Do black cohosh or red clover help against hot flushes in menopause?
Standardised black cohosh moderately but demonstrably reduces hot flushes and menopausal complaints better than a placebo, and appears to be safe. Red clover has too little individual evidence to recommend.
Black cohosh helps with hot flushes. That is shown by a meta-analysis of 22 randomised studies involving 2,310 women1. The effect on hot flushes is moderate, but the effect on broader complaints such as night sweats is larger.
The best-studied form is a standardised extract, also known as the iCR extract. A large systematic review of 35 studies involving nearly 44,000 women compared this with a placebo pill2. The benefit was clearly present and comparable to a low-dose oestrogen patch. Hormone levels and sensitive tissues such as breast and uterine lining remained unchanged. There were no indications of liver problems. Note: non-standardised products offer less certainty about what you are actually taking in.
Black cohosh does not have a demonstrable effect on mood and anxiety complaints. Those effects were not significant in the meta-analysis. If you suffer from those complaints, black cohosh will do little for you.
Red clover is a different story. There are no individual studies that have tested red clover for hot flushes or night sweats. Review articles describe both its efficacy and its safety as controversial, and there is no clarity on the correct dosage3,4,5. Based on the current evidence, red clover cannot be recommended.
Combination preparations containing black cohosh and other plant extracts showed substantial improvements in hot flushes and sleep in two small studies (90 and 101 women)6,7. But with a combination product you do not know which component is doing the work. Those results therefore say nothing about red clover or soy isoflavones individually.
Black cohosh: a meta-analysis of 22 randomised studies (n=2,310; PMID 37192826) and a large systematic review of 35 studies (n=43,759; PMID 33021111) provide the strongest evidence. Two smaller randomised studies (n=90 and n=101) apply to combination preparations (PMID 40131516, 33331798). Red clover: no separate primary studies available; mentioned only in review articles that describe efficacy and safety as controversial (PMID 39477563, 36792552, 27929271).