Black cohosh and agnus castus are both thought to ease the difficulties of menopause and menstruation. Black cohosh belongs to the buttercup family. Agnus castus is more commonly called chasteberry. Though both plants have a history of medicinal use, that use is considered complementary medicine. Consult your doctor before taking either one.
The flowering parts of black cohosh and agnus castus look similar. Both have small, light-colored buds clustered on vertical stems. But, black cohosh is a tall plant and agnus castus is a small tree. Black cohosh grows in the eastern forests of North America, from Ontario to Georgia, reports the University of Michigan Health System. Agnus castus grows naturally in Central Asia and along the shores of the Mediterranean.
Harvesting and Preparation
The underground parts -- roots and below-ground stems called rhizomes -- of black cohosh are harvested for medicinal purposes, according to the National Center for Complementary and Alternative Medicine. They're used fresh and dried to prepare teas, tinctures, extracts, capsules and tablets.
The ripe berries of agnus castus are dried for medicinal use. The berries are dried, according to the National Center for Complementary and Alternative Medicine, and then used to make tablets, capsules or liquid extracts.
Black cohosh use in Native American medicine dates back at least 200 years, according to the University of Maryland Medical Center. It was a common home remedy in 18th-century American households, and gained widespread use in Europe during the latter third of the 20th century. Black cohosh is sometimes called snakeroot, rattleroot and bugwort.
According to legend, agnus castus acquired the common name of chasteberry because the berries were thought to ensure chastity. During the Middle Ages, monks allegedly used agnus castus to diminish their sexual desires, according to the National Center for Complementary and Alternative Medicine. In addition to the name chasteberry, agnus castus is known as chaste tree berry, chaste tree fruit and monk’s pepper.
Black cohosh is purported to ease menstrual problems such as irregularity, premenstrual syndrome and heavy menstruation. It may also help menopausal symptoms such as hot flashes, night sweats and vaginal dryness. Other potential uses include help for arthritis and osteoporosis, according to the University of Maryland Medical Center. Further research and clinical trials are needed for all purported black cohosh uses.
Like black cohosh, agnus castus may prove useful for menstrual problems. It could potentially help to ease painful menstruation, breast pain and bloating, reports Memorial Sloan-Kettering Cancer Center. It cautions that the safety of long-term use remains in question because of agnus castus's active hormones. Other historical uses of agnus castus include increasing breast-milk production and treating acne and infertility, according to the National Center for Complementary and Alternative Medicine.
Don't take black cohosh if you've been diagnosed with an estrogen receptor-positive cancer, warns Memorial Sloan-Kettering Cancer Center. Potential estrogenic activity of black cohosh remains unknown. Black cohosh may also interfere with birth control pills. The side effects of black cohosh may include liver failure, headache, rash and gastrointestinal discomfort.
Don't take angus castus if you are pregnant or have hormone-sensitive cancer. Agnus castus may compromise the effectiveness of birth control pills and dopamine D2-antagonists, according to Memorial Sloan-Kettering Cancer Center. Agnus castus side effects could include hives, rash, agitation, nausea and headache.