After a year of deliberations, the UK-based Medicines Control Agency (MCA) has joined a growing list of authorities to ban the herbal relaxant, kava kava.
The ban, which came into effect in January, followed a public consultation period after which the Committee on Safety of Medicines (CSM) and the Medicines Commission found strong evidence linking kava kava with rare cases of liver toxicity. The MCA noted 70 reports of adverse liver reactions in various parts of the world, including four within the UK.
Other countries to have banned kava kava include Germany (where it is available by prescription only), Canada, Singapore (where it is classified as a poison), Australia and France. The FDA is investigating the herb in the US, where a voluntary ban is in place.
The MCA stated: "Investigations have been unable to identify factors that would predict which individuals are at risk of adverse reactions to kava kava and the mechanism of liver toxicity related to kava kava remains unknown." It added that it was not "reassured that the risk of liver toxicity could be reduced by measures such as label warnings."
Professor Alasdair Breckenridge, Chairman of the CSM, hinted the ban would not necessarily be final. "A prohibition on safety grounds can be reviewed at any time if new evidence emerges," he said, adding, "The MCA will undertake a specific review in two years time to assess whether this ban remains justified." Maurice Hanssen, director of the UK-based Council for Responsible Nutrition, said it was a disappointing decision. "We'll try and get kava back on the list when the Traditional Herbal Products Medicines Directive comes into play in the next year or two," he said.