Huperzine A

Huperzia serrata · Selagine

Snapshot

Indications	Contraindications
Alzheimer's disease cognition^{1, 2} Vascular dementia^{3, 4} Daily function in dementia⁵ Subjective memory complaints⁶	Pregnancy or breastfeeding⁷ Under age 18⁷ Seizure disorder⁶ Cholinesterase inhibitor co-use⁶

Huperzine A is an alkaloid extracted from the firmoss Huperzia serrata that reversibly inhibits acetylcholinesterase^{2, 8}. It is taken to support memory and cognition in Alzheimer's disease, where a meta-analysis of four randomized trials found improved cognitive scores and daily living¹.

In Alzheimer's disease, a Cochrane meta-analysis of small, mostly low-quality trials found better cognition and daily function, but judged the evidence inadequate to recommend use². In vascular dementia, a network meta-analysis ranked it among the most effective options, while a Cochrane review of one small trial found no convincing benefit. In exercise-trained adults, a 2021 crossover trial found no improvement in cognitive function⁹. A 2023 review of nootropic supplements listed huperzine A among ingredients unauthorized as food or supplement ingredients by the European Commission¹⁰. Products are sold as tablets and capsules, and an analysis of products listing it found most did not match the declared amount; see Form comparison.

The main caution is additive cholinergic activity: the Alzheimer's Drug Discovery Foundation notes it behaves like donepezil and may worsen that medication's side effects⁶. United States (US) product labels ask users with heart problems or on acetylcholinesterase inhibitors to consult a physician first⁷.

Last updated October 16, 2026. Read how we make monographs.

In the full monograph

61 sources, 43 studies

When to useThe situations practitioners use it for, each with the reason and the study behind it.
SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
InteractionsThe medicines and supplements it interacts with, the effect of each, and what labeling says to watch.
Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
How it worksWhat it is and how it works in the body, in plain terms.
Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.

Snapshot

In the full monograph

Sources