Huperzia and Huperzine A (Huperzia serrata): Uses, Evidence and Safety

Safety first: medicines that work the same way. Huperzine A blocks the enzyme acetylcholinesterase. [1] Memorial Sloan Kettering Cancer Center says huperzine works by the same mechanism as the acetylcholinesterase inhibitor drugs donepezil, galantamine and rivastigmine and may increase the risk of adverse effects if combined with them, and warns it may lower heart rate with calcium channel blockers or beta blockers. [2] If you or someone you care for takes any of these medicines, talk to the prescriber or pharmacist before adding huperzine A. See how interactions work.

Overview

Huperzine A is a purified alkaloid from the club moss Huperzia serrata. Memorial Sloan Kettering says it is marketed as a dietary supplement to improve brain function, and that studies on it are limited and mixed. [2] This page covers the supplement and the plant it comes from. A shorter tradition-focused guide is at Huperzia serrata and huperzine A in Chinese folk medicine. For other memory products see herbs for memory, focus and brain health.

Names, plant part and name traps

The accepted name is Huperzia serrata (Thunb.) Trevis., in the club moss family (Lycopodiaceae). [3] It is described as a type of fir moss, and an older name, Lycopodium serratum, appears in some sources. [2] Research and supplements concern huperzine A, an extract; most studies of the plant are in fact based on huperzine A. [2] We give no identification or foraging advice. For wild plants use expert local botanists, and for any plant eaten by mistake see plant and mushroom poisoning and call Poison Help at 1-800-222-1222 (US).

Traditional use (not proof)

Memorial Sloan Kettering says H. serrata is used as a component in traditional Chinese herbal formulas for blood circulation and to relieve pain. [2] The same source says huperzine A has been used as a treatment for Alzheimer's disease and vascular dementia in Asia. [2] Long-standing use is not trial evidence.

What research shows

All results are for huperzine A taken by mouth, not the whole plant.

"Improvement on a score" is not the same as feeling or functioning better. The US trial's authors said the primary analysis did not show a cognitive benefit at the lower amount. [5] Anyone with memory loss needs a clinical assessment; see mild cognitive impairment and dementia and memory changes and when to get help.

Forms and why the form matters

Trials used huperzine A, an extract. Plant powder or tea from Huperzia is a different product with no human research found in our sources. Supplement amounts also vary: in a laboratory analysis of 22 products listing huperzine A, only two contained an amount within 10% of the label. [7]

Safety

• Medicines. Huperzine works by the same mechanism as donepezil, galantamine and rivastigmine, and may increase the risk of adverse effects. [2] It may lower heart rate with calcium channel blockers or beta blockers. [2] It may cause symptoms of Parkinson's disease with dopamine D2 receptor blockers. [2] Laboratory studies indicate it induces the liver enzyme CYP3A4, with clinical relevance not yet determined. [2] Never stop or change a prescribed medicine on your own; ask the prescriber or pharmacist. See herbs and people taking many medicines.
• Side effects. Listed effects include nausea, thirst, abdominal pain, dizziness, vomiting, constipation, diarrhea and insomnia, and slow heart beat. [2] In the US trial, no serious adverse event was considered possibly related to the study medicine, and it was generally well tolerated up to 400 micrograms twice daily for 24 weeks. [5]
• Pregnancy, breastfeeding and children. Not described in the sources we read. Lack of information is not proof of safety; see pregnancy and breastfeeding.
• Liver, kidney, bleeding, surgery, allergy. Not described in the sources we read. Tell the surgical team about every supplement; see supplements before surgery.
• Older adults. Not described in the sources we read; see older adults for general medicine-list cautions.

Quality

In that 22-product analysis, 73% had at least one labeled ingredient not detected and 73% contained compounds not on the label, including stimulants. [7] Nine products listed ingredients that did not meet FDA rules for a dietary supplement ingredient. [7] See product quality and contamination and quality testing and certifications.

Official statements

Proper evidence not found: we did not find a readable regulator statement on huperzine A in this session (searches of FDA, NCCIH and MedlinePlus pages returned nothing usable). The medicines and safety points above come from a cancer-center clinical reference, last updated 2022. [2]