serotonin. Scientists call this type of chemical a neurotransmitter because it helps the brain send messages to other parts of the body.
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Black cohosh root also seems to have some effects similar to the female hormone, estrogen. In some parts of the body, black cohosh might increase the effects of estrogen. In other parts of the body, black cohosh might decrease the effects of estrogen. Estrogen itself has various effects in different parts of the body. Estrogen also has different effects in people at different stages of life. Black cohosh should not be thought of as an "herbal estrogen" or a substitute for estrogen. It is more accurate to think of it as an herb that acts similar to estrogen in some people.
Black cohosh can cause some mild side effects such as stomach upset, cramping, headache, rash, a feeling of heaviness, vaginal spotting or bleeding, and weight gain.
There is also some concern that black cohosh may be associated with liver damage. It is not known for sure if black cohosh actually causes liver damage. Researchers are studying this. Until more is known, people who take black cohosh should watch for symptoms of liver damage. Some symptoms that may suggest liver damage are yellowing of the skin and eyes (jaundice), unusual fatigue, or dark urine. If these symptoms develop, black cohosh should be stopped and a health provider should be contacted. People who take black cohosh should talk with their health provider about getting tests to make sure their liver is working well.
Special Precautions & Warnings:Pregnancy or breast-feeding: Black cohosh is POSSIBLY UNSAFE when used during pregnancy or breast-feeding. Since black cohosh acts somewhat like a female hormone it might increase the risk of miscarriage.
Breast cancer: There is some concern that black cohosh might worsen existing breast cancer. Women who have breast cancer or who have had breast cancer in the past, and women at high-risk for breast cancer, should avoid black cohosh.
Hormone-sensitive conditions, including endometriosis, fibroids, ovarian cancer, uterine cancer, and others: Black cohosh acts somewhat like the female hormone, estrogen, in the body. There is some concern that it could worsen conditions that are sensitive to female hormones. Do not take black cohosh if you have a condition that could be affected by female hormones. These conditions include ovarian cancer, uterine cancer, endometriosis, fibroids, and other conditions.
Liver disease: Some reports suggest that black cohosh might cause liver damage. It is not known for sure if black cohosh is the cause of liver damage in these cases. Until more is known, people with liver disease should avoid taking black cohosh.
Kidney transplant: Taking a product containing black cohosh plus alfalfa has been linked to a report of kidney transplant rejection. It is not known if black cohosh is the cause of this rejection. Until more is known, people who have received a transplant should avoid black cohosh.
Protein S deficiency: People with a condition called protein S deficiency have an increased risk of blood clots. Due to the hormone-like effects of black cohosh, there is some concern that black cohosh might also increase the risk of blood clots. There is a report linking blood clots in someone with protein S deficiency after taking black cohosh along with several other herbal products. Until more is known, people with protein S deficiency should avoid black cohosh.
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