The Negative Side Effects of Black Cohosh & Dong Quai

Herbalists have used both black cohosh and dong quai medicinally for centuries. Both herbs purportedly relieve gynecologic ailments ranging from symptoms of menopause to painful menstruation. Researchers believe that the plants contain estrogen-like properties that help replace the decreasing hormones in conditions such as menopause. While black cohosh and dong quai may have many benefits, you must also weigh the negative effects associated with ingesting these herbs. Always consult your physician before use of any herbal treatment.

An assortment of Chinese medicinal herbs.
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Abortifacient Properties

Most researchers warn against the use of both black cohosh and dong quai during pregnancy. The American Academy of Family Physicians explains that midwives have traditionally used the herbs to induce labor or to induce an abortion. Dong quai stimulates the uterus and helps to coordinate and strengthen contractions. Properties in black cohosh help the cervix to relax and open. Both of these herbs can cause a miscarriage or induce pre-term labor in pregnant women. You should never use these herbs during pregnancy or labor without a physician's supervision.

Drug Interactions

Herbs with estrogenic effects can often lessen the effects of hormone-based medications such as birth control pills, estrogen, progesterone, tamoxifen and raloxifene. Dong quai may also interfere with anticoagulant medications, increasing the risk of bleeding and bruising and may interact with other herbs, including feverfew, Chinese skullcap, turmeric, licorice, ginseng, ginger, garlic and ginkgo, according to the University of Maryland Medical Center. Using dong quai with St. Johns wort can increase your sensitivity to sunlight. There are no known interactions between black cohosh and prescription medications.

Side Effects

Taking black cohosh in recommended doses does not seem to cause side effects. However, large doses of the herb may cause headaches, abdominal pain, tremors, vision problems, vomiting, weight gain, slow heart rate and joint pain. There have been a few reported cases of liver toxicity after taking black cohosh, but there is insufficient evidence to prove the two incidents were related. warns that high doses of dong quai may increase your sensitivity to the sun, causing skin inflammation. You should avoid sunlight or use sunscreen while using dong quai.

Hormone-Related Disorders

The estrogen-like properties in black cohosh and dong quai may affect certain hormone-related conditions such as ovarian cancer, uterine cancer, breast cancer, prostate cancer and endometriosis. Researchers are conducting clinical trials to see if black cohosh stimulates or inhibits the growth of breast cancer cells. The National Institutes of Health explains that women with a history of breast cancer, or those with a familial history of the disease, should avoid using black cohosh unless under the supervision of a physician. If you have any of these conditions, you should avoid taking these supplements. There is no known connection between dong quai and breast cancer.

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