Black cohosh (also known as squawroot, black snake root, or bugbane) is a perennial plant native to open woods and hillsides of eastern North America from Ontario to the southern United States. Growing up to 3 meters in height, the plant has a smooth, furrowed stem and toothed, oval-shaped leaflets arranged in groups of two to five along a common petiole. Black cohosh flowers from June to August, bearing long clusters of small white flowers. The thick, knotty, black rootstalk of the plant is harvested in the fall and dried for health purposes.
Germany's Commission E has approved black cohosh root for treatment of premenstrual discomfort, painful menstruation, and menopausal symptoms. Although there is little scientific data to substantiate the efficacy of black cohosh for PMS or painful menstruations, research suggests that the herb may be effective for menopausal symptoms such as hot flashes, profuse sweating, sleep disruption, and depressive moods.
The active constituents in black cohosh root are a group of compounds known as triterpene glycosides, of which 16 have been isolated and identified. Black cohosh root extracts are commonly standardized to contain 5 percent triterpene glycosides.
For menopausal symptoms, a common recommendation is 1 to 2 grams per day of powdered dried root, or extracts providing the equivalent. Black cohosh has no known toxicity and is generally well tolerated at this dosage range, although a small percentage of users may experience gastric discomfort. Intake of very high dosages (5 grams) can cause vomiting, headache, dizziness, limb pains, and lowered blood pressure.