BACKGROUND:Butterbur leaves, which can be up to a metre wide, and are distinctive along riverbanks and in wetlands. The plant has been called bog rhubarb, and its scientific name, Petasites hybridus, comes from a Greek word meaning broad-brimmed hat. Its use for allergic reactions was examined in this column earlier, but it has also been attracting attention in the treatment of migraine.
Migraines affect about 10 per cent of the population, with women three times more likely to suffer from them as men. Much remains unclear about their causes and treatment. Lifestyle factors are associated with them, including sleep, stress, diet and exercise. Adjustments in these should be tried to see if anything brings relief. Once migraines begin, various pharmaceuticals are available to treat the symptoms. Butterbur is not recommended at this stage, but is a later way to reduce their occurrence.
EVIDENCE FROM STUDIES
Different compounds have been extracted from butterbur that are anti-inflammatory or cause blood vessels to relax. These effects may contribute to preventing migraines. The past decade has seen a small number of controlled trials of butterbur for migraines. Most research has been sponsored by the German manufacturer of a patented product called Petadolex.
The first controlled trial enrolled adults who had been having two or three migraines a month for at least a year. After 12 weeks those taking 50mg of butterbur twice a day had significantly fewer migraines. When migraines did occur they were initially shorter and less intense, but by the end of the study these benefits were no longer recorded.
A larger study examined the use of a higher dose. More than 200 adults were randomised into three groups; then twice daily they took 50mg of butterbur, 75mg of butterbur or a placebo. The higher dose led to significantly fewer migraines compared with the two other groups, but those on the lower dose did no better than those taking placebo.
Two studies have also examined the use of butterbur for children with migraines. One study found that many children taking butterbur had fewer and less severe migraines. However, no control group was used here and there was no blinding.
The second study compared butterbur with music therapy and placebo. After 12 weeks the children receiving music therapy had significantly fewer migraines than those in either of the two other groups. Six months after treatment stopped, the children who took butterbur had as few migraines as those in music therapy. These studies had design problems, which limits their usefulness.
PROBLEMATIC ASPECTS
In the controlled studies no serious adverse events were reported. Minor gastrointestinal problems were noticed, with burping reported by 20 per cent of the participants. Little is known about the long-term effects of taking butterbur, as trials have lasted only 12 weeks.
The underground rhizomes of butterbur contain pyrrolizidine alkaloids, which are liver toxins. The commercial product used in the above studies, Petadolex, is tested to ensure it contains no pyrrolizidine alkaloids.
RECOMMENDATIONS
In 2009 the European Federation of Neurological Societies updated its guidelines for professionals caring for those with migraines. Conventional medicines remain the medicines of first choice for preventing migraines, but butterbur was among the second-choice treatments.
Butterbur has been studied only for the ongoing prevention of migraines, not for their treatment after they develop. Given the lack of information on long-term effects, treatment should be tapered after a few months and restarted if migraines become more frequent again.
As numerous commercial butterbur products are available, check that the labels declare that all pyrrolizidine alkaloids have been removed. The plants themselves should not be consumed because of these toxins.
Dónal O’Mathúna has a PhD in pharmacy, researching herbal remedies, and an MA in bioethics, and is a senior lecturer at DCU’s school of nursing
