What Are the Side Effects of Black Cohosh?

Black cohosh is an herb that has been used for a long time throughout the US and Europe for cough, cold, infertility and menopause symptoms. The side effects of black cohosh include gastrointestinal upset, skin rash, breast pain, brain enlargement, infection, vaginal bleeding/spotting and joint or muscle pain.

People in the US and Europe have used the herb black cohosh since ancient times for a variety of illnesses ranging from cough and cold to infertility. It has been most commonly used for menopause and found to be beneficial. Other problems include menstrual cramps and menstrual irregularities. Much of the research on black cohosh has been on menopause. Some studies show black cohosh effective for relieving the following symptoms of menopause

• Hot flashes (most effective for this symptom as reported by women)
• Night sweats
• Vaginal dryness

In a study, black cohosh has worked as effectively as hormonal replacement therapy in the management of postmenopausal symptoms. But some other studies have found its effect to be similar to a placebo. The data on its efficacy are mixed. 

The most comprehensive research on black cohosh to date has been the study published in the Cochrane Database of Systematic Reviews in 2012. The review concluded that there is not enough evidence to state whether black cohosh is effective or ineffective to help treat the symptoms of menopause. Given this, the reviewers suggested the need for further research on black cohosh. 

The problem with these studies is the inconsistency in variations of the chemical composition of the products containing black cohosh.

Scientists have yet to find the active ingredients in black cohosh and also its potential mechanism(s) of action. It is unclear whether black cohosh has any effects on the vagina and uterus.

Based on the different compounds present in black cohosh, experts have proposed the following theories of how black cohosh works in the body.

• Estrogen-like properties: Estrogen is a female hormone, the level of which declines in menopause. Its reduced levels are responsible for all the signs and symptoms of menopause. Some experts believe that black cohosh works like estrogen in the body and helps ease menopause symptoms. 
• Action on the brain: Black cohosh can work on nerves in the brain to increase serotonin levels, which can help improve mood and help treat depression and anxiety in menopause.
• Anti-inflammatory and antioxidant properties: The properties of black cohosh help the body fend off chronic illnesses.

There is insufficient evidence to recommend it for uses other than for menopause. 

Black cohosh is available in the market as capsules and tinctures. The recommended dose is between 20 and 80 mg of black cohosh extract once or twice daily for up to six months. 

From the several studies done on black cohosh, it is found to be associated with few adverse reactions. The reported side effects include

• Gastrointestinal upset
• Skin rash
• Breast pain
• Brain enlargement
• Infection
• Vaginal bleeding/spotting
• Joint or muscle pain

The duration of all the studies conducted on black cohosh is six months or less. Safety data on the long-term use of black cohosh are lacking. Hence, physicians often recommend taking the black cohosh for no more than six months. 

Black cohosh is not safe for everyone. There are several reports of patients with some bad effects on the liver such as

• Hepatitis (infection of the liver)
• Liver failure
• Abnormal liver function tests

Physicians recommend avoiding black cohosh if you have any problem with your liver. Always use it under medical supervision. Discontinue its use and consult your doctor if you develop symptoms of liver trouble, such as abdominal pain, dark urine or jaundice.

Due to its possible estrogen-like activity, black cohosh may interact with hormone replacement therapy or oral contraceptive pills. Black cohosh may also interact with other drugs such as

• Cholesterol-lowering drugs
• Drugs that can cause hepatotoxicity (harmful for liver), such as
  • Acetaminophen
  • Amiodarone
  • Carbamazepine
  • Isoniazid (INH)
  • Methotrexate
  • Methyldopa
  • Fluconazole
  • Itraconazole
  • Erythromycin
  • Phenytoin
• Medications that change in the liver. Examples include
  • Amitriptyline
  • Clozapine
  • Codeine
  • Desipramine
  • Donepezil 
  • Fentanyl
  • Prozac (fluoxetine)
  • Metoprolol 
  • Olanzapine
  • Ondansetron
  • Tramadol
• Cisplatin (medication for cancer)

Black cohosh differs from blue cohosh and white cohosh concerning its actions. Do not confuse these drugs. Unlike black cohosh, blue cohosh and white cohosh are toxic.

Remember to look for certifications provided by Consumer Labs, The U.S. Pharmacopeial Convention or NSF International while choosing preparations of black cohosh and all other supplements in general.