Huperzine A
Summary
Huperzine A is a club-moss alkaloid that acts like an Alzheimer drug by blocking acetylcholinesterase. Chinese trials suggest better cognitive scores in Alzheimer disease (20 RCTs, mostly high risk of bias). The best-designed US trial (210 people) found no benefit at 200 mcg twice daily. Drug-like effects call for care with other cholinergic medicines.
Key facts
- A Huperzia serrata alkaloid that inhibits acetylcholinesterase[1]
- 20 RCTs (1,823 people) favour it in Alzheimer disease, but most had high risk of bias[2]
- No ADAS-Cog benefit at 200 mcg twice daily over 16 weeks (210 people)[1]
- 200–400 mcg twice daily in the US phase II trial[1]
- 3 graded human outcomes on this page
- October 11, 2026
How it works
EstablishedHuperzine A reversibly inhibits acetylcholinesterase, raising acetylcholine in synapses, the same target as donepezil and related Alzheimer drugs.[1][3]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Cognition and daily function in Alzheimer disease | Improved | Grade C | Meta-analysis · n = 1,823 · 2013 People with Alzheimer disease in 20 RCTs (mostly in China) Form: Huperzine A · Dose: Varied across trials · Duration: 8–16 weeks for most outcomes MMSE and other scores improved versus placebo, but most trials had high risk of bias. | 24086396 (opens PubMed)Source [2] |
| General cognitive function in Alzheimer disease | Improved | Grade C | Systematic review · n = 454 · 2008 People with Alzheimer disease in 6 trials Form: Huperzine A · Dose: Varied across trials · Duration: 6–12 weeks for ADAS-Cog MMSE improved by 2.81 points versus placebo, but only one trial was of adequate quality and size, so evidence was judged inadequate for a recommendation. | 18425924 (opens PubMed)Source [3] |
| ADAS-Cog in mild to moderate Alzheimer disease | No effect | No effect | RCT · n = 210 · 2011 Adults with mild to moderate Alzheimer disease (US multicentre) Form: Huperzine A · Dose: 200 mcg or 400 mcg twice daily · Duration: 16 weeks 200 mcg twice daily did not change ADAS-Cog versus placebo (primary outcome); 400 mcg twice daily showed a secondary-analysis signal. | 21502597 (opens PubMed)Source [1] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Huperzia serrata extract standardised to huperzine A (often 1%) | Varies | No head-to-head human absorption data in the sources cited here. | No obvious serious adverse events in the Cochrane review; labels list micrograms of huperzine A.[3] | Alzheimer trials |
Studied doses
Doses studied in human trials ranged from 200 mcg twice daily (0.4 mg/day) to 400 mcg twice daily (0.8 mg/day) for 16 weeks in the US phase II trial.[1]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
Medicines
- Acetylcholinesterase inhibitors and cholinergic drugsReviewHuperzine A acts on the same enzyme as donepezil, rivastigmine and galantamine, so effects could add up.[3]
Who should be careful
- People on Alzheimer drugs
- Same mechanism as prescription cholinesterase inhibitors.[3]
- Pregnancy and breastfeeding
- No safety data in the sources cited here.[2]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
Frequently asked questions
Does huperzine A improve memory?
Chinese trials in Alzheimer disease suggest it may, but the best-designed US trial found no benefit at the standard dose.[2][1]
Is huperzine A a drug?
It works like prescription Alzheimer drugs by blocking acetylcholinesterase, and it is sold as a supplement in the US.[1]
How is it dosed on labels?
In micrograms of huperzine A, often from an extract standardised to 1%.
Can it be combined with donepezil?
Both block the same enzyme; that combination belongs with a prescriber.[3]
Sources
- [1]A phase II trial of huperzine A in mild to moderate Alzheimer disease.. Neurology, 2011. RCT
- [2]Huperzine A for Alzheimer's disease: a systematic review and meta-analysis of randomized clinical trials.. PLoS One, 2013. meta-analysis
- [3]Huperzine A for Alzheimer's disease.. Cochrane Database Syst Rev, 2008. systematic-review
What changed
- First draft. Every PMID checked against NCBI E-utilities (title, journal and year taken from the PubMed record) and each evidence row written from its PubMed abstract.