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Huperzine A

Scientific Name(s): Huperzia serrata (Thunb.) Trev., Lycopodium serratum (Thunb.).
Common Name(s): Brainmax, Chien Tseng Ta, Club moss, Jin Bu Buan, Memorzine, Neuroflow, Qian Ceng Ta, She Zu Cao, Shi Song

Medically reviewed by Last updated on Jul 14, 2022.

Clinical Overview


Historically, club moss has been used for the treatment of bruises, strains, swelling, rheumatism, and colds, to relax muscles and tendons, and to improve blood circulation. Because of its anticholinesterase activity, huperzine A, a constituent of the whole plant, has been studied for potential use in treating Alzheimer disease and other CNS disorders; however, there is still insufficient evidence to support its routine use.


Huperzine A has been studied at oral dosages of 0.2 to 0.4 mg/day for Alzheimer disease.


Contraindications have not been identified.


Information regarding safety and efficacy in pregnancy and lactation is lacking.


None well documented.

Adverse Reactions

In clinical trials, cholinergic adverse reactions have been noted, including hyperactivity, nasal obstruction, nausea, vomiting, diarrhea, insomnia, anxiety, dizziness, thirst, and constipation. One trial reported abnormalities in electrocardiogram (ECG) patterns (cardiac ischemia and arrhythmia). Drug-induced liver injury has been reported.


Symptoms of acute toxicity are similar to those of other cholinergic inhibitors and include muscular tremor, drooling, tears, increased bronchial secretions, and incontinence. No mutagenicity or teratogenicity were found in rodent studies.

Scientific Family

  • Lycopodiaceae (club moss)


Huperzine A is isolated from the club moss Huperzia serrata, also known as Lycopodium serratum Thunb. Distributed worldwide, club moss is found in subtropical zones of the United States and in southern China. It has been extensively cultivated and may be threatened in the wild in China.

Club mosses are primitive, vascular plants that differ from true mosses by having specialized fluid-conducting tissues, but, like mosses, they reproduce by means of spores, which are either clustered into small cones or born in the axils of the small, scale-like leaves. Plants older than 15 years may only grow to 10 cm in height. Some species of Lycopodium are called ground pine or creeping cedar, especially those that resemble miniature hemlocks, with flattened fan-shaped branches often used for Christmas decorations.Ma 2006, USDA 2009 A synonym is Lycopodium serratum Thunb.


The use of club moss can be traced back to the Chinese pharmacopoeias of the Tang dynasty as Shi Song, used for the treatment of rheumatism and colds, to relax muscles and tendons, and to improve blood circulation. As Qian Ceng Ta, it has been used for the treatment of bruises, strains, and swelling, and, more recently, for organophosphate poisoning, myasthenia gravis, and schizophrenia. The study of the chemistry and pharmacology of the plant and its alkaloids gained momentum in the 1980s from Chinese scientists.Ma 2007, Tang 1999, Wang 2006, Zhu 2004


A review of the chemical composition of club moss has been published. The plant contains mainly alkaloids, triterpenes, flavones, and phenolic acids. Four major structural classes of Lycopodium alkaloids have been described, including lycopodine, lycodine (to which huperzine A belongs), fawcettimines, and others.Ma 2007 The yield of huperzine A from H. serrata is reported to be approximately 0.1% on a dry weight basis.Yu 1993

Huperzine analogs have been synthesized to improve binding and pharmacological actions. More detailed analyses of huperzine B and the enantiomer of natural huperzine A have also been made.Carlier 2000, Darrouzain 2005, Dvir 2002, Foricher 2000, Jiang 2003, Kozikowski 1991, McKinney 1991, Rajendran 2002, Wong 2003

Uses and Pharmacology

Huperzine A is approved for use as a drug for the treatment of Alzheimer disease in China; however, it is regulated as an herbal supplement in the United States.Alzforum 2009 Several firms (Solgar, Pharmavite, GNC, Kingchem, and NOW Foods) filed the required premarket notifications with the Food and Drug Administration between 1997 and 2000 for huperzine A products manufactured in China from natural sources.FDA 1997

Alzheimer disease

A Cochrane review of the effect of huperzine A in Alzheimer disease has been published, as well as other reviews.Desilets 2009, Kelley 2008, Li 2008 All reviews note the lack of quality long-term clinical trials to support definitive statements about a place in therapy for huperzine A, despite the numerous clinical studies being undertaken.Desilets 2009, Li 2008, Little 2008

Animal data

Animal and in vitro experiments have been conducted, and the mechanism of action for huperzine appears to be a combination of anticholinesterase activity and antiglutamate, antioxidant, and neuroprotective effects.Jiang 2003, Kelley 2008, Li 2008, Little 2008, Patil 2003, Peng 2006, Tang 2005, Wang 2006, Zhang 2008 Huperzine A crosses the blood-brain barrier more effectively than tacrine or donepezil and acts with greater potency than tacrine, physostigmine, or galanthamine.Lallement 2002, Little 2008 Huperzine A is selective for brain acetyl cholinesterase over plasma butyryl cholinesterase, which may account for its reported lower adverse effect profile in clinical studies.Cheng 1998, Little 2008

Clinical data

Based on limited data, some beneficial effects are attributed to huperzine A in Alzheimer disease, including an increase in general cognitive function, global clinical status, behavioral disturbances, and physical performance. Not all measurement scales found positive effects for huperzine A over placebo.Li 2008 The results of a US multicenter, phase 2 clinical trial (now closed), in which huperzine A was evaluated at 2 different doses versus placebo, are awaited.Aisen 2004, Little 2008 A systematic review and meta-analysis evaluating the effect of huperzine A for treatment of Alzheimer disease identified 20 randomized clinical trials that included over 1,800 participants; the quality of most trials had a high risk of bias. Regardless of disease course, disease severity, treatment preparation, dose, or duration, results showed favorable and sometimes significant effects on cognitive function and favorable effects on activities of daily living for huperzine A compared with placebo.Yang 2013 The American Psychiatric Association (APA) guideline watch for the treatment of patients with Alzheimer disease and other dementias (2014) did not find enough definitive new evidence to change the 2007 guideline recommendations for alternative agents, including huperizine A.Rabins 2014

Other CNS effects


High quality clinical trials are lacking; however, 1 review of 4 clinical trials found improvement against memory, dementia, and Alzheimer scales,Diamond 2003 while a Cochrane review found only 1 clinical trial meeting inclusion criteria in which no difference compared with placebo was found for vascular dementia.Hao 2009


Anticonvulsant activity of huperzine A has been demonstrated in mice, and a pilot clinical study is being undertaken.Bialer 2007

Organophosphate antidote

Huperzine A's potent inhibition of cholinesterase has also made it a candidate for prevention of poisoning by the nerve agent soman and other organophosphates. In contrast to pyridostigmine, huperzine A crosses the blood-brain barrier and, therefore, may be effective in preventing seizures and other neuropathology caused by soman.Grunwald 1994, Wang 2006 Animal experiments have demonstrated activity against soman-induced seizures and mortality; however, clinical studies are lacking.Bajgar 2009, Eckert 2007, Gordon 2005, Grunwald 1994, Jiang 2003, Tonduli 2001

Parkinson disease

Protective effects have been demonstrated in mice models, but clinical trials are lacking.Chen 2007


A small (N = 19), open-label clinical study found improved cognitive effects for huperzine A over 12 weeks.Zhang 2007 Clinical trials on the use of huperzine in schizophrenia in the United States are being prepared for recruitment.Padala 2009, Woods 2009


Huperzine A in pure form has been studied at oral dosages of 0.2 to 0.4 mg/day for Alzheimer disease. It has also been administered intramuscularly at 0.06 to 0.4 mg/day in dementia studies.Desilets 2009, Diamond 2003, Jiang 2003, Kelley 2008, Li 2008, Little 2008

In an open-label study among patients with schizophrenia, 0.3 mg/day for 12 weeks was used.Zhang 2007

The pharmacokinetics of huperzine A have been studied in healthy adult volunteers. A half-life of 288 minutes was reported, comparable with that of donepezil, while no tolerance was noted with multiple dosing.Little 2008 Transdermal patches have been tested in beagles.Wang 2006

Pregnancy / Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking.


Concomitant use of huperzine A with cholinesterase inhibitors could lead to potentiation of adverse reactions, although case reports are lacking.Kelley 2008

In vitro studies suggest potentiation of huperzine A by the green tea polyphenol epigallocatechin-3-gallate.Zhang 2009

Adverse Reactions

In clinical trials, cholinergic side effects were noted, including hyperactivity, nasal obstruction, nausea, vomiting, diarrhea, insomnia, anxiety, dizziness, thirst, and constipation. One trial reported abnormalities in ECG patterns (cardiac ischemia and arrhythmia).Li 2008

The European Association for the Study of the Liver (EASL) clinical practice guideline for drug-induced liver injury (2019) recommends physicians consider herbal and dietary supplements as potential causative agents associated with liver injury (Level 4; Grade C), including Huperzine A (Lycopodium serratum; Jin Bu Huan).EASL 2019


Symptoms of acute toxicity are similar to those of other cholinergic inhibitors and include muscular tremor, drooling, tears, increased bronchial secretions, and incontinence.Little 2008

The acute oral median lethal dose of huperzine A in rats has been reported as 4.6 mg/kg and as an intravenous dose of 0.63 mg.Ma 2007 One toxicological study reported increases in serum aminotransferases.Wang 2006 No pathological changes were found in histological studies of the liver, kidney, heart, lungs, or brain after 180 days of administration, and no mutagenicity or teratogenicity were found in rodent studies.Ma 2007

Index Terms

  • Lycopodium serratum Thunb.
  • Club Moss
  • Creeping Cedar
  • Ground Pine



This information relates to an herbal, vitamin, mineral or other dietary supplement. This product has not been reviewed by the FDA to determine whether it is safe or effective and is not subject to the quality standards and safety information collection standards that are applicable to most prescription drugs. This information should not be used to decide whether or not to take this product. This information does not endorse this product as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this product. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this product. This information is not specific medical advice and does not replace information you receive from your health care provider. You should talk with your health care provider for complete information about the risks and benefits of using this product.

This product may adversely interact with certain health and medical conditions, other prescription and over-the-counter drugs, foods, or other dietary supplements. This product may be unsafe when used before surgery or other medical procedures. It is important to fully inform your doctor about the herbal, vitamins, mineral or any other supplements you are taking before any kind of surgery or medical procedure. With the exception of certain products that are generally recognized as safe in normal quantities, including use of folic acid and prenatal vitamins during pregnancy, this product has not been sufficiently studied to determine whether it is safe to use during pregnancy or nursing or by persons younger than 2 years of age.

More about huperzine a

Related treatment guides

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