What Is Butterbur?

What it is: Extracts of the root of this shrub-like plant (petasites hybridus) in the daisy family have been used to treat migraines in Europe for decades. When taken regularly, butterbur is thought to reduce migraine attacks by inhibiting proinflammatory substances and by reducing spasms in the walls of blood vessels in the brain. A few clinical trials have had promising results, including one in Neurology, which found that migraine sufferers who took butterbur (brand Petadolex) for four months reported a 48 percent decrease in frequency of headaches, compared with 26 percent of those given a placebo.

Of all alternative therapies evaluated for migraines by the American Academy of Neurology and the American Headache Society in a 2012 review of studies, butterbur was the only one “established as effective” in reducing the frequency and severity of migraines. The American Academy of Neurology classifies it as an effective drug for migraine prevention.

Other intended uses: To relieve allergies and treat allergic skin reactions or asthma. What the science says: No reliable scientific evidence supports the use of butterbur for skin allergies or asthma. May decrease nasal hay-fever symptoms and help prevent migraines.

Special precautions: Don’t take butterbur longer than 12 weeks; long-term safety is not established. Don’t use if you’re sensitive to ragweed and other plants in the daisy family (marigolds and chrysanthemums). The raw, unprocessed butterbur plant contains chemicals called pyrrolizidine alkaloids (PAs). PAs can cause liver damage and can result in serious illness. Only butterbur products that have been processed to remove PAs and are labeled or certified as PA-free should be used. Petadolex, made in Germany, is regulated as a drug by the government and is purified to contain no detectable levels of alkaloids.

Common side effects: Stomach upset, headache, drowsiness.

Possible interactions: None established.

Our advice: If you get migraines and conventional preventive strategies haven’t worked, butterbur may be worth a try. Petadolex is the safest option; you can’t be sure about other butterbur extracts, even if they make alkaloid-free claims.