Black Cohosh for Menopausal Vasomotor Symptoms
Black cohosh is not recommended for the treatment of menopausal hot flashes because randomized controlled trials have consistently failed to demonstrate efficacy, and case reports of hepatotoxicity raise safety concerns. 1, 2, 3
Evidence Against Efficacy
The highest-quality evidence shows black cohosh does not work:
A 2012 Cochrane systematic review of 16 randomized controlled trials (2,027 women) found no significant difference between black cohosh and placebo in hot flush frequency (mean difference 0.07 flushes per day; 95% CI -0.43 to 0.56; P=0.79) or menopausal symptom scores (SMD -0.10; 95% CI -0.32 to 0.11; P=0.34). 3
A randomized, double-blind, placebo-controlled crossover trial specifically testing black cohosh for hot flashes showed no significant differences between groups in symptom improvement. 1
The National Comprehensive Cancer Network (NCCN) explicitly states that black cohosh is not recommended due to lack of efficacy in randomized trials. 2
Limited data show possible benefit in the general population, but randomized trials in breast cancer survivors—a population with severe vasomotor symptoms—show no benefit. 4
Safety Concerns
Beyond lack of efficacy, black cohosh carries hepatotoxicity risk:
The Annals of Oncology guidelines cite reports of liver failure associated with black cohosh use, making it an unsafe choice even if efficacy were established. 2
Adverse reactions documented in clinical trials include nausea, vomiting, headaches, dizziness, mastalgia, and weight gain, with adverse symptoms occurring in 5.4% of users. 5, 6
Single cases of acute hepatocellular damage have been reported, though causality remains unclear. 6
Recommended Alternatives
Instead of black cohosh, use evidence-based nonhormonal therapies:
First-Line Pharmacologic Options
Gabapentin 900 mg/day at bedtime reduces hot flash severity by 46% versus 15% with placebo (high-quality evidence), with no drug interactions and no absolute contraindications. 2, 7
Venlafaxine 37.5 mg daily, increasing to 75 mg after 1 week, reduces hot flash scores by 37-61% and is preferred by 68% of patients over gabapentin despite similar efficacy. 2, 7
Paroxetine 7.5-20 mg daily reduces hot flash frequency by 62-65%, but must be avoided if the patient is taking tamoxifen due to CYP2D6 inhibition that reduces tamoxifen efficacy. 2, 7
Nonpharmacologic Options
Acupuncture is safe and effective, with some studies showing equivalence or superiority to venlafaxine or gabapentin. 2, 4, 7
Weight loss of ≥10% of body weight may completely eliminate hot flash symptoms in overweight women. 2, 4
Paced respiration training (structured breathing exercises) for 20 minutes daily shows significant benefit. 2, 7
Cognitive behavioral therapy (CBT) reduces the perceived burden of hot flashes even when frequency remains unchanged. 2
Monitoring and Switching Strategy
- Review efficacy at 2-4 weeks for SSRIs/SNRIs and 4-6 weeks for gabapentin; if the agent is intolerant or ineffective, switch to another nonhormonal agent. 2, 7
Hormone Therapy Considerations
If nonhormonal options fail and the patient has no contraindications:
Menopausal hormone therapy (MHT) is the most effective treatment, reducing hot flashes by approximately 75% compared to placebo, but should only be used when nonhormonal options fail. 2, 7
Transdermal estrogen formulations are strongly preferred over oral preparations due to markedly lower rates of venous thromboembolism and stroke. 2
Screen for absolute contraindications before prescribing: history of breast cancer or hormone-dependent malignancies, active or recent venous thromboembolism, prior stroke or myocardial infarction, active liver disease, unexplained vaginal bleeding, and pregnancy. 2
Clinical Pitfalls to Avoid
Do not prescribe black cohosh based on patient requests for "natural" treatments—the evidence does not support its use, and hepatotoxicity risk makes it unsafe. 2, 3
Recognize the robust placebo response (up to 70% in some studies) when patients report subjective improvement with unproven therapies. 2
Many hot flashes improve spontaneously over time with ongoing treatment, which can be misattributed to ineffective interventions like black cohosh. 2
If the patient insists on a "natural" option with minimal efficacy, vitamin E 800 IU daily is safer than black cohosh, though doses >400 IU/day are linked to increased all-cause mortality and should be avoided. 2, 4