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Ingredients / Huperzine A
Limited evidence overall 12 articles · reviewed 2 Sep 2026

Huperzine A

Alkaloid from Huperzia serrata

A cholinesterase inhibitor sold as a nootropic. It is pharmacologically active, which is precisely why casual daily use in healthy people is a bad idea.

What the evidence supports

Limited Cognition in healthy adults Almost no controlled data. The nootropic use case is extrapolated from dementia trials.
Moderate Alzheimer disease Chinese trials report cognitive-scale improvements, but methods reporting is often incomplete and independent replication is limited.
Limited Memory in adolescents One frequently cited small trial, never replicated.
Limited Long-term safety No trial has followed healthy users beyond a few months.
Dose used in trials
50–200 mcg

per day in dementia trials. Many consumer blends list it without disclosing the microgram amount.

Safety
Pharmacologically active

Cholinergic effects — nausea, sweating, slowed heart rate, vivid dreams. Not a benign botanical.

Ask a doctor first if
Four cases

Any cholinesterase-inhibitor medication, asthma, bradycardia or heart-rhythm disorders, or epilepsy.

The trials, individually

Open any one for sample size, funding and what it actually measured.

Cochrane review · 20 trials · Alzheimer
Reports benefit on cognitive scales but rates most included trials as poor quality, with inadequate randomisation and allocation-concealment reporting.
Rafii et al. · 210 adults · Alzheimer
A US trial at 200 and 400 mcg twice daily. The primary cognitive endpoint was not met; a secondary signal at the higher dose was not conclusive.
Sun et al. · 68 students · memory
Four weeks, adolescents. Memory-test scores improved. Widely cited in marketing, never replicated, and not applicable to adults dosing daily for years.

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