Up to 70 per cent of menopausal women in industrialised countries experience symptoms such as hot flushes and night sweats.
On average, such symptoms last for around four years, but in around one in 10 women, they can last more than 12 years, says a report in Drug and Therapeutics Bulletin (DTB). Understandably, many women seek to ease their discomfort with 'natural' remedies.
However, the authors say there is no strong evidence that some of the most popular herbal remedies work, and that some may even be harmful.
Herbal remedies commonly used to relieve menopausal symptoms include:
- black cohosh
- red clover
- Dong quai
- evening primrose oil
- wild yam extract
- chaste tree
- sage leaf
- kava kava
In general, safety of such herbs has been under researched, says the report, which is a major concern given that herbal remedies are often assumed to be safe, just on the grounds that they are 'natural'.
For example, 'Menoherb', a product containing black cohosh, has been given a Traditional Herbal Registration by the Medicines and Healthcare products Regulatory Agency (MHRA), under a scheme designed to boost the safety of herbal products on sale.
Yet clinical trial data on black cohosh are 'equivocal' says DTB, with some studies suggesting that the remedy works well, while others suggest that it does not relieve symptoms effectively. Worryingly, liver toxicity is also a potential side effect of black cohosh.
As for the other popular herbs, there is 'no convincing evidence' that red clover extract is effective, says DTB, and little evidence one way or another for dong quai, evening primrose oil, wild yam, chaste tree, hops, or sage.
Part of the problem stems from the fact that the chemical make-up of various preparations of the same herb may differ, which can make it difficult to compare trial results.
In addition, published studies are often poorly designed, include too few participants, or don't last long enough to be of real value.