Butterbur is a perennial plant native to Europe, Asia and northern Africa, and it has a long history as an herbal remedy in folk medicine. Its Latin name is Petasites hybridus, and it belongs to the Asteraceae family of plants. It is also known as sweet coltsfoot, bog rhubarb, devil's hat and many other names. Butterbur flowers in early spring with green, white or pale pink flowers growing in clusters on a spike that is 2-4 inches (5-20 cm) long. The plant has very large, round leaves with a diameter of 15-27 inches (40-70 cm.), and one possible explanation for its name is that the leaves were once used to wrap butter in.
It is a creeping plant with a thick, extensive root system, and it prefers to grow in moisture-rich areas such as riverbeds, ditches and marshes. All parts of the plant contain toxic alkaloids that can cause cancer and liver damage. In spite of its toxic nature, butterbur has been used as a medicinal plant for at least 2,000 years and is still being used. It has been used to treat skin ulcers, water retention, coughs, fever, headaches, asthma, arthritis, stammering and various other ailments. In medieval Europe, it was even used to treat the plague, probably explaining one of its many names: pestilence wort.
Anyone interested in taking butterbur should proceed with caution because of the toxins present in the raw plant. Herbal products containing butterbur should have been treated to remove these toxins, but even then, the herb might cause side effects such as itchy skin and eyes, upset stomach, wheezing and fatigue. One should consult a medical professional before taking any products containing butterbur, and pregnant or nursing women are advised to avoid it completely.
The active, medicinal substances in butterbur are thought to be petasine and isopetasine. Some research suggests that these substances have anti-inflammatory as well anti-spasmodic properties and that they might also improve blood flow. Scientific studies of butterbur's effectiveness as a treatment for various medical problems have been mostly inconclusive, but there have been some positive results when it comes to migraines. An extract derived from the plant has been shown to be somewhat effective in preventing migraine attacks as well as in reducing the frequency and severity of such attacks. Studies also have been done to see whether butterbur can ease the symptoms of some allergies, such as hay fever, but the studies have been small, and the results are not conclusive.