There is little good quality evidence on the effectiveness of herbal medicines, or how they might react with prescription medicines is available, the DTB reports. And, in general, 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. Published studies are often poorly designed, include too few participants, or don't last long enough to be of real value. Furthermore, the chemical make-up of various preparations of the same herb may differ, which can make it difficult to compare trial results.
Take black cohosh, for example. It is one of the most common herbal remedies for hot flashes yet study results on effectiveness have been mixed with some studies suggesting it works well and others suggesting it is worthless. It also carries the risk of liver toxicity, a fact which many users are unaware. Still, 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.
