid single dose (amount not recorded here) single dose, 72-hour sampling · vs Reference formulation of the same compound	Reference formulation: peak 1.550 ng/mL, half-life about 12 hours, AUC 17.55 ngh/mL. Two test formulations were bioequivalent to the reference and all three were well tolerated, with no adverse events reported. Half-life 12.09 +/- 1.90 hours Methods, limits and funding Outcomes:* Blood levels, tolerability, safety tests Limitations: Healthy men only, single dose, not older adults or people taking other medicines. Read: abstract
Xu 1995 Efficacy of tablet huperzine-A on memory, cognition, and behavior in Alzheimer's disease Zhongguo Yao Li Xue Bao (Acta Pharmacologica Sinica) · PMID 8701750	Controlled trial	103 Alzheimer's disease, Chinese multicentre	Huperzine A (purified compound from Huperzia serrata, tablets or capsules) purified alkaloid 0.2 mg twice a day (as reported) 8 weeks · vs Placebo tablets	About 58% (29 of 50) of the huperzine A group improved in memory, thinking and behaviour against 36% (19 of 53) on placebo (p < 0.05 between groups). No severe side effect was found. 58% vs 36% improved Methods, limits and funding Outcomes: Wechsler memory scale, Hasegawa, MMSE, daily living, side effects, vital signs and blood tests Limitations: Early Chinese trial, 8 weeks, abstract only; the definition of 'improved' and blinding details are not in the abstract. Read: abstract
Xu 2012 Treatment with Huperzine A improves cognition in vascular dementia patients Cell Biochem Biophys · PMID 21833673 · DOI	Controlled trial	78 Mild to moderate vascular dementia, China	Huperzine A (purified compound from Huperzia serrata, tablets or capsules) purified alkaloid 0.1 mg twice a day (as reported) 12 weeks · vs Vitamin C 100 mg twice a day as placebo	MMSE, CDR and ADL scores improved significantly in the huperzine A group (p < 0.01) and not in the placebo group. No serious adverse events were recorded. Within-group improvement; between-group numbers not given in the abstract Methods, limits and funding Outcomes: MMSE, CDR, daily living, adverse effects Limitations: Single-centre, 78 people, 12 weeks; abstract compares each group with its own baseline. Published after the Cochrane vascular dementia review. Read: abstract
Yang 2013 Huperzine A for Alzheimer's disease: a systematic review and meta-analysis of randomized clinical trials PLoS One · PMID 24086396 · DOI	Meta-analysis	1823 People with Alzheimer's disease; 20 randomized trials	Huperzine A (purified compound from Huperzia serrata, tablets or capsules) purified alkaloid not recorded here up to 16 weeks · vs Placebo, no treatment, psychotherapy or conventional medicine	Better MMSE at 8, 12 and 16 weeks, and better Hasegawa and Wechsler scores at 8 and 12 weeks; daily living favoured huperzine A. One trial found no change in ADAS-Cog or ADCS-ADL. No trial measured quality of life. No trial reported severe adverse events. Statistically significant benefit on several scales; no numbers recorded here from the abstract Methods, limits and funding Outcomes: MMSE, Hasegawa, Wechsler Memory Scale, daily living, CDR, ADAS-Cog, severe adverse events Limitations: Most trials had a high risk of bias; the authors say the findings must be read with caution. Search to June 2013. Funding and conflicts: No conflicts declared. Read: abstract
Yue 2012 Huperzine A for mild cognitive impairment Cochrane Database Syst Rev · PMID 23235666 · DOI	Systematic review	0 People with mild cognitive impairment (MCI)	Huperzine A (purified compound from Huperzia serrata, tablets or capsules) purified alkaloid · vs Placebo	No eligible trials were identified, so no meta-analysis was possible. The authors conclude the evidence is insufficient to judge huperzine A in MCI. Methods, limits and funding Outcomes: Cognition and safety in MCI Limitations: Search to May 2011. Empty review. Funding and conflicts: Conflict of interest: none (Cochrane statement). Read: abstract
Zafonte 2020 Huperzine A for the treatment of cognitive, mood, and functional deficits after moderate and severe TBI (HUP-TBI): results of a Phase II randomized controlled pilot study: implications for understanding the placebo effect Brain Inj · PMID 31638455 · DOI	Controlled trial	Moderate to severe traumatic brain injury	Huperzine A (purified compound from Huperzia serrata, tablets or capsules) purified alkaloid 12 weeks · vs Placebo	No difference in memory between huperzine A and placebo after 12 weeks. Both groups improved, including in depression, which the authors attribute to a placebo effect. No between-group difference Methods, limits and funding Outcomes: California Verbal Learning Test (memory), depression scores Limitations: Pilot trial; number of participants not in the abstract. Read: abstract
Zhang 2014 Induction of human CYP3A4 by huperzine A, ligustrazine and oridonin through pregnane X receptor-mediated pathways Pharmazie · PMID 25073399	Laboratory research in-vitro	Human gut-cell line (LS174T) and reporter assays	Huperzine A (pure compound) not applicable	Huperzine A raised CYP3A4 gene activity, protein and enzyme activity through the pregnane X receptor in cells. The authors say this might contribute to drug-drug interactions. Methods, limits and funding Outcomes: CYP3A4 and PXR activity Limitations: Cell work only; no human interaction has been shown from this. Read: abstract
Zheng 2016 Adjunctive huperzine A for cognitive deficits in schizophrenia: a systematic review and meta-analysis Hum Psychopharmacol · PMID 27302211 · DOI	Meta-analysis	1117 Schizophrenia spectrum disorders; 12 randomized trials, all in China	Huperzine A added to antipsychotic medicine purified alkaloid 11.7 +/- 6.0 weeks on average · vs Placebo or antipsychotic alone	Huperzine A add-on outperformed comparators on memory quotient, IQ scales, card-sorting errors and total symptom scores. Drop-outs and adverse events were similar between groups. Memory quotient WMD 10.59; symptom scores SMD -0.77; discontinuation RR 0.67 (Memory quotient 5.65 to 15.53; symptoms -1.27 to -0.27; discontinuation 0.36 to 1.24) Methods, limits and funding Outcomes: Wechsler memory and intelligence scales, Wisconsin Card Sorting Test, PANSS/BPRS, drop-outs, adverse events Limitations: All trials were from China; risk of bias and certainty grade not stated in the abstract; the authors call for better-designed trials. Read: abstract
not recorded (summary only) 2021 Toxicity Evaluation of Lycopodiaceae Extracts on Mouse Neuronal Cells and Zebrafish Embryos VNU Journal of Science: Natural Sciences and Technology · Source	In vitro and animal in-vitro	Mouse nerve cells and zebrafish embryos	Alkaloid fractions from Lycopodium clavatum and Huperzia serrata whole plant fractions	Per our existing summary: an alkaloid fraction was toxic to mouse nerve cells and zebrafish embryos (heart-sac swelling, tail defects); the strongest birth-defect signal was from Huperzia serrata. The authors suggest caution at high concentrations and in pregnancy. Methods, limits and funding Outcomes: Toxicity to cells and embryos Limitations: Lab and fish-embryo work only. We have not re-opened this paper; its details come from our earlier summary. Read: summary-only

What we do not know yet

What the evidence supports: weak, low-quality trials of purified huperzine A; the best US trial was negative on its main test.
What is uncertain: whether any benefit is large enough to matter, how long it lasts, and how often side effects and drug interactions occur.
What is missing: large long-term trials, any trial in mild cognitive impairment, whole-plant trials, case-report data on interactions, and independent testing of supplements.

How new research is added

New studies are found by a saved PubMed search and queued for a person to read before any rating or safety wording changes.

Lab markers

What changed in blood or saliva tests during trials. A changed number is not the same as feeling or being healthier, and we give no "normal ranges".

Other 7

▲

Mini-Mental State Examination (MMSE)

Raised in trials

A 30-point quick test of memory, orientation and thinking. Higher is better.

Very low certainty

Results and what it means

Why it was measured

A common way to track thinking in dementia trials.

Statistical vs. clinical meaning

Statistically significant in pooled low-quality trials; a few points on this test may not be noticeable day to day, and the Cochrane authors still advised against a recommendation.

Safety implication

None from the measure itself.

Study	Result	People	Product
⁸	Huperzine A better than placebo: mean difference 2.81 points (95% CI 1.87 to 3.76)	Alzheimer's disease, 6 trials	Huperzine A tablets, 6 to 12 weeks
⁷	Mean difference 2.40 points (95% CI -4.78 to 9.58), not significant	Vascular dementia, 1 trial of 14	Huperzine A

^{8 7}

↕

Alzheimer's Disease Assessment Scale, cognitive part (ADAS-Cog)

Mixed results in trials

A test of memory, language and thinking used in Alzheimer's drug trials. Higher scores mean worse performance, so a drop is an improvement.

Low certainty

Results and what it means

Why it was measured

The standard cognitive measure in Alzheimer's drug trials.

Statistical vs. clinical meaning

The pooled Chinese trials suggest a small gain; the larger US trial failed its main test. Treat as unproven.

Safety implication

None from the measure itself.

Study	Result	People	Product
⁸	Cochrane pooled improvement of 1.91 points at 6 weeks and 2.51 at 12 weeks (95% CI 1.27 to 2.55 and 1.74 to 3.28)	Alzheimer's disease, small trials	Huperzine A
¹³	Lower dose: no change at week 16 (the main test). Higher dose: 2.27-point improvement at week 11 vs 0.29-point decline on placebo (p = 0.001); 1.92 vs 0.34 at week 16 (p = 0.07)	210 US adults with mild to moderate Alzheimer's	Two dose levels, at least 16 weeks

^{8 13}

↕

Activities of daily living (ADL) scales

Mixed results in trials

Scores for how well a person manages washing, dressing, eating and similar tasks.

Very low certainty

Results and what it means

Why it was measured

A practical measure of day-to-day function.

Statistical vs. clinical meaning

The pooled result comes from low-quality trials; the large US trial found no change.

Safety implication

None from the measure itself.

Study	Result	People	Product
⁸	Pooled ADL mean difference -7.17 (95% CI -9.13 to -5.22) in favour of huperzine A	Alzheimer's disease, small trials	Huperzine A
¹³	Daily living not significantly changed at either dose	210 US adults	Two dose levels

^{8 13}

▲

Memory quotient (Wechsler Memory Scale)

Raised in trials

A memory test score scaled like an IQ; higher is better.

Very low certainty

Results and what it means

Why it was measured

Used to track memory change in the teen trial.

Statistical vs. clinical meaning

One small trial; not replicated.

Safety implication

None from the measure itself.

Study	Result	People	Product
¹⁴	115 +/- 6 with huperzine A vs 104 +/- 9 with placebo (p < 0.01)	34 pairs of school students, China	Huperzine A capsules, 4 weeks

¹⁴

▼

Schizophrenia symptom scores (PANSS or BPRS)

Lowered in trials

Clinician-rated scales of psychosis symptoms; lower scores mean fewer symptoms.

Low certainty

Results and what it means

Why it was measured

The usual way to track symptoms in schizophrenia trials.

Statistical vs. clinical meaning

Statistically significant across pooled Chinese trials; certainty not graded in the abstract.

Safety implication

Adverse events were similar to comparators in the review.

Study	Result	People	Product
²²	Total score lower with huperzine A: SMD -0.77 (95% CI -1.27 to -0.27), 8 trials	Schizophrenia spectrum disorders	Huperzine A added to antipsychotic medicine

²²

▲

Memory quotient in schizophrenia (Wechsler Memory Scale-Revised)

Raised in trials

A memory score; higher is better.

Low certainty

Results and what it means

Why it was measured

Memory is a main target when treating thinking problems in schizophrenia.

Statistical vs. clinical meaning

Large on the test scale, but from short Chinese trials; real-life benefit unknown.

Safety implication

None identified from this measure.

Study	Result	People	Product
²²	Weighted mean difference 10.59 points (95% CI 5.65 to 15.53)	Schizophrenia spectrum disorders	Huperzine A added to antipsychotics

²²

▼

Ratings of cocaine effects ('high', 'stimulated')

Lowered in trials

Volunteers rate how strong a cocaine dose feels.

Not enough evidence

Results and what it means

Why it was measured

A lab marker of how rewarding a drug feels.

Statistical vs. clinical meaning

Subjective ratings in a lab; not a measure of staying off cocaine.

Safety implication

Reported safe in this small study.

Study	Result	People	Product
³	Lower-dose group rated cocaine's effects lower than placebo; no change in cocaine blood levels	14 to 17 people per group	Huperzine A before intravenous cocaine

Safety

What studies and official sources say about side effects, medicines and who should check first. Each point shows what kind of evidence it comes from.

Main points to know 9

Huperzine A works like a cholinesterase-inhibitor medicine, so it can cause the same kind of side effects. It blocks the enzyme that breaks down acetylcholine, as donepezil, galantamine and rivastigmine do. The effects expected from that action are nausea, vomiting, diarrhoea, stomach cramps, sweating, extra saliva, a slow heartbeat and muscle twitching or cramps. Trials of purified huperzine A in older adults and healthy volunteers reported mild or no side effects (Cochrane 2008: mild and not different from placebo; healthy volunteers: no adverse events with a single dose), but trials are short and small. We did not read the adverse-event tables of the US phase II trial, so we cannot state how often each effect happened. Pharmacological theory ^{8 18 15 13}
Do not combine it with Alzheimer's medicines of the same type, unless a doctor says so. Donepezil, galantamine and rivastigmine also block acetylcholinesterase. Taking two blockers together could add up, raising the risk of a slow heartbeat, vomiting, fainting and other cholinergic effects. This is a drug-class concern. We found no published case report or trial of the combination, so the size of the risk is unknown. Pharmacological theory ⁸
Medicines that slow the heart, and medicines that block acetylcholine, may clash with it. Cholinesterase blockers can slow the heart, so beta blockers, digoxin and some calcium-channel blockers could add to that (theory). Anticholinergic medicines (some bladder, allergy, sleep and antidepressant drugs) work in the opposite direction and may cancel each other. No human report was found for huperzine A; these are class-based cautions. Pharmacological theory ⁸
Tell your surgeon and anaesthetist. Cholinesterase blockers can change how muscle-relaxing anaesthetic drugs behave. We found no huperzine A report on this and no agreed time to stop it before surgery; ask the surgical team early. Huperzine A has a half-life of about 12 hours in healthy men, so its effects may last well beyond a day. Pharmacological theory ¹⁵
Pregnancy and breastfeeding: avoid. There are no human safety data. A laboratory study in zebrafish embryos and nerve cells (read only in summary) found alkaloid fractions from the club-moss family harmful, with the strongest birth-defect signal from Huperzia serrata. That is not proof for people, but it is a reason to avoid it. Laboratory research ²³
What is on the label may not be in the bottle. A 2020 analysis of 22 US huperzine A supplements found that only two had the labelled amount within 10%, 73% had a labelled ingredient not detected, and 73% contained unlabelled compounds including stimulants. Dose-related side effects are hard to predict if the amount is unknown. Other ²
Do not use it to treat memory loss or dementia on your own. Memory loss has many causes, some treatable. Huperzine A has not been shown to work reliably: Cochrane called the evidence inadequate, and the best US trial missed its main goal. See a doctor for a proper check first. Systematic review ^{8 13 19}
The spore powder (lycopodium powder) should not be inhaled. A man developed granulomatous lung inflammation after inhaling Lycopodium spores while fire-breathing. It was found only after the cause was asked about repeatedly. One case; frequency unknown. Case report ¹⁰
Chinese club moss and common clubmoss are different plants. Huperzine A comes from Huperzia serrata. Common clubmoss (Lycopodium clavatum) is another plant whose spores are sold as lycopodium powder. Do not assume the cautions or the evidence for one apply to the other. Other ^{5 6}

Side effects 7

Effect	How often	Severity and recovery	Evidence
Nausea, vomiting, diarrhoea, stomach cramps Expected from cholinesterase blockers. Cochrane 2008 said adverse events with huperzine A were mild and not different from placebo; no frequencies given in the abstract.	Not established	mild to moderate Expected to fade when the exposure stops (class effect).	Pharmacological theory ⁸
Sweating, extra saliva, blurred vision Class effects of cholinesterase blockers; not counted in the abstracts we read.	Not established	mild Expected to fade when the exposure stops.	Pharmacological theory ⁸
Slow heartbeat, dizziness or fainting Class effect; we found no huperzine A case report in PubMed searches. A slow pulse is also why heart-rate-lowering medicines matter.	Not established	potentially serious Usually reversible once the exposure ends, but can cause falls.	Pharmacological theory ⁸
Muscle twitching, cramps, weakness Excess acetylcholine at the muscles; severe weakness would be an emergency.	Not established	mild to serious Expected to ease when the blocker wears off.	Pharmacological theory ⁸
Few or no side effects in short trials 20-trial review: no severe adverse events reported; schizophrenia add-on review: adverse events and drop-outs similar to comparators; healthy men: none after a single dose. Trials were short and poor quality, so rare harms may be missed.	Not established	not applicable Not applicable	Meta-analysis ^{18 22 15}
Lung inflammation after inhaling the spore powder One fire-breather; not related to taking supplements.	Not established	serious Not described in the abstract.	Case report ¹⁰
Unlisted stimulants or other ingredients in supplements Includes stimulants and a substance on the FDA advisory list.	16 of 22 products analysed contained unlabelled compounds	varies Not applicable	Other ²

Liver

We found no published human case of liver injury from huperzine A or from clubmoss in our PubMed searches (limited, not exhaustive). The Chinese trial of tablets that measured liver blood tests (ALT) among its safety checks reported no severe side effect, but the abstract gives no liver numbers. An NIH LiverTox entry was not found or opened, so we cannot quote its likelihood score. Not finding reports is not proof of safety. ¹⁶

How often. No frequency available.

Monitoring. No agency monitoring advice found. People with liver disease should ask their doctor first, because the effect of liver disease on huperzine A levels has not been studied.

This is a safety connection. It is not evidence that Clubmoss supports liver health.

Medicines and supplements 8

With	Why it matters	Importance	Evidence	What to do
Donepezil, galantamine, rivastigmine (Alzheimer's cholinesterase inhibitors) prescription	Both act on the same enzyme; effects could add up.	No human report of the combination was found; the risk is theoretical but plausible.	Pharmacological theory Very low certainty ⁸	Do not combine unless the prescribing doctor knows and agrees.
Other cholinergic drugs (for example bethanechol, pilocarpine) and nerve agents or pesticides that block cholinesterase prescription	More acetylcholine activity could add up with huperzine A.	Not studied.	Pharmacological theory Very low certainty ⁹	Tell the prescriber; avoid working with organophosphate pesticides while taking it without advice.
Anticholinergic medicines (some bladder, allergy, sleep, antidepressant and Parkinson's drugs) prescription or over-the-counter	They block the messenger that huperzine A is meant to increase; the two may cancel out.	Not studied for huperzine A.	Pharmacological theory Very low certainty ⁸	Ask a pharmacist; one of the two may not work as intended.
Beta blockers, digoxin and other heart-rate-lowering medicines prescription	Both can slow the heart; the combination might cause a very slow pulse.	No case report found for huperzine A.	Pharmacological theory Very low certainty ⁸	Ask the prescriber before combining; report dizziness or fainting.
Anaesthetic muscle relaxants (surgery) procedure	Cholinesterase blockers can change how these drugs act.	No huperzine A report found.	Pharmacological theory Very low certainty ¹⁵	Tell the surgeon and anaesthetist you take it; no stop-time has been established.
Medicines broken down by CYP3A4 prescription	In human gut cells, huperzine A increased CYP3A4 through the pregnane X receptor, which could speed up the breakdown of some medicines.	Cell work only; no clinical interaction shown.	Laboratory research Very low certainty ²¹	Ask a pharmacist if you take medicines with narrow safety margins (for example some transplant, blood-thinning or HIV medicines).
Other 'brain' supplements and stimulants supplement	Many products are blends and some contain undeclared stimulants.	16 of 22 analysed products had unlabelled compounds.	Other Low certainty ²	Avoid stacking products; check ingredient lists with a pharmacist.
Antipsychotic medicines prescription	Trials in China added huperzine A to antipsychotics.	The meta-analysis reported similar adverse events to comparators.	Meta-analysis Low certainty ²²	Only under psychiatric supervision.

Who should check first 8

Situation	Advice	Evidence
Pregnancy or breastfeeding	Avoid. No human safety data; a lab study of the club-moss family raised birth-defect concern (summary-only).	Laboratory research ²³
Slow heart rate, heart block, fainting spells	Ask a doctor first; cholinesterase blockers can slow the heart (class caution).	Pharmacological theory ⁸
Taking donepezil, galantamine or rivastigmine	Do not add huperzine A without the prescriber's agreement.	Pharmacological theory ⁸
Asthma, COPD, stomach ulcer, epilepsy, bladder blockage	Class cautions for cholinesterase blockers (not tested for huperzine A); ask a doctor first.	Pharmacological theory
Planned surgery or anaesthesia	Tell the surgical team; no stop-time has been established.	Pharmacological theory ¹⁵
Children and teenagers	Avoid. One four-week teen trial exists but safety in young people is not established.	Controlled trial ¹⁴
Memory loss or confusion that has not been checked by a doctor	Get it assessed first; do not self-treat.	Systematic review ^{8 19}
Inhaling spore powder	Do not breathe lycopodium powder (including for fire effects).	Case report ¹⁰

Overdose, product quality and regulators

Summary. Overdose of a cholinesterase blocker causes excess acetylcholine effects (heavy sweating, vomiting, slow pulse, muscle weakness). We found no human case of huperzine A poisoning in PubMed searches. A lab study (read in summary) found club-moss alkaloid fractions toxic to nerve cells and fish embryos.

Animal. A 2021 study on mouse nerve cells and zebrafish embryos found toxicity of Lycopodiaceae alkaloid fractions (heart-sac swelling, tail defects). It is mostly about Huperzia serrata for birth defects. Not re-opened; details from our earlier summary.

Human doses studied. Trials used small daily amounts of purified huperzine A in the microgram to sub-milligram range (see study records); this page gives no dose advice. A cocaine-lab study tested up to 0.8 mg and called it safe and tolerated.

High dose or long term signals. Long-term safety (years) has not been studied in the trials we read. The longest were about 16 weeks.

Overdose response. Not documented in the sources read; class effects would be expected.

Genotoxicity. Not found.

Toxic plant parts. Not established. Huperzine A is found in the whole Huperzia serrata plant (Qian Ceng Ta). Lycopodium spores are a lung hazard if inhaled.

Product quality is a main issue for supplements: label amounts and ingredients are unreliable in the one analysis we found.

Label versus contents. Only 2 of 22 products were within 10% of the declared huperzine A; the amount ranged from not quantifiable up to 267.1 microgram per serving. ²

Undeclared ingredients. 16 of 22 contained unlabelled compounds, including stimulants (such as higenamine, vinpocetine, hordenine); 9 listed ingredients that do not meet FDA dietary-supplement rules. ²

Body	Action	Date
China (drug regulator) (China)	Huperzine A is marketed in China as a drug for Alzheimer's disease; a derivative (ZT-1) was in development (2007 review). In 2004 it was reported to be in phase III trials in China. source	2007

When to get medical help

Very slow pulse, fainting, chest pain or severe dizziness after taking it: stop it and call emergency services.
Heavy sweating, drooling, repeated vomiting or diarrhoea, or muscle weakness or twitching that does not settle: stop it and get urgent medical help.
Wheezing or trouble breathing (especially if you have asthma): stop it and get urgent help.
Cough, fever or shortness of breath after breathing in spore powder: see a doctor and tell them what was inhaled.
Pregnant or possibly pregnant and you took it: speak to your doctor or midwife.

Stop the supplement and contact a clinician or emergency service. In the US, Poison Control is 1-800-222-1222.

General information only, not medical advice. Ask a clinician or pharmacist before use, especially with medicines, in pregnancy or with a health condition. See the Natural Remedy Safety guide.

Frequently asked questions

What is clubmoss?

The name covers two different plants. Chinese club moss (Huperzia serrata, qian ceng ta) is the source of huperzine A, which is sold as a memory supplement. Common clubmoss (Lycopodium clavatum) gives the yellow spore powder called lycopodium powder. Do not assume what is true for one is true for the other.

^{5 6 9}

What is huperzine A?

A natural compound from Chinese club moss that blocks the enzyme acetylcholinesterase, raising the brain messenger acetylcholine. It works in the same way as the Alzheimer's medicines donepezil, galantamine and rivastigmine. It is marketed in China as an Alzheimer's drug.

^{9 8}

Does huperzine A help Alzheimer's disease?

It is not proven. Cochrane (2008) found small trials with better scores but said most were low quality and the evidence was inadequate to recommend it. The best-designed US trial (210 people) did not show a benefit at the lower dose in its main test.

^{8 13 18}

What happened in the US trial?

A trial titled 'A phase II trial of huperzine A in mild to moderate Alzheimer disease' (Neurology, 2011) compared two dose levels with placebo for at least 16 weeks. The planned main test was negative. The higher dose improved one score at week 11 but not significantly by week 16. It was co-funded by the NIH and a company.

¹³

Does it help mild memory problems or brain injury?

Cochrane found no trials in mild cognitive impairment, and a US phase II pilot after brain injury found no difference from placebo.

^{19 20}

What are the side effects?

As a cholinesterase blocker it can cause nausea, vomiting, diarrhoea, sweating, a slow heartbeat and muscle twitching. In short trials, side effects were reported as mild or absent, but the trials were small and low quality.

^{8 18 15}

Can I take it with donepezil or other Alzheimer's medicines?

Do not combine them without the prescriber's agreement. Both act on the same enzyme and effects could add up. We found no trial of the combination, so the size of the risk is unknown.

⁸

Does it interact with heart or bladder medicines?

Possibly. Cholinesterase blockers can slow the heart, so beta blockers and similar drugs may add to that. Anticholinergic drugs (some bladder, allergy and sleep medicines) pull the other way and may cancel it out. These are class-based cautions; no huperzine A case reports were found.

⁸

What about surgery?

Tell the surgeon and anaesthetist. Cholinesterase blockers can change how muscle-relaxing drugs work, and huperzine A stays in the body for many hours (half-life about 12 hours in healthy men).

¹⁵

Is it safe in pregnancy or breastfeeding?

Avoid it. There are no human safety data, and a laboratory study of the club-moss family found alkaloid fractions harmful to fish embryos and nerve cells, with the strongest birth-defect signal from Huperzia serrata.

²³

Do supplements contain what the label says?

Often not. In a 2020 analysis of 22 US products, only two had the labelled huperzine A within 10%, and 73% contained unlabelled compounds, including stimulants.

Is lycopodium powder safe to breathe?

No. One case report describes lung inflammation with granulomas after a man inhaled the spores while fire-breathing.

¹⁰

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Editorial transparency

Written by: AlternativeMed editorial team. Research compiled with AI assistance, then checked against PubMed records.
Medical review: None. This page has not been reviewed by a physician or pharmacist.
First published: 2026-10-25
Last substantive update: 2026-10-25
How we research: We started from the nutrient summary we hold, read PubMed abstracts, and checked GBIF, NCBI Taxonomy and PubChem. Full texts, LiverTox, LactMed, EMA and FDA records were not read. Certainty ratings are our own reading. No study is cited that we could not verify.
How we rate evidence: See "How we rate evidence" in the Evidence tab.
Independence: No product is promoted on this page. No affiliate links are shown.

Sources 23

Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.

(no authors listed). Huperzine A. Drugs R D. 2004. PMID 14725492. DOI 10.2165/00126839-200405010-00009. (abstract)
Crawford C, Wang YH, Avula B, et al.. The scoop on brain health dietary supplement products containing huperzine A. Clin Toxicol (Phila). 2020. PMID 31990212. DOI 10.1080/15563650.2020.1713337. (abstract)
De La Garza R 2nd, Verrico CD, Newton TF, et al.. Safety and Preliminary Efficacy of the Acetylcholinesterase Inhibitor Huperzine A as a Treatment for Cocaine Use Disorder. Int J Neuropsychopharmacol. 2015. PMID 26364275. DOI 10.1093/ijnp/pyv098. (abstract)
Desilets AR, Gickas JJ, Dunican KC.. Role of huperzine a in the treatment of Alzheimer's disease. Ann Pharmacother. 2009. PMID 19240260. DOI 10.1345/aph.1L402. (abstract)
GBIF. GBIF backbone: Huperzia serrata (Thunb.) Trevis. (key 2688470). GBIF species match API. 2026. (full-text)
GBIF. GBIF backbone: Lycopodium clavatum L. (key 2688393). GBIF species match API. 2026. (full-text)
Hao Z, Liu M, Liu Z, et al.. Huperzine A for vascular dementia. Cochrane Database Syst Rev. 2009. PMID 19370686. DOI 10.1002/14651858.CD007365.pub2. (abstract)
Li J, Wu HM, Zhou RL, et al.. Huperzine A for Alzheimer's disease. Cochrane Database Syst Rev. 2008. PMID 18425924. DOI 10.1002/14651858.CD005592.pub2. (abstract)
Ma X, Tan C, Zhu D, et al.. Huperzine A from Huperzia species - an ethnopharmacolgical review. J Ethnopharmacol. 2007. PMID 17644292. DOI 10.1016/j.jep.2007.05.030. (abstract)
Morresi-Hauf A, Neher A, Wockel W, et al.. Granulomatous bronchiolitis due to aspiration of lycopodium spores by fire-breathing. Pneumologie. 2009. PMID 18777466. DOI 10.1055/s-2008-1038256. (abstract)
NCBI PubChem. PubChem: huperzine A (CID 854026). PubChem PUG REST. 2026. (full-text)
NCBI PubChem. PubChem: lycopodine (CID 5462445). PubChem PUG REST. 2026. (full-text)
Rafii MS, Walsh S, Little JT, et al.. A phase II trial of huperzine A in mild to moderate Alzheimer disease. Neurology. 2011. PMID 21502597. DOI 10.1212/WNL.0b013e318216eb7b. (abstract)
Sun QQ, Xu SS, Pan JL, et al.. Huperzine-A capsules enhance memory and learning performance in 34 pairs of matched adolescent students. Zhongguo Yao Li Xue Bao (Acta Pharmacologica Sinica). 1999. PMID 10678121. (abstract)
Wu SL, Gan J, Rao J, et al.. Pharmacokinetics and tolerability of oral dosage forms of huperzine a in healthy Chinese male volunteers: a randomized, single dose, three-period, six-sequence crossover study. J Huazhong Univ Sci Technol Med Sci. 2017. PMID 29058298. DOI 10.1007/s11596-017-1807-8. (abstract)
Xu SS, Gao ZX, Weng Z, et al.. Efficacy of tablet huperzine-A on memory, cognition, and behavior in Alzheimer's disease. Zhongguo Yao Li Xue Bao (Acta Pharmacologica Sinica). 1995. PMID 8701750. (abstract)
Xu ZQ, Liang XM, Juan-Wu, et al.. Treatment with Huperzine A improves cognition in vascular dementia patients. Cell Biochem Biophys. 2012. PMID 21833673. DOI 10.1007/s12013-011-9258-5. (abstract)
Yang G, Wang Y, Tian J, et al.. Huperzine A for Alzheimer's disease: a systematic review and meta-analysis of randomized clinical trials. PLoS One. 2013. PMID 24086396. DOI 10.1371/journal.pone.0074916. (abstract)
Yue J, Dong BR, Lin X, et al.. Huperzine A for mild cognitive impairment. Cochrane Database Syst Rev. 2012. PMID 23235666. DOI 10.1002/14651858.CD008827.pub2. (abstract)
Zafonte RD, Fregni F, Bergin MJG, et al.. Huperzine A for the treatment of cognitive, mood, and functional deficits after moderate and severe TBI (HUP-TBI): results of a Phase II randomized controlled pilot study: implications for understanding the placebo effect. Brain Inj. 2020. PMID 31638455. DOI 10.1080/02699052.2019.1677941. (abstract)
Zhang YW, Bao MH, Wang G, et al.. Induction of human CYP3A4 by huperzine A, ligustrazine and oridonin through pregnane X receptor-mediated pathways. Pharmazie. 2014. PMID 25073399. (abstract)
Zheng W, Xiang YQ, Li XB, et al.. Adjunctive huperzine A for cognitive deficits in schizophrenia: a systematic review and meta-analysis. Hum Psychopharmacol. 2016. PMID 27302211. DOI 10.1002/hup.2537. (abstract)
not recorded (summary only). Toxicity Evaluation of Lycopodiaceae Extracts on Mouse Neuronal Cells and Zebrafish Embryos. VNU Journal of Science: Natural Sciences and Technology. 2021. (summary-only)

Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.