Coptis (Coptis chinensis) is a low-growing, shrub-like perennial native to China that is a cousin to the North American herb, goldenseal. Also known as huang lian, mishmi bitter and Chinese gold thread, coptis is commonly used in Chinese medicine to treat conditions associated with excessive heat or dampness, such as insomnia. In fact, coptis is counted among the 50 fundamental Chinese herbs used to address dysfunction of the heart, lungs, gastrointestinal system and liver.

The medicinal part of the plant is the golden rhizome or root. Like goldenseal, coptis root contains berberine, a plant alkaloid extensively studied for its numerous pharmacological effects. For example, the antioxidant properties of berberine may help to enhance immune function. Berberine also demonstrates antimicrobial activity and effectively counters several pathogens, including Streptococcus, Staphylococcus, Candida and Salmonella, to name a few. According to the National Institutes of Health, berberine also checks various fungi and bacteria. In fact, one study sponsored by the agency showed that a single dose of berberine extract significantly improved diarrhea and other symptoms of Escherichia Coli.

Other studies indicate that coptis root lowers serum cholesterol, reducing the risk of atherosclerosis. In addition, a study published Cardiovascular Drug Review stated that berberine compounds may be useful in treating arrhythmias. In one study involving tuberculosis patients, three months of therapy with coptis root was credited with the cessation of fever, cough and spitting up blood. Meanwhile, Japanese scientists at Saitama Medical University have found that berberine extracts may slow the progression of Alzheimer’s disease. A few studies using animal models show that berberine reduces blood sugar.

Coptis root is generally safe and without significant side effects beyond mild stomach upset. However, people with Raynaud's disease may temporarily experience an increase in symptoms while using this herb. Like many other herbs, it should not be used during pregnancy or nursing. This herb should also be avoided while taking tetracycline antibiotics since berberine hinders the absorption of these drugs. Finally, since berberine may reduce blood sugar, do not use this herb without professional supervision if you take diabetes medications.