Chasteberry is a shrub with violet flowers that grows on the hills and rivers of areas such as the Mediterranean and central Asia. Its Latin name is Vitex agnus-castus. The small brown fruit of the chasteberry plant is used medicinally.
The chasteberry's fruit is about the size of peppercorns and it has a peppermint-like scent. The word, chaste, which means sexually pure, was used by the ancient Romans to name this herb as they prepared chasteberry seeds for a drink to reduce the human sex drive. The plant is also called monk's pepper or monk's berry as monks in the Middle Ages also drank chasteberry mixtures in the hopes of reducing their sexual urges.
In modern times, the medicinal use of chasteberry began in the 1950s in Germany. The German Madaus Company manufactured an extract used in Europe for treating cyclic mastalgia, is premenstrual breast tenderness. The chasteberry used in the medicine is thought to stop the hormone, prolactin, from being released from the pituitary gland. Since prolactin stimulates milk production during pregnancy, it may also cause breast tenderness. High levels of prolactin are thought to be related to both irregular menstrual periods and amenorrhea, which is the absence of menstrual periods.
High prolactin levels are also associated with female infertility and studies on the use of chasteberry as a fertility treatment are mostly still exploratory at this point. It's important to note that Chasteberry is not considered safe to use in any way for women who are pregnant or nursing. Also, the herb may interfere with medicines such as bromocriptine used to treat pituitary conditions. Bromocriptine is a prolactin reducer that is sometimes used in infertility and premenstrual syndrome (PMS) treatments.
So far, there has not been much conclusive evidence that chasteberry can ease menopausal symptoms, but more studies are being conducted in this area. Chasteberry is still widely used in Germany; their governing systems that approve herbs are generally different from countries such as the United States. If too much chasteberry is consumed, side effects such as rashes, itching, headache and nausea are likely to occur.