The medicinal herb vitex, also known by the common names chasteberry and monk's pepper, has been used for hundreds of years as a component of naturopathic medicine. For men, vitex has been used most commonly as an anaphrodisiac, or a product to reduce sex drive. Women traditionally used vitex to treat menstrual problems, infertility and complications of pregnancy. Despite its historic use, vitex has been the subject of relatively little research. There is no compelling evidence supporting or refuting its safety during pregnancy.
Scientists are currently uncertain about how vitex affects the human body. The National Centers for Complementary and Alternative Medicine suggests that it may operate by affecting levels of female reproductive hormones, such as estrogen and testosterone. It also appears to affect the neurotransmitter dopamine, which influences mood and certain reproductive activities. There is no available research determining how these effects might influence the viability of a pregnancy or the development of a fetus.
In modern naturopathy, vitex is most noted for its use as a treatment for premenstrual syndrome, or PMS. A well-designed 2001 study published in the "British Medical Journal" found that vitex relieved several common symptoms of this condition, including mood disruptions and physical discomfort. Because similar problems are common during pregnancy, it is at least plausible that vitex can ease these discomforts during gestation. However, no studies have investigated chasteberry's specific benefits to pregnant women.
The NCCAM specifically advises against the use of vitex during pregnancy, noting that its hormonal effects could be detrimental to the mother or unborn child. Although there is no clear evidence of risk, it is possible that vitex might increase the risk of birth defects. Hormonal effects associated with vitex could also lead to preterm labor, postterm labor, or other pregnancy complications. Well-designed clinical trials are needed to determine vitex's impact on fetal development and on gestation itself.
General Side Effects
Even in nonpregnant individuals, vitex can lead to certain uncomfortable side effects. According to the NCCAM, however, vitex has not been known to cause serious side effects. Minor problems such as dizziness, rash and digestive upsets are among the most common problems associated with the herb. As a precaution, women should generally avoid vitex supplements unless they are under a health care provider's guidance, particularly during pregnancy and lactation. Only a qualified practitioner can make an appropriate decision regarding the use of medicinal herbs.