Huperzine A, is a naturally occurring sesquiterpene alkaloid found in the plant extracts of the firmoss Huperzia serrata. The botanical has been used in China for centuries for the treatment of swelling, fever and blood disorders. In the West, it is used as an herbal supplement and is not approved for pharmaceutical use. Recently in clinical trials in China, it has demonstrated neuroprotective effects. Huperzine A has also attracted the attention of Western medical science. It is currently being investigated as a possible treatment for diseases characterized by neurodegeneration – particularly Alzheimer’s disease.It has been found to be an inhibitor of the enzyme acetylcholinesterase.This is the same mechanism of action of pharmaceutical drugs such as galantamine and donepezil used to treat Alzheimer's disease. Huperzine A is also a NMDA receptor antagonist which protects the brain against glutamate induced damage, and it increases nerve growth factor levels. Clinical trials in China have shown that huperzine A is comparably effective to the drugs currently on the market, and may even be a bit safer in terms of side effects.Currently, the National Institute on Aging is conducting a Phase II clinical trial to evaluate the safety and efficiency of huperzine A in the treatment of Alzheimer's disease in a randomized controlled trial of its effect on cognitive function.Recently, it has been investigated for its effectiveness against epilepsy in an initial 20-person clinical study by Harvard University neuroscientists examining its worth and side effects in those who are not satisfactorily treated by existing pharmaceuticals. Side effects may include breathing problems, tightness in the throat or chest, chest pain, skin hives, rash, itchy or swollen skin, upset stomach, diarrhea, vomiting, hyperactivity and insomnia.