The study on 245 migraine patients found that the herbal extract from the petasites hybridus root halved the frequency of migraine attacks in many of the sufferers. It lends scientific weight to the traditional use of the remedy.
Study leader Dr Richard B. Lipton of the Albert Einstein College of Medicine of Yeshiva University and colleagues randomly assigned the patients, who experienced two to six migraine attacks per month during the three prior months, to take two capsules daily over the next four months.
They took 75 mg of Petadolex brand butterbur extract made by Weber & Weber, a 50-mg dose, or a placebo.
The main outcome measured was the percentage decrease in the frequency of migraine attacks, calculated by comparing migraine attacks during the study with the number of attacks that patients experienced before the study began.
"The 75-mg butterbur dose reduced headache frequency by 48 per cent - a substantial treatment effect," said Dr Lipton.
This compared with a 26 percent reduction among placebo users, reported the team in the 28 December issue of Neurology 63(12), pp2240-4.
Also the 75-mg dose reduced headache frequency by 50 per cent or more in over two-thirds of the migraine sufferers. The 50 mg dose was not significantly more effective than placebo on the primary study endpoints.
Dr Lipton said that butterbur was "a welcome addition to the therapeutic arsenal we have available to combat migraine".
About 12-15 per cent of people in the UK, (around 9 million people), suffer from migraines, with twice as many women as men affected by the complaint. The symptoms are often severe and debilitating, lasting anywhere between four and 72 hours.
There were few adverse effects from butterbur. Those most commonly reported that may have been related to butterbur treatment were gastrointestinal in nature, mainly burping.
The study was conducted at nine centres in the United States and Germany.