Scientists have found no strong evidence proving the efficacy of commonly taken herbal remedies in relieving troublesome menopausal symptoms.
In fact, for some of these medicines there is hardly any evidence at all, according to the researchers.
A large number of women experience vasomotor symptoms around the menopause, such as hot flushes and night sweats, prompted by the sharp fall in oestrogen levels.
Commonly used herbal remedies to relieve menopausal symptoms include black cohosh, red clover, Dong quai, evening primrose oil, and ginseng. Others include wild yam extract, chaste tree, hops, sage leaf, and kava kava.
However, according to the study, only a little good quality evidence on the effectiveness of herbal medicines, or how they might react with prescription medicines is available.
Generally speaking, safety has been under researched, which is a major concern given that herbal remedies are often assumed to be "safe" just on the grounds that they are "natural," said the authors.
Usually published studies are poorly designed, include too few participants, or don't last long enough to be of real value.
Also, the chemical make-up of various preparations of the same herb may differ, which can make it difficult to compare trial results.
The drugs regulator, the Medicines and Healthcare products Regulatory Agency (MHRA), has given a Traditional Herbal Registration to Menoherb, which contains black cohosh, under a scheme designed to boost the safety of herbal products on sale.
However, the authors said that clinical trial data on black cohosh are "equivocal," with some studies suggesting that the remedy works well, while others suggest that it does not relieve symptoms effectively.
One of the potential side effect of black cohosh is liver toxicity.
The authors said that there is "no convincing evidence" that red clover extract is effective.
Also little evidence is there one way or another for dong quai, evening primrose oil, wild yam, chaste tree, hops, or sage.
The study, titled 'Herbal medicines for menopausal symptoms' is published in the latest issue of the Drug and Therapeutics Bulletin (DTB).