Vitamins & Supplements · Nootropic
Huperzine A and other herbal cholinesterase products
Huperzine A (from Huperzia serrata) · also called Chinese club moss extract, Huperzina A
Huperzine A is a compound from a Chinese club moss, sold as a memory supplement. It blocks the same brain enzyme as some prescription dementia medicines. Trials were mostly in people with Alzheimer's disease and were small, mixed and often poor quality. The main caution is that it may clash with dementia medicines, and supplement labels often do not match what is inside.
General information, not medical advice. Last substantive update · Not medically reviewed. A named clinician has not signed off on this page. How this page is made
About Huperzine A and other herbal cholinesterase products
Huperzine A is a compound from the Chinese club moss Huperzia serrata. It is sold for memory. Studies were mostly in people with Alzheimer's disease and gave mixed, mostly low-quality results.
What huperzine A is
Huperzine A is a compound obtained from a Chinese herb, Huperzia serrata. Researchers describe it as a reversible blocker of acetylcholinesterase, the enzyme that breaks down acetylcholine, a messenger in the brain.
Galantamine, a prescription medicine for Alzheimer's symptoms, is in the same class of medicines, called acetylcholinesterase inhibitors (MedlinePlus). That shared action is why a supplement and a medicine can raise questions when used together.
What the research found
The 2008 Cochrane review pooled 6 trials (454 people with Alzheimer's disease) and found better scores on some tests than placebo. It also said only one study was of adequate quality and size, so the evidence was inadequate to recommend use. A 2013 review of 20 trials (1,823 people) found similar gains but most trials had a high risk of bias.
A 210-person US trial in mild to moderate Alzheimer's disease did not find a change in its main test with the lower study amount. A higher study amount looked better at 11 weeks but not clearly at 16 weeks.
For mild cognitive impairment, Cochrane found no eligible trials. For healthy adults, no usable trial was found. For schizophrenia, 12 trials in China suggested possible gains when huperzine A was added to medicine. A small brain-injury trial found no difference from placebo.
What is in the bottle
A laboratory study of 22 supplements that listed huperzine A found that 73% had a labelled ingredient it could not detect and 73% contained compounds not on the label. Only two had huperzine A within 10% of the declared amount.
In the US, the FDA does not approve supplements for safety before sale (NCCIH). So the product you buy may not match the one that was studied.
At a glance
Traditional uses history, not proof
- A compound from the Chinese herb Huperzia serrata
- Sold as a supplement for memory and focus
Studied for research
- Thinking scores in Alzheimer's disease, low certainty
- Memory in healthy adults, insufficient evidence
Main compounds
- Huperzine A
- Huperzia serrata extract
Common forms
- Capsules or tablets of huperzine A
- Whole-plant extracts and brain-formula blends
Research links: 2008 Cochrane review: huperzine A for Alzheimer's disease (6 trials) · 2013 review: huperzine A for Alzheimer's disease (20 trials) · 2011 US trial of huperzine A in Alzheimer's disease (210 people) · 2020 laboratory analysis of 22 huperzine A supplements · 2012 Cochrane review: huperzine A for mild cognitive impairment · Research Library · Genes & Biomarkers Library
What it is and its history
- Accepted scientific name
- Huperzine A (a compound obtained from the club moss Huperzia serrata)
- Common names
- Huperzine A (English); Chinese club moss extract (English); Huperzina A (Spanish)
- Family or group
- Alkaloid obtained from a club moss. Trial papers call the plant a Chinese herb.
- Classification
- Huperzia > Huperzia serrata
- Native range
- Not looked up.
- Look-alikes and adulterants
- Name: Huperzia serrata plant extract; Note: A whole-plant extract; huperzine A content varies and was not compared with purified huperzine A in the sources read.; Name: Blends in brain formulas; Note: Often combined with other ingredients, which makes the effect of each unclear.
- Sustainability and conservation
- Not assessed.
What is inside, and how it may work
What it 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 | alkaloid | Not stated in the sources read Product content varied from below measurable up to 267.1 micrograms per serving in 22 products tested. | Described as a potent, reversible acetylcholinesterase inhibitor that crosses the blood-brain barrier. 8 4 1 | Human data |
| Huperzia serrata extract | plant extract | Not stated Not read from a source. | An extract described in a Japanese open-label study as acting as a cholinesterase inhibitor and glutamate receptor blocker. 7 | Human data |
Mechanisms, receptors and pathways
| Target or pathway | Gene or receptor | What was found | Level |
|---|---|---|---|
| Acetylcholinesterase (the enzyme that breaks down acetylcholine) | Not specified in the sources read | Described as a linearly competitive, reversible inhibitor of the enzyme (Cochrane background). Blocking it should leave more acetylcholine available between nerve cells. 4 8 | Human data |
| Glutamate receptors (possible) | Not specified | The Japanese open-label study describes Huperzia serrata extract as a glutamate receptor blocker too. This was stated, not tested in that study. 7 | Unclear |
| Protection of cells in the lab (possible) | Not specified | The Cochrane background says huperzine A is said to protect cells in the lab against beta-amyloid, glutamate and other toxins. This is lab or animal work, not shown in people. 4 | Lab |
Absorption, metabolism and elimination
- Absorption
- Taken by mouth; blood levels were measured over 72 hours in healthy men. Peak level about 1.55 ng/mL for the reference formulation.
- Distribution
- Described as crossing the blood-brain barrier.
- Metabolism
- Not described in the sources read.
- Elimination
- Half-life about 12.1 hours in healthy Chinese men (reference formulation).
- Bioavailability
- Three formulations were bioequivalent in fasting healthy men.
Isolated compounds versus whole extracts
Trials mostly used purified huperzine A. Plant extracts and blends are different products. In the 22 products tested, content varied widely, so the whole product cannot be assumed to match what was studied.
Nutritional composition
Huperzine A is not a food nutrient and has no food-source or recommended-intake figures. Nothing is stated about food amounts.
1 moderate certainty1 mixed findings4 low certainty1 very low certainty3 not enough evidence1 evidence against
What was looked at
The 11 benefits and uses checked for Huperzine A and other herbal cholinesterase products, each with how strong the evidence is. Tap one to open it.
- Slows the breakdown of acetylcholineModerate certainty
- Thinking scores in Alzheimer's diseaseLow certainty
- Daily activities in Alzheimer's diseaseLow certainty
- A larger US trial: mixed resultMixed findings
- Mild cognitive impairment (before dementia)Not enough evidence
- Memory or focus in healthy adultsNot enough evidence
- Thinking problems in schizophrenia (added to antipsychotics)Low certainty
- Memory after moderate to severe brain injuryEvidence against
- A blend with curcumin (open-label, no placebo)Very low certainty
- Other herbal 'natural cholinesterase' productsNot enough evidence
- How well it was tolerated in trialsLow certainty
Lab markers tracked in the studies
Mini-Mental State Examination (MMSE) scoreADAS-Cog scoreActivities of daily living (ADL) scoreMemory quotient (MQ)Schizophrenia symptom total (PANSS or BPRS)Wechsler Memory Scale-Revised memory quotientTime the compound stays in the body (half-life)
What is Huperzine A and other herbal cholinesterase products good for?
The main studied uses and how strong the human evidence is for each. Almost all results are in people who already have a memory disease, and none show that it helps healthy people.
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.
Slows the breakdown of acetylcholine
Moderate certaintyHuperzine A is described as a reversible blocker of acetylcholinesterase, the enzyme that breaks down the brain messenger acetylcholine. Some prescription Alzheimer's medicines act on the same enzyme. This describes how it acts. It does not show that it helps memory.
3 studiesPurified huperzine A and Huperzia serrata extracts. Supplement conten…
Studies, doses and limits
What the trials found
The 2008 Cochrane review describes huperzine A as a reversible inhibitor of acetylcholinesterase. A 2017 study in healthy volunteers calls it a potent, reversible inhibitor that crosses the blood-brain barrier. MedlinePlus says galantamine, a prescription medicine, belongs to the same class. No source read measured acetylcholine levels in people taking huperzine A supplements.
Results
The action is well described. It tells us why the questions about dementia medicines matter, not whether a supplement helps.
Effect sizes as reported
No effect sizes apply: this is how the compound acts, not a trial result.
Why this rating
Moderate that it blocks the enzyme (stated in review and human drug-level papers). It says nothing about benefit.
Form and dose studied
Purified huperzine A and Huperzia serrata extracts. Supplement content varies (see Safety).
Who was studied
General description; not specific to a group.
Limits
Descriptions come from review background text and a drug-levels study. Enzyme activity in people on supplements was not read.
Why researchers looked
Alzheimer's disease involves loss of acetylcholine-making nerve cells, so blocking the enzyme that clears acetylcholine has been a treatment idea for decades.
Traditional use
Huperzine A is a compound from a Chinese herb, Huperzia serrata. Several trials describe it as a natural cholinesterase inhibitor. Being studied is not the same as being shown to work.
Proposed mechanism Established pharmacology
A Cochrane review background and a human drug-levels study both describe huperzine A as a reversible acetylcholinesterase inhibitor that reaches the brain. MedlinePlus lists galantamine as another acetylcholinesterase inhibitor.
A proposed mechanism does not show that the effect happens in people.
Because it acts on the same enzyme as dementia medicines, mixing them is a question for a prescriber or pharmacist.
Thinking scores in Alzheimer's disease
Low certaintyIn small trials in people with Alzheimer's disease, huperzine A improved some thinking-test scores against placebo. The 2008 Cochrane review (6 trials, 454 people) found the evidence inadequate to recommend its use. A 2013 review of 20 trials (1,823 people) found similar gains but said most trials were at high risk of bias.
2 studiesPurified huperzine A tablets or capsules, mostly from trials in China.
Studies, doses and limits
What the trials found
Cochrane 2008: compared with placebo, MMSE was better by 2.81 points (95% CI 1.87 to 3.76), ADAS-Cog by 1.91 at 6 weeks and 2.51 at 12 weeks. It was not better on the Hasegawa Dementia Scale or the Wechsler Memory Scale. The authors say only one trial was of adequate quality and size. The 2013 review (20 trials) found MMSE gains at 8, 12 and 16 weeks but said most trials had a high risk of bias, and one trial found no change on ADAS-Cog.
Results
Some scores improved in small, mostly poor-quality trials. The reviewers do not call it proven. Results are for people with Alzheimer's disease only.
Effect sizes as reported
Cochrane 2008: MMSE WMD 2.81 (1.87 to 3.76); ADAS-Cog WMD 1.91 (1.27 to 2.55) at 6 weeks and 2.51 (1.74 to 3.28) at 12 weeks.
Why this rating
Low: the Cochrane authors found the evidence inadequate to recommend use, and the 2013 authors rated most trials as high risk of bias.
Form and dose studied
Purified huperzine A tablets or capsules, mostly from trials in China.
Who was studied
Adults with Alzheimer's disease of mild to moderate degree.
Limits
Small trials, mostly poor quality, mostly short (6 to 16 weeks). Not applicable to healthy adults. Abstracts read only.
Why researchers looked
Alzheimer's disease causes memory and thinking loss, and huperzine A is sold as a natural option.
Traditional use
Huperzine A is a compound from a Chinese herb, Huperzia serrata. Several trials describe it as a natural cholinesterase inhibitor. Being studied is not the same as being shown to work.
Proposed mechanism Established pharmacology
Huperzine A blocks acetylcholinesterase (see the first item). Whether this gives a lasting benefit in trials is the question these reviews ask.
A proposed mechanism does not show that the effect happens in people.
Mild side effects, no severe ones reported in the trials; the trials were small and short.
Daily activities in Alzheimer's disease
Low certaintySome trials found better scores for everyday activities (such as dressing and managing money) with huperzine A. Most of those trials were poor quality, and no trial measured quality of life.
3 studiesPurified huperzine A.
Studies, doses and limits
What the trials found
Cochrane 2008 found daily-living scores (ADL) better with huperzine A than placebo (WMD -7.17, 95% CI -9.13 to -5.22). The 2013 review found ADL results favoured huperzine A at 6, 12 and 16 weeks, but one trial found no change on the ADCS-ADL. Neither review found a trial of quality of life. The larger US trial found no significant change in daily living at either study amount.
Results
A possible small gain in poor-quality trials, not seen in the best-run US trial.
Effect sizes as reported
Cochrane 2008: ADL WMD -7.17 (-9.13 to -5.22).
Why this rating
Low: poor-quality trials in the reviews, and the larger US trial did not find a significant change.
Form and dose studied
Purified huperzine A.
Who was studied
Adults with Alzheimer's disease.
Limits
Different ADL scales were used. Trials mostly small and short.
Why researchers looked
Daily living is what matters most to families, so reviews check it as well as test scores.
Traditional use
Huperzine A is a compound from a Chinese herb, Huperzia serrata. Several trials describe it as a natural cholinesterase inhibitor. Being studied is not the same as being shown to work.
Proposed mechanism Not established
Not established. The reviews do not give a mechanism for this result.
A proposed mechanism does not show that the effect happens in people.
See Safety.
A larger US trial: mixed result
Mixed findingsIn a 210-person US trial in mild to moderate Alzheimer's disease, the lower study amount did not change the main thinking score at 16 weeks. The higher study amount looked better at 11 weeks, but at 16 weeks the gap was no longer clear.
1 studiesPurified huperzine A capsules at two study amounts (trial amounts, no…
Studies, doses and limits
What the trials found
210 people were randomised to placebo, a lower or a higher study amount for at least 16 weeks; 177 finished. The lower amount did not change ADAS-Cog at 16 weeks (the main test). For the higher amount, ADAS-Cog improved 2.27 points at 11 weeks against a 0.29-point decline on placebo (p = 0.001), but at week 16 it was 1.92 against 0.34 points (p = 0.07). Global change, behaviour and daily-living scores were not significant at either amount. The authors classed it as Class III evidence of no demonstrable thinking effect at the lower amount.
Results
The main test was negative; one secondary result was positive at 11 weeks and faded by 16 weeks. This is why overall evidence is called mixed.
Effect sizes as reported
Higher amount, ADAS-Cog: 2.27 vs -0.29 points at 11 weeks (p = 0.001); 1.92 vs 0.34 points at 16 weeks (p = 0.07).
Why this rating
Mixed: a negative main result with one secondary result that faded. Funding was from NIH per the PubMed record.
Form and dose studied
Purified huperzine A capsules at two study amounts (trial amounts, not advice).
Who was studied
Adults with mild to moderate Alzheimer's disease.
Limits
Secondary analyses are weaker than a main result; only 16 weeks; abstract read only.
Why researchers looked
The best-designed trial of huperzine A so far was run by a US research group to test the earlier small trials.
Traditional use
Huperzine A is a compound from a Chinese herb, Huperzia serrata. Several trials describe it as a natural cholinesterase inhibitor. Being studied is not the same as being shown to work.
Proposed mechanism Not established
Not established. The trial did not test a mechanism.
A proposed mechanism does not show that the effect happens in people.
Side-effect numbers were not in the abstract.
Mild cognitive impairment (before dementia)
Not enough evidenceA 2012 Cochrane review found no eligible placebo-controlled trials in mild cognitive impairment, so it could not judge huperzine A. A 2019 Chinese review of 9 trials reported better memory and MMSE scores than placebo but called the original studies low quality.
2 studiesPurified huperzine A.
Studies, doses and limits
What the trials found
Cochrane 2012: no eligible trials; evidence insufficient. The 2019 review (9 randomised trials, article in Chinese, English abstract read) reported that, against placebo, huperzine A raised memory quotient and MMSE, with no difference between tablets and capsules and mild side effects. The abstract gives no numbers and says better studies are needed.
Results
Not enough to say. The newer review hints at benefit but rates its own source studies low quality.
Effect sizes as reported
No numbers available in either abstract.
Why this rating
Insufficient: Cochrane found no eligible trials; the 2019 review's studies were low quality.
Form and dose studied
Purified huperzine A.
Who was studied
Adults with mild cognitive impairment.
Limits
Chinese-language review; only the abstract was read. The Cochrane search ended in 2011.
Why researchers looked
Some people with mild memory problems look for something to slow decline.
Traditional use
Huperzine A is a compound from a Chinese herb, Huperzia serrata. Several trials describe it as a natural cholinesterase inhibitor. Being studied is not the same as being shown to work.
Proposed mechanism Not established
Not established.
A proposed mechanism does not show that the effect happens in people.
Side effects were reported as mild in the 2019 review.
Memory or focus in healthy adults
Not enough evidenceNo good evidence was found that huperzine A improves memory or focus in healthy adults. One small 1999 trial in school students who complained of poor memory reported a higher memory score after four weeks. It has not been confirmed.
2 studiesHuperzine A capsules (trial amount shown in the studies table).
Studies, doses and limits
What the trials found
A 1999 trial in China matched 34 pairs of junior middle school students who complained of poor memory. After 4 weeks the huperzine A group's memory quotient was 115 versus 104 on placebo (p < 0.01), and Chinese-language scores were higher. The abstract does not report side effects. The 2023 review of over-the-counter memory supplements lists huperzine A among ingredients with mixed results. No randomised trial in healthy adults was found in the searches done.
Results
No usable evidence for healthy adults. The one small study was in students with memory complaints, not adults.
Effect sizes as reported
Memory quotient 115 +/- 6 vs 104 +/- 9 (p < 0.01), one small trial.
Why this rating
Insufficient: one small, old, unreplicated trial in students; nothing in healthy adults.
Form and dose studied
Huperzine A capsules (trial amount shown in the studies table).
Who was studied
School students with memory complaints (not adults).
Limits
Very small trial from 1999; abstract only; no follow-up. Alzheimer's results cannot be applied to healthy people.
Why researchers looked
Brain supplements are marketed to healthy people for memory and focus.
Traditional use
Huperzine A is a compound from a Chinese herb, Huperzia serrata. Several trials describe it as a natural cholinesterase inhibitor. Being studied is not the same as being shown to work.
Proposed mechanism Not established
Not established.
A proposed mechanism does not show that the effect happens in people.
A lack of reported problems in a small, short trial is not proof of safety.
Thinking problems in schizophrenia (added to antipsychotics)
Low certaintyA 2016 review of 12 trials (1,117 people, all in China) found huperzine A added to antipsychotic medicine did better than comparison on memory scores, IQ-type tests and symptom totals. Side effects and dropouts were similar. The authors say better-designed trials are needed.
1 studiesPurified huperzine A added to antipsychotics.
Studies, doses and limits
What the trials found
The review pooled 12 randomised trials of huperzine A added to antipsychotic treatment, lasting about 12 weeks on average. Wechsler Memory Scale-Revised memory quotient: WMD 10.59 (95% CI 5.65 to 15.53). Symptom total scores (PANSS or BPRS): SMD -0.77 (-1.27 to -0.27). All-cause dropout: RR 0.67 (0.36 to 1.24), not significant. Adverse events were similar between groups.
Results
A possible gain on some tests when added to medicine, from trials all done in one country. It is not a treatment on its own. People with schizophrenia should not change medicines without their doctor.
Effect sizes as reported
Memory quotient WMD 10.59 (5.65 to 15.53); symptoms SMD -0.77 (-1.27 to -0.27); dropouts RR 0.67 (0.36 to 1.24).
Why this rating
Low: all trials were done in China, trial quality is not stated in the abstract, and the authors ask for better-designed trials.
Form and dose studied
Purified huperzine A added to antipsychotics.
Who was studied
Adults with schizophrenia spectrum disorders.
Limits
All trials from one country; comparators varied; abstract read only.
Why researchers looked
Thinking problems are common in schizophrenia and current medicines do little for them.
Traditional use
Huperzine A is a compound from a Chinese herb, Huperzia serrata. Several trials describe it as a natural cholinesterase inhibitor. Being studied is not the same as being shown to work.
Proposed mechanism Not established
Not established in the abstract. The review does not test a mechanism.
A proposed mechanism does not show that the effect happens in people.
Adverse events were similar to comparison, but a medicine that acts on acetylcholine may interact with antipsychotics (ask a prescriber).
Memory after moderate to severe brain injury
Evidence againstA small US pilot trial found no difference between huperzine A and placebo for memory after moderate to severe brain injury. Both groups improved, which the authors put down to a placebo effect.
1 studiesPurified huperzine A.
Studies, doses and limits
What the trials found
In a 12-week randomised, double-blind pilot, there was no difference between huperzine A and placebo on a verbal learning and memory test. Both groups improved in memory and depression scores. The number of people is not in the abstract.
Results
No benefit shown over placebo in this trial.
Effect sizes as reported
No difference between groups; no numbers in the abstract.
Why this rating
Against: a placebo-controlled trial found no difference. It was a small pilot.
Form and dose studied
Purified huperzine A.
Who was studied
Adults with moderate to severe traumatic brain injury.
Limits
Pilot-size trial; number of people not in the abstract.
Why researchers looked
Memory problems after brain injury are common and hard to treat.
Traditional use
Huperzine A is a compound from a Chinese herb, Huperzia serrata. Several trials describe it as a natural cholinesterase inhibitor. Being studied is not the same as being shown to work.
Proposed mechanism Not established
Not established.
A proposed mechanism does not show that the effect happens in people.
Not described in the abstract.
A blend with curcumin (open-label, no placebo)
Very low certaintyA Japanese open-label study of a blend of Huperzia serrata extract, curcumin and other ingredients reported better thinking scores than at the start. There was no placebo group, so the change cannot be credited to the blend.
1 studiesA multi-ingredient blend containing Huperzia serrata extract and curc…
Studies, doses and limits
What the trials found
People with Alzheimer's disease, dementia with Lewy bodies and mild cognitive impairment took the blend and were scored with a Japanese version of ADAS-Cog. Scores improved against their own starting scores at 6 to 12 weeks (p = 0.007) and at 22 to 28 weeks (p = 0.004). There was no control group and the number of people is not in the abstract.
Results
A starting-point comparison only. It cannot tell whether the blend, the placebo effect or time explains the change.
Effect sizes as reported
Better than baseline, p = 0.007 and p = 0.004; no control group.
Why this rating
Very low: uncontrolled, open-label, and a blend of ingredients.
Form and dose studied
A multi-ingredient blend containing Huperzia serrata extract and curcumin.
Who was studied
People with dementia or mild cognitive impairment in Japan.
Limits
No placebo; the effect of each ingredient cannot be separated.
Why researchers looked
Supplement companies often blend huperzine A with other ingredients.
Traditional use
Huperzine A is a compound from a Chinese herb, Huperzia serrata. Several trials describe it as a natural cholinesterase inhibitor. Being studied is not the same as being shown to work.
Proposed mechanism Not established
The authors describe the extract as a cholinesterase inhibitor and glutamate receptor blocker; the study did not test this.
A proposed mechanism does not show that the effect happens in people.
Not described.
Other herbal 'natural cholinesterase' products
Not enough evidenceLabels sometimes call other plant extracts 'natural acetylcholinesterase inhibitors'. No human trial of any such product was read for this page, so no claim is made for them.
2 studiesNot applicable.
Studies, doses and limits
What the trials found
The 2023 review of over-the-counter memory supplements surveyed 103 products and 18 common ingredients. It reports that huperzine A, ginkgo and a few others have mixed results for memory. The review's abstract does not describe cholinesterase-blocking claims for other plants, and no other trial of such a claim was read.
Results
Nothing to report. Ginkgo and bacopa have their own pages here.
Effect sizes as reported
No effect sizes.
Why this rating
Insufficient: no human trials read for these claims.
Limits
Absence of evidence is not evidence of safety or of no effect.
Why researchers looked
Shoppers meet this phrase on memory and focus supplements.
Traditional use
Huperzine A is a compound from a Chinese herb, Huperzia serrata. Several trials describe it as a natural cholinesterase inhibitor. Being studied is not the same as being shown to work.
Proposed mechanism Not established
Not established for these products.
A proposed mechanism does not show that the effect happens in people.
Blends may contain ingredients that are not on the label (see Safety).
How well it was tolerated in trials
Low certaintyIn the trials reviewed, side effects were described as mild and no severe ones were reported. A single-dose study in healthy volunteers also reported none. These trials were small and short.
4 studiesPurified huperzine A in trials.
Studies, doses and limits
What the trials found
Cochrane 2008: adverse events were mild and did not differ from placebo. The 2013 review: no trial reported severe adverse events. The schizophrenia review found side effects and dropouts similar between groups. In a 2017 study in healthy Chinese men, no adverse events were reported after a single dose of three formulations. The US trial's abstract does not give side-effect numbers.
Results
Short trials in carefully watched patients did not raise alarms. That does not show long-term safety, or safety of supplements bought online.
Effect sizes as reported
No frequencies given in the abstracts.
Why this rating
Low: small, short trials with limited side-effect reporting.
Form and dose studied
Purified huperzine A in trials.
Who was studied
Adults with Alzheimer's disease, schizophrenia, and healthy male volunteers.
Limits
Short follow-up; side effects are rarely reported in detail in abstracts.
Why researchers looked
People ask whether a natural cholinesterase blocker is gentle.
Traditional use
Huperzine A is a compound from a Chinese herb, Huperzia serrata. Several trials describe it as a natural cholinesterase inhibitor. Being studied is not the same as being shown to work.
Proposed mechanism Not established
Not applicable.
A proposed mechanism does not show that the effect happens in people.
A lack of reported problems in small trials is not proof of safety. See the Safety tab.
Connections to the rest of health
How Huperzine A and other herbal cholinesterase products 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
A. Wellness goals
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Memory Support | Moderate certainty | Slows the breakdown of acetylcholine: Huperzine A is described as a reversible blocker of acetylcholinesterase, the enzyme that breaks down the brain messenger acetylcholine. Some prescription Alzheimer's medicines act on the same enzyme. This describes how it acts. It does not show that it helps memory. | 4 8 13 | |
| Memory Support | Low certainty | Thinking scores in Alzheimer's disease: In small trials in people with Alzheimer's disease, huperzine A improved some thinking-test scores against placebo. The 2008 Cochrane review (6 trials, 454 people) found the evidence inadequate to recommend its use. A 2013 review of 20 trials (1,823 people) found similar gains but said most trials were at high risk of bias. Daily activities in Alzheimer's disease: Some trials found better scores for everyday activities (such as dressing and managing money) with huperzine A. Most of those trials were poor quality, and no trial measured quality of life. | 4 9 5 12 8 | |
| Memory Support | Mixed findings | A larger US trial: mixed result: In a 210-person US trial in mild to moderate Alzheimer's disease, the lower study amount did not change the main thinking score at 16 weeks. The higher study amount looked better at 11 weeks, but at 16 weeks the gap was no longer clear. Memory after moderate to severe brain injury: A small US pilot trial found no difference between huperzine A and placebo for memory after moderate to severe brain injury. Both groups improved, which the authors put down to a placebo effect. | 5 11 | |
| Memory Support | Not enough evidence | Mild cognitive impairment (before dementia): A 2012 Cochrane review found no eligible placebo-controlled trials in mild cognitive impairment, so it could not judge huperzine A. A 2019 Chinese review of 9 trials reported better memory and MMSE scores than placebo but called the original studies low quality. | 10 3 | |
| Memory Support | Not enough evidence | Memory or focus in healthy adults: No good evidence was found that huperzine A improves memory or focus in healthy adults. One small 1999 trial in school students who complained of poor memory reported a higher memory score after four weeks. It has not been confirmed. | 6 2 | |
| Memory Support | Very low certainty | A blend with curcumin (open-label, no placebo): A Japanese open-label study of a blend of Huperzia serrata extract, curcumin and other ingredients reported better thinking scores than at the start. There was no placebo group, so the change cannot be credited to the blend. | 7 | |
| Memory Support | Not enough evidence | Other herbal 'natural cholinesterase' products: Labels sometimes call other plant extracts 'natural acetylcholinesterase inhibitors'. No human trial of any such product was read for this page, so no claim is made for them. | 2 1 |
B. Body systems
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Brain | Biological association | Moderate certainty | Studied for: Slows the breakdown of acetylcholine Studied for: Thinking scores in Alzheimer's disease | 4 8 13 9 5 10 3 6 2 12 11 7 1 |
| Nervous System | Biological association | Moderate certainty | Studied for: Slows the breakdown of acetylcholine Studied for: Thinking scores in Alzheimer's disease | 4 8 13 9 5 10 3 6 2 12 11 7 1 |
E. Health conditions
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Alzheimer's disease | Preliminary | Small, mostly poor-quality trials gave mixed results; Cochrane found the evidence inadequate to recommend use. Preparation or compound: Huperzine A |
4 9 5 | |
| Mild cognitive impairment | Not enough evidence | Cochrane found no eligible trials; a 2019 Chinese review rated its source trials low quality. Preparation or compound: Huperzine A |
10 3 | |
| Schizophrenia | Preliminary | Twelve trials, all in China, with possible gains on some tests. Preparation or compound: Huperzine A added to antipsychotics |
12 | |
| Alzheimer's disease | Preliminary | Small, mostly poor-quality trials gave mixed results; Cochrane found the evidence inadequate to recommend use. Preparation or compound: Huperzine A |
4 9 5 | |
| Mild cognitive impairment | Not enough evidence | Cochrane found no eligible trials; a 2019 review rated its source trials low quality. Preparation or compound: Huperzine A |
10 3 |
I. Biomarkers
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Mini-Mental State Examination (MMSE) score | Biological association | Low certainty | Measured in trials: higher with huperzine A in small trials (low certainty). A lab change is not the same as a health benefit. | 4 9 |
| ADAS-Cog score | Biological association | Mixed findings | Measured in trials: better in small trials, unchanged in the main result of the US trial. A lab change is not the same as a health benefit. | 4 5 |
| Activities of daily living (ADL) score | Biological association | Low certainty | Measured in trials: better in poor-quality trials; not significant in the US trial. A lab change is not the same as a health benefit. | 4 5 |
| Memory quotient (MQ) | Biological association | Not enough evidence | Measured in trials: higher in small trials (very weak evidence). A lab change is not the same as a health benefit. | 6 3 |
| Schizophrenia symptom total (PANSS or BPRS) | Biological association | Low certainty | Measured in trials: lower with huperzine A in pooled trials (low certainty). A lab change is not the same as a health benefit. | 12 |
| Wechsler Memory Scale-Revised memory quotient | Biological association | Low certainty | Measured in trials: higher with huperzine A (low certainty). A lab change is not the same as a health benefit. | 12 |
| Time the compound stays in the body (half-life) | Biological association | Moderate certainty | Measured in trials: about 12 hours in healthy men. A lab change is not the same as a health benefit. | 8 |
J. Genes, receptors and enzymes
L. Active compounds
| Connected to | Kind of connection | Evidence status | Context | Studies |
|---|---|---|---|---|
| Huperzine A | Biological association | Human | Described as a potent, reversible acetylcholinesterase inhibitor that crosses the blood-brain barrier. | 8 4 1 |
| Huperzia serrata extract | Biological association | Human | An extract described in a Japanese open-label study as acting as a cholinesterase inhibitor and glutamate receptor blocker. | 7 |
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 26, 2026).
Evidence at a glance: what the research found for 11 outcomes
Each outcome below is one thing researchers measured. Certainty is how far the evidence can be trusted, not how well it works. The full studies are on the next tab.
The evidence
The research centre for Huperzine A and other herbal cholinesterase products. Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.
Evidence by outcome
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 our existing huperzine A summary, read the MedlinePlus galantamine page and the NCCIH page on using supplements wisely, and re-read PubMed abstracts for reviews, trials and a laboratory product analysis. Only abstracts were read for studies. A liver-safety page was blocked by a browser check and is marked unread.
Study library: every study we checked 14
| Study | Design | People | Product, dose, length | Result |
|---|---|---|---|---|
| Crawford 2020 The scoop on brain health dietary supplement products containing huperzine A. Clin Toxicol (Phila) · PMID 31990212 · DOI |
Laboratory product analysis product |
22 22 dietary supplement products that listed huperzine A on the label |
Commercial supplements · vs Label compared with laboratory analysis |
Sixteen of 22 products (73%) had at least one labelled ingredient that the analysis did not detect. Compounds not on the label were found in 16 products (73%). Nine products (41%) listed ingredients that do not meet FDA rules for a supplement ingredient. Stimulants of concern were found, including higenamine, vinpocetine, noopept and hordenine. Huperzine A ranged from below the quantifiable limit up to 267.1 micrograms per serving, and only two products were within 10% of the amount on the label. 16/22 products with an undetected labelled ingredient; 2/22 within 10% of the declared amount (Not applicable) Methods, limits and fundingOutcomes: Match between label and contents Limitations: 22 products from one search, a snapshot in time; product names not given in the abstract. Funding and conflicts: Authors from a US military medical school and a university; funding not stated in the abstract. Read: abstract |
| Hersant 2023 Over the Counter Supplements for Memory: A Review of Available Evidence. CNS Drugs · PMID 37603263 · DOI |
Narrative review |
Review of the 18 most common ingredients in 103 memory supplements sold in US pharmacies and groceries | Memory supplement ingredients, including huperzine A Mixed |
The review lists huperzine A, ginkgo, carnitine, vitamin D and vitamin E among ingredients with mixed results for memory. It notes that the FDA does not approve supplement safety, effectiveness or labels before sale, and calls for more rigorous long-term studies. No numbers for huperzine A in the abstract (Not applicable) Methods, limits and fundingOutcomes: Evidence for memory benefit by ingredient Limitations: A narrative review; huperzine A is one of 18 ingredients covered; abstract read only. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Huang 2019 [Efficacy and safety of huperzine A in treating patients with mild cognitive impairment: a systematic review and Meta-analysis]. Zhongguo Zhong Yao Za Zhi · PMID 30989926 · DOI |
Systematic review meta analysis |
People with mild cognitive impairment (9 trials) | Huperzine A (from Huperzia serrata) tablets or capsules Purified compound Not given in the abstract Not given in the abstract · vs Placebo |
Compared with placebo, huperzine A raised memory quotient and MMSE scores. No difference was found between tablet and capsule. Side effects were mild. The authors say the original studies were of low quality and better ones are needed. Direction only; no numbers in the abstract (Not given in the abstract) Methods, limits and fundingOutcomes: Memory quotient, MMSE, side effects Limitations: Article is in Chinese; only the English abstract was read. Study quality was low. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Li 2008 Huperzine A for Alzheimer's disease. Cochrane Database Syst Rev · PMID 18425924 · DOI |
Systematic review meta analysis |
454 People with Alzheimer's disease (6 trials) |
Huperzine A (from Huperzia serrata) tablets or capsules, trials in China Purified compound Different in each trial 6 to 12 weeks in the trials pooled · vs Placebo |
Compared with placebo, huperzine A improved some scores: MMSE, ADAS-Cog, CDR, CIBIC-plus, ADAS-non-Cog and ADL. It did not beat placebo on the Hasegawa Dementia Scale or the Wechsler Memory Scale. No data on quality of life or caregiver burden. Side effects were mild and did not differ from placebo. Only one study was of adequate quality and size, so the authors found the evidence inadequate to make any recommendation. 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; ADL -9.13 to -5.22) Methods, limits and fundingOutcomes: Thinking scores, global rating, behaviour, daily activities, side effects Limitations: Most trials were of modest quality; the search ended in 2006; abstract read only. Funding and conflicts: Authors declare no conflict of interest. Read: abstract |
| Rafii 2011 A phase II trial of huperzine A in mild to moderate Alzheimer disease. Neurology · PMID 21502597 · DOI |
Controlled trial |
210 People with mild to moderate Alzheimer's disease (177 finished the treatment phase) |
Huperzine A (from Huperzia serrata) capsules Purified compound Two study amounts: 200 micrograms twice daily and 400 micrograms twice daily (trial amounts, not advice) At least 16 weeks · vs Placebo |
The lower study amount did not change the main thinking score (ADAS-Cog) at 16 weeks. In a secondary analysis the higher study amount improved ADAS-Cog by 2.27 points at 11 weeks against a 0.29-point decline on placebo (p = 0.001), but at 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 amount. The authors classed the result as Class III evidence of no demonstrable thinking effect at the lower amount. Higher amount, ADAS-Cog: 2.27 vs -0.29 points at 11 weeks; 1.92 vs 0.34 at 16 weeks (p-values only (p = 0.001 and p = 0.07)) Methods, limits and fundingOutcomes: ADAS-Cog at week 16 (main), MMSE, global change, daily living, behaviour Limitations: Secondary analysis for the higher amount; side-effect numbers not in the abstract. Funding and conflicts: Research support from NIH (extramural) and non-US government sources per the PubMed record; no industry funding stated in the abstract. Read: abstract |
| Sun 1999 Huperzine-A capsules enhance memory and learning performance in 34 pairs of matched adolescent students. Zhongguo Yao Li Xue Bao · PMID 10678121 |
Controlled trial |
68 Junior middle school students complaining of poor memory (34 matched pairs) |
Huperzine A (from Huperzia serrata) capsules Purified compound Two capsules (50 micrograms each) twice daily (trial amount, not advice) 4 weeks · vs Placebo (starch and lactose) |
At the end of the trial the huperzine A group had a higher memory quotient than the placebo group (115 versus 104, p < 0.01) and higher Chinese-language scores. Memory quotient 115 +/- 6 vs 104 +/- 9 (p < 0.01) Methods, limits and fundingOutcomes: Memory quotient, school scores Limitations: Small, short trial from 1999 in students with memory complaints; not in adults; no repeat trial was found in the searches done. Abstract read only. Funding and conflicts: Not stated in the abstract. Read: abstract |
| Tabira 2018 A Study of a Supplement Containing Huperzine A and Curcumin in Dementia Patients and Individuals with Mild Cognitive Impairment. J Alzheimers Dis · PMID 29614668 · DOI |
Open label uncontrolled |
People with Alzheimer's disease, dementia with Lewy bodies, and mild cognitive impairment (Japan) | A blend of Huperzia serrata extract, curcumin and other ingredients Whole-plant extract in a blend Not given in the abstract Up to 28 weeks |
Most people had better thinking scores than at the start, at 6 to 12 weeks (p = 0.007) and at 22 to 28 weeks (p = 0.004). There was no control group, so the change cannot be credited to the supplement, and the product was a blend. Scores improved against baseline (p = 0.007 and p = 0.004) Methods, limits and fundingOutcomes: ADAS-Cog (Japanese version) Limitations: Open-label with no placebo group; combination product; number of people not in the abstract. Funding and conflicts: Not stated in the abstract. 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 Technolog Med Sci · PMID 29058298 · DOI |
Crossover pk study |
Healthy Chinese male volunteers, fasting | Huperzine A, three oral formulations Purified compound Single dose One dose per period · vs Reference formulation |
The drug stayed in the body with a half-life of about 12 hours (reference formulation 12.09 h; peak 1.55 ng/mL). The three formulations were bioequivalent. No adverse events were reported and all were well tolerated. This is a short, single-dose study in healthy men and says nothing about benefit. Half-life about 12.1 h; Cmax 1.550 ng/mL (reference) (90% CI for AUC and Cmax between 0.80 and 1.25) Methods, limits and fundingOutcomes: Blood levels over time, tolerability Limitations: Single dose, healthy young Chinese men only. Funding and conflicts: Not stated in the abstract. 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 |
Systematic review meta analysis |
1823 People with Alzheimer's disease (20 trials) |
Huperzine A (from Huperzia serrata), trials mostly in China Purified compound Different in each trial 6 to 16 weeks · vs Placebo, no treatment, psychotherapy or usual medicine |
Compared with placebo, huperzine A improved MMSE at 8, 12 and 16 weeks, and daily living scores at 6, 12 and 16 weeks. One trial found no change on ADAS-Cog or ADCS-ADL. No trial measured quality of life. No trial reported severe side effects. The authors say most trials had a high risk of bias and the findings need caution. Direction only in the abstract; no numbers given (Not given in the abstract) Methods, limits and fundingOutcomes: MMSE, Hasegawa scale, Wechsler Memory Scale, daily living, global rating, side effects Limitations: Poor method quality in most trials; abstract read only. Funding and conflicts: Authors declare no known conflicts of interest. 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 |
Huperzine A (from Huperzia serrata) Purified compound · vs Placebo |
No eligible randomised, placebo-controlled trials were found, so no meta-analysis was possible. The authors say the evidence is insufficient to judge huperzine A for mild cognitive impairment. No numbers: no trials found (Not applicable) Methods, limits and fundingOutcomes: Thinking scores, progression to dementia, side effects Limitations: Searched up to May 2011; trials published since are not covered. Abstract read only. Funding and conflicts: Authors declare none. 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 |
People with moderate to severe traumatic brain injury | Huperzine A (from Huperzia serrata) Purified compound Not given in the abstract 12 weeks · vs Placebo |
There was no difference between huperzine A and placebo in memory after 12 weeks. Both groups improved, and the authors say this is best understood as a placebo effect. Both groups also improved in depression scores. No difference between groups (Not given in the abstract) Methods, limits and fundingOutcomes: Memory and learning (CVLT-II), mood Limitations: Small pilot study; number of people not in the abstract. Funding and conflicts: Research support from NIH and US government sources per the PubMed record; no industry funding stated in the abstract. Read: abstract |
| Zheng 2016 Adjunctive huperzine A for cognitive deficits in schizophrenia: a systematic review and meta-analysis. Hum Psychopharmacol · PMID 27302211 · DOI |
Systematic review meta analysis |
1117 People with schizophrenia spectrum disorders taking antipsychotic medicines (12 trials, all in China) |
Huperzine A (from Huperzia serrata) added to antipsychotic treatment Purified compound Different in each trial About 12 weeks on average · vs Placebo or usual antipsychotic treatment alone |
Huperzine A added to antipsychotics did better than comparison on the Wechsler Memory Scale-Revised, IQ scores, the Wisconsin Card Sorting Test and symptom totals. Dropouts and side effects were similar between groups. The authors call for better-designed trials. Memory quotient WMD 10.59; symptom total SMD -0.77; dropouts RR 0.67 (Memory quotient 5.65 to 15.53; symptoms -1.27 to -0.27; dropouts 0.36 to 1.24) Methods, limits and fundingOutcomes: Memory, intelligence tests, card-sorting test, symptom scores, dropouts, side effects Limitations: All trials were in China; the abstract does not rate trial quality. Funding and conflicts: Not stated in the abstract. Read: abstract |
| s-medlineplus-galantamine MedlinePlus Drug Information: Galantamine (page last revised 2026-08-15) · Source |
Reference database n/a |
Methods, limits and fundingRead: full-text | ||
| s-nccih-supplements-wisely NCCIH: Using Dietary Supplements Wisely · Source |
Reference database n/a |
Methods, limits and fundingRead: full-text |
What we do not know yet
- No randomised trial in healthy adults was found.
- No study of huperzine A together with a dementia medicine was found.
- No pregnancy, breastfeeding or children's safety data were found.
- The liver-safety reference LiverTox could not be read, and no regulator statement on huperzine A was read.
- Trials were short (up to about 16 weeks); long-term effects are unknown.
How new research is added
New studies are found by a saved PubMed search and placed in a review queue before the page 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) score
Higher with huperzine A in small trials (low certainty) in trials
A 30-point quick test of memory, attention and orientation. A higher score means better thinking.
Low certaintyResults and what it means
Why it was measured
To see whether thinking test scores rise with huperzine A.
Statistical vs. clinical meaning
Most trials were poor quality, so the gain may be overstated.
Safety implication
Side effects were mild in these trials.
ADAS-Cog score
Better in small trials, unchanged in the main result of the US trial in trials
A longer Alzheimer's test of memory and language. A lower score means better thinking, so a gain is shown as a score drop.
Mixed findingsResults and what it means
Why it was measured
It is the main thinking test used in Alzheimer's drug trials.
Statistical vs. clinical meaning
The best-run US trial did not confirm the small-trial gains in its main analysis.
Safety implication
Not described in the abstract.
| Study | Result | People | Product |
|---|---|---|---|
| 4 | WMD 1.91 (1.27 to 2.55) at 6 weeks; 2.51 (1.74 to 3.28) at 12 weeks | Alzheimer's disease | Huperzine A |
| 5 | Lower study amount: no change at 16 weeks. Higher study amount: 2.27 vs -0.29 points at 11 weeks, 1.92 vs 0.34 at 16 weeks (p = 0.07) | 210 people with mild to moderate Alzheimer's disease | Huperzine A capsules |
Activities of daily living (ADL) score
Better in poor-quality trials; not significant in the US trial in trials
A score of how well a person manages everyday tasks. Direction depends on the scale used.
Low certaintyResults and what it means
Why it was measured
Everyday function matters more to families than test scores alone.
Statistical vs. clinical meaning
Evidence is weak and no quality-of-life data exist.
Safety implication
Not described.
Memory quotient (MQ)
Higher in small trials (very weak evidence) in trials
A score from a memory test scaled like an IQ score; higher is better.
Not enough evidenceResults and what it means
Why it was measured
Used in trials in students and in mild cognitive impairment.
Statistical vs. clinical meaning
Small, old and low-quality sources; not confirmed.
Safety implication
Not described.
Schizophrenia symptom total (PANSS or BPRS)
Lower with huperzine A in pooled trials (low certainty) in trials
A rating scale of schizophrenia symptoms. A lower score means fewer symptoms.
Low certaintyResults and what it means
Why it was measured
To see whether adding huperzine A to medicine changed overall symptoms.
Statistical vs. clinical meaning
All trials were in China and the authors ask for better trials.
Safety implication
Side effects and dropouts were similar between groups.
| Study | Result | People | Product |
|---|---|---|---|
| 12 | SMD -0.77 (95% CI -1.27 to -0.27) | Schizophrenia spectrum disorders, 8 trials using PANSS or BPRS | Huperzine A added to antipsychotics |
Wechsler Memory Scale-Revised memory quotient
Higher with huperzine A (low certainty) in trials
A standard memory test score; higher is better.
Low certaintyResults and what it means
Why it was measured
A measure of memory used in the schizophrenia trials.
Statistical vs. clinical meaning
A test score, not proof of day-to-day benefit.
Safety implication
Not described.
| Study | Result | People | Product |
|---|---|---|---|
| 12 | WMD 10.59 (95% CI 5.65 to 15.53) | Schizophrenia spectrum disorders, trials in China | Huperzine A added to antipsychotics |
Time the compound stays in the body (half-life)
About 12 hours in healthy men in trials
How long it takes the blood level to fall by half after a single dose.
Moderate certaintyResults and what it means
Why it was measured
To understand how long its action lasts and how it builds up with repeat use.
Statistical vs. clinical meaning
A measurement in healthy men; not a benefit.
Safety implication
No adverse events were reported in this single-dose study.
| Study | Result | People | Product |
|---|---|---|---|
| 8 | About 12.1 hours (reference formulation); peak 1.55 ng/mL | Healthy Chinese male volunteers, single dose | Three oral huperzine A formulations |
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 4
- It acts on the same enzyme as prescription dementia medicines. Huperzine A blocks acetylcholinesterase. Galantamine, a prescription Alzheimer's medicine, is in the same class (MedlinePlus). No study of huperzine A taken together with a dementia medicine was found, so nobody can say that combining them is safe. MedlinePlus warns, for galantamine, about slow heartbeat, fainting, seizures and breathing problems, and about interactions with common medicines. Those warnings are about the prescription drug. They may or may not apply to huperzine A, and no source read says. Ask a prescriber or pharmacist before combining, and never stop or swap a prescribed medicine on your own. Drug class reasoning and authoritative guidance (no huperzine A interaction study found) 13 4 8
- Labels often do not match what is in the bottle. A laboratory study of 22 supplements that listed huperzine A found that 16 (73%) had at least one labelled ingredient it could not detect, and 16 (73%) contained compounds not on the label. Nine (41%) listed ingredients that do not meet FDA rules for a supplement ingredient. Stimulants of concern were found in some. Only 2 of 22 had huperzine A within 10% of the declared amount, and the amounts ranged from too little to measure up to 267.1 micrograms per serving. So a product may have much less, or other ingredients, than you expect. Laboratory product analysis 1 2 14
- Supplements are not approved for safety before sale. NCCIH says the FDA is not authorised to review dietary supplements for safety and effectiveness before they are sold, and can act only after a product is on the market. Companies are responsible for safe, truthful products. A 2023 review adds that older adults' supplements should be known to their doctors because of side effects and interactions with prescribed medicines. Authoritative guidance and review 14 2
- Short trials found mild effects only, which is not long-term proof. Trials in people with Alzheimer's disease, in schizophrenia and in healthy volunteers reported mild side effects and no severe ones. These trials were small and short (single dose up to about 16 weeks). Long-term safety, and safety in people with heart-rhythm, breathing or stomach problems, was not shown in the sources read. Meta analysis and randomised trials 4 9 12 8
Side effects 3
| Effect | How often | Severity and recovery | Evidence |
|---|---|---|---|
| Mild side effects in trials (type not detailed) The abstracts do not list which side effects occurred, so none are named here. | Cochrane 2008: no significant difference from placebo. Schizophrenia review: similar to comparison. Frequencies are not in the abstracts. | Described as mild; no severe events reported in the reviews Not described | Meta-analysis 4 9 12 |
| No adverse events after a single dose in healthy men One dose in healthy Chinese men; does not cover repeat use, older adults or other people. | No adverse events reported | Not applicable Not applicable | Crossover trial 8 |
| Effects typical of acetylcholinesterase-blocking medicines (nausea, vomiting, diarrhoea, dizziness, slow heartbeat) Included so readers know what to watch for. It is not evidence that huperzine A causes these. | Listed on the MedlinePlus galantamine page for that prescription medicine. Not shown for huperzine A in the sources read. | Galantamine page: some effects can be serious (slowed heartbeat, fainting, seizures) Not described | Drug class extrapolation (not proven for huperzine A) 13 |
Liver
No liver injury from huperzine A was found in the sources read. The liver-safety reference LiverTox was tried but showed a browser check and was not read, so this is a gap, not a finding of safety.
How often. No frequency was found.
Monitoring. No agency monitoring advice was found.
This is a safety connection. It is not evidence that Huperzine A and other herbal cholinesterase products supports liver health.
Medicines and supplements 5
| With | Why it matters | Importance | Evidence | What to do |
|---|---|---|---|---|
| Prescription dementia medicines (for example galantamine; the same class) prescription | Both block acetylcholinesterase (MedlinePlus lists galantamine as an acetylcholinesterase inhibitor). | No study of the combination was found. Effects could add together, but no source read shows what happens. | Drug class reasoning Not enough evidence 13 4 | Ask a prescriber or pharmacist before combining. |
| Medicines that block acetylcholine or are listed with galantamine (for example diphenhydramine, meclizine, loperamide) nonprescription | The MedlinePlus galantamine page lists these as nonprescription products that may interact with galantamine. Whether they interact with huperzine A was not found. | Unknown for huperzine A. | Drug class extrapolation Not enough evidence 13 | Tell your pharmacist about every product you take, including herbal ones. |
| Antipsychotic medicines prescription | Huperzine A was added to antipsychotics in 12 trials without more side effects than comparison (abstract). | Side effects and dropouts were similar. Details of the combinations were not in the abstract. | Meta-analysis Low certainty 12 | Do not add a supplement to psychiatric medicine without the prescriber's agreement. |
| Other ingredients in brain blends (stimulants, curcumin and others) supplement | In the product analysis, undeclared stimulants were found in some products listing huperzine A. | Unlisted stimulants could add to the effects of other medicines or supplements. | Laboratory product analysis Low certainty 1 | Check labels and ask a pharmacist. |
| Surgery and anaesthesia procedure | NCCIH says some supplements can affect surgery and anaesthesia. It does not name huperzine A. | Not specific to huperzine A in the sources read. | Authoritative guidance (general) Not enough evidence 14 | Tell your surgeon and anaesthetist about every supplement before a procedure. |
Who should check first 5
| Situation | Advice | Evidence |
|---|---|---|
| Anyone taking a dementia medicine such as galantamine | No study of the combination was found. Ask a prescriber or pharmacist; do not stop a prescribed medicine on your own. | Drug class reasoning 13 |
| Pregnancy and breastfeeding | No data on huperzine A in pregnancy or breastfeeding were found. NCCIH says many dietary supplements have not been tested in pregnant women or nursing mothers. Ask a doctor first. | Gap and authoritative guidance (general) 14 |
| Children and teenagers | NCCIH says many supplements have not been tested in children. One small 1999 trial gave huperzine A to school students for 4 weeks, but the abstract does not report side effects, so it does not show safety. Ask a doctor first. | Gap, authoritative guidance (general) and a small trial 14 6 |
| Heart-rhythm, breathing, seizure, stomach or kidney problems | The galantamine page lists slow or irregular heartbeat, asthma and lung disease, seizures, ulcers and kidney or liver disease as things to tell a doctor about. No source read tested huperzine A in these groups. Ask a doctor first. | Drug class extrapolation 13 |
| Memory change in an older adult | New or worsening memory problems need a medical check. A supplement should not replace diagnosis or treatment. | Authoritative guidance (general) 14 |
Overdose, product quality and regulators
Summary. No toxicity data for huperzine A taken as a supplement were found in the sources read. Prescription medicines that block the same enzyme can cause serious effects in overdose.
Animal. Not reviewed.
Overdose response. The galantamine page lists muscle weakness or twitching, nausea, vomiting, stomach cramps, drooling and watery eyes among overdose signs of that medicine. For any overdose or poisoning, call poison control (1-800-222-1222 in the US) or emergency services.
Genotoxicity. Not researched.
Toxic or hazardous parts. Not assessed.
Product quality is a real concern. A laboratory study found most products that listed huperzine A did not match their labels.
Label accuracy. 16 of 22 products (73%) had a labelled ingredient not detected; only 2 of 22 had huperzine A within 10% of the declared amount. 1
Unlisted ingredients. Compounds not on the label were found in 16 products (73%), including stimulants such as higenamine, vinpocetine, noopept and hordenine. Nine products (41%) listed ingredients that do not meet FDA rules for a supplement ingredient. 1
Regulation. NCCIH says the FDA can act on a supplement only after it is on the market and cannot test every product. 14
| Body | Action | Date |
|---|---|---|
| NCCIH (US National Institutes of Health) (United States) | Says the FDA is not authorised to review dietary supplements for safety and effectiveness before marketing, and can act only after a product is on the market. Says many supplements have not been tested in pregnant women, nursing mothers or children, and that some can interact with medicines or affect surgery. It does not mention huperzine A. source | 2026-10-26 |
| MedlinePlus (US National Library of Medicine) (United States) | Says galantamine is in a class of medicines called acetylcholinesterase inhibitors and lists precautions, interactions and overdose signs for that medicine. It does not mention huperzine A. source | 2026-08-15 |
When to get medical help
- Someone has taken too much of any product, or has muscle twitching, drooling, vomiting and stomach cramps: call poison control or emergency services.
- Fainting, a very slow heartbeat, chest pain or trouble breathing after starting a supplement that acts on acetylcholine: get urgent medical help.
- A seizure: call emergency services.
- Black or bloody stools, or vomiting blood: get urgent medical help.
- New or worsening confusion, memory loss or personality change in a person: see a doctor; do not rely on a supplement.
Stop using the product 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 huperzine A?
Does huperzine A treat Alzheimer's disease?
Does huperzine A help memory in healthy people?
Is it the same as a dementia medicine?
Can I take it with dementia medicines?
No study of the combination was found, so nobody can say it is safe. Ask a prescriber or pharmacist, and do not stop or swap a prescribed medicine on your own.
What side effects did trials report?
Can I trust the label on a huperzine A supplement?
Not always. In a laboratory study of 22 products, 73% had a labelled ingredient not detected, 73% had unlisted compounds, and only 2 were within 10% of the declared huperzine A amount.
Is it safe in pregnancy, breastfeeding or for children?
No safety data were found. NCCIH says many supplements have not been tested in pregnant women, nursing mothers or children. Ask a doctor first.
Does it help with schizophrenia or brain injury?
Do other herbs act as natural cholinesterase blockers?
Some labels say so for other plant extracts. No human trial for such a claim was read, so none is made here.
Should I tell my doctor if I use it?
Who should see a doctor first?
Anyone with new or worsening memory problems needs a medical check. A supplement should not replace diagnosis or care.
Explore by health goal
Editorial transparency
- Written by
- AlternativeMed editorial team. Research compiled with AI assistance, then checked against the sources listed.
- Medical review
- None. This page has not been reviewed by a physician or pharmacist.
- First published
- 2026-10-26
- Last substantive update
- 2026-10-26
- How we research
- We started from our existing huperzine A summary, read the MedlinePlus galantamine page and the NCCIH page on using supplements wisely, and re-read PubMed abstracts for reviews, trials and a laboratory product analysis. Only abstracts were read for studies. A liver-safety page was blocked by a browser check and is marked unread.
- 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. Trials may have funding links not stated in abstracts.
Sources 14
Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.
- Crawford C, Wang YH, Avula B, Bae JY, Khan IA, Deuster PA. The scoop on brain health dietary supplement products containing huperzine A.. Clin Toxicol (Phila). 2020. PMID 31990212. DOI 10.1080/15563650.2020.1713337. (abstract)
- Hersant H, He S, Maliha P, Grossberg G. Over the Counter Supplements for Memory: A Review of Available Evidence.. CNS Drugs. 2023. PMID 37603263. DOI 10.1007/s40263-023-01031-6. (abstract)
- Huang P, Li B, Guo YH, Feng S, Hu J, Liu QQ. [Efficacy and safety of huperzine A in treating patients with mild cognitive impairment: a systematic review and Meta-analysis].. Zhongguo Zhong Yao Za Zhi. 2019. PMID 30989926. DOI 10.19540/j.cnki.cjcmm.20180925.008. (abstract)
- Li J, Wu HM, Zhou RL, Liu GJ, Dong BR. Huperzine A for Alzheimer's disease.. Cochrane Database Syst Rev. 2008. PMID 18425924. DOI 10.1002/14651858.CD005592.pub2. (abstract)
- Rafii MS, Walsh S, Little JT, Behan K, Reynolds B, Ward C 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, Guo HM, Cao WQ. Huperzine-A capsules enhance memory and learning performance in 34 pairs of matched adolescent students.. Zhongguo Yao Li Xue Bao. 1999. PMID 10678121. (abstract)
- Tabira T, Kawamura N. A Study of a Supplement Containing Huperzine A and Curcumin in Dementia Patients and Individuals with Mild Cognitive Impairment.. J Alzheimers Dis. 2018. PMID 29614668. DOI 10.3233/JAD-171154. (abstract)
- Wu SL, Gan J, Rao J, He SJ, Zhu WW, Zhao Y 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 Technolog Med Sci. 2017. PMID 29058298. DOI 10.1007/s11596-017-1807-8. (abstract)
- Yang G, Wang Y, Tian J, Liu JP. 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, Yang M, Wu HM, Wu T. 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, Goldstein R, Boudreau N, Monge I 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)
- Zheng W, Xiang YQ, Li XB, Ungvari GS, Chiu HF, Sun F 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)
- . MedlinePlus Drug Information: Galantamine (page last revised 2026-08-15). . . (full-text)
- . NCCIH: Using Dietary Supplements Wisely. . . (full-text)
