Huperzine A
Also known as: Huperzia serrata extract, toothed clubmoss extract, Hup A, selagine
Huperzine A is an alkaloid from the club moss Huperzia serrata that reversibly inhibits acetylcholinesterase, raising acetylcholine levels in the brain. Meta-analyses of Chinese trials in cognitive impairment report benefits on memory scales, although trial quality is generally low. In supplements it appears at 50–200 mcg in nootropic and pre-workout stacks. Because it is potent and long-acting, it is typically cycled rather than used daily long-term, and it must be diluted on a carrier for accurate dosing.
Research summary
Reversible, selective acetylcholinesterase inhibitor with a plasma half-life long enough to accumulate with daily dosing.
Dosage
Daily amounts, of compound.
| Lowest studied | Typical range | Highest studied | Upper limit |
|---|---|---|---|
| 50 mcg | 50–200 mcg | — | — |
50–200 mcg once daily, often cycled (for example, 5 days on, 2 off, or a few weeks on then off) because acetylcholinesterase inhibition accumulates. Cognitive-impairment trials used higher daily amounts under medical supervision. Not intended for continuous long-term use. Cholinergic side effects such as nausea or vivid dreams signal the dose is too high.
Standardization: Huperzia serrata extract standardized to 1% huperzine A (also 0.5% and 99% pure)
Source material: whole-herb extract of Huperzia serrata
As supplied: 1% huperzine A dilution: 0.1 mg of extract per 1 mcg huperzine A (200 mcg ≈ 20 mg extract).
Format suitability
- Capsule
- Powder
- Tablet
- Softgel
- Gummy
- Liquid
Microgram dose; always use a diluted grade and ensure blend uniformity. Not suited to gummies or liquids for dose-accuracy reasons.
Formulation notes
Additive with cholinesterase-inhibitor drugs and cholinergic supplements; caution with anticholinergics, beta-blockers, and in seizure or heart-rhythm conditions.
- Notable drug interactions
Sources
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