Cholinesterase Inhibitor
Huperzine A
A potent compound that enhances acetylcholine levels by preventing its breakdown.
KÖGN Health grades Huperzine A as A+ (Strong evidence) and rates it 4.2 out of 5.
Last reviewed · June 2026
Primary effects
- Improved memory
- Enhanced learning
- Increased focus
How it works
Inhibits acetylcholinesterase, increasing acetylcholine availability for memory and learning.
Overview
Huperzine A is a highly potent nootropic often used for memory enhancement. Due to its long half-life and strength, it is typically used in cycles rather than daily to avoid overstimulation. It is frequently included in advanced stacks targeting memory and cognitive performance.
The evidence
Huperzine A is a plant alkaloid that inhibits acetylcholinesterase, raising levels of the learning-and-memory neurotransmitter acetylcholine — the same mechanism as some Alzheimer's drugs. Meta-analyses of trials in Alzheimer's report improved cognitive scores, but reviewers caution that most trials are small and of low methodological quality, and a higher-quality phase II trial found no benefit. Evidence in healthy people is minimal.
How to dose it
Studied at roughly 200–400 micrograms per day (note: micrograms, not milligrams) — it is potent at very small doses.
When to take it
Both — it acts on acetylcholine acutely, with trials run over weeks.
Safety & side effects
Usually well tolerated at these doses; cholinergic effects such as nausea, sweating, or a slowed heart rate can occur, more so at higher doses.
Who should avoid it
Because it is a cholinesterase inhibitor, do not combine it with prescription drugs of the same class (donepezil, rivastigmine, galantamine) or with anticholinergics without medical advice. Use caution with epilepsy, asthma, slow heart rhythms, or before surgery. Not for use in pregnancy.
References
Related ingredients
Graded entries that target the same cognitive goals.
Categories
Draft — the dose, safety and evidence notes on this entry were prepared from the published literature and are pending editorial and clinical review.
Educational information, not medical advice. The evidence grade is KÖGN’s editorial assessment of published research, not a health claim. Speak to a qualified clinician before changing what you take.