An almost forgotten herb, butterbur (Petasites hybridus) was for many centuries associated with treating plagues, fevers, coughs, and gastrointestinal disorders. Over the past few years, butterbur has been rediscovered by modern science. The herb is now backed by compelling evidence from clinical trials, particularly from Germany, that have unlocked butterbur’s ability to reduce the frequency and intensity of migraine headaches, treat seasonal allergic rhinitis (sometimes called hay fever), and reduce bronchial spasms in asthma patients.
Recently, scientists have investigated the properties of butterbur and determined that the powerful plant compounds petasin and isopetasin that are contained in the leaves, rhizomes, and roots have antispasmodic, anti-inflammatory, and pain relieving actions.
Human studies show that these active components of butterbur, especially petasin, reduce smooth muscle spasms, particularly in the blood vessels of the head, which may explain butterbur’s effectiveness to reduce migraine episodes. Butterbur is beneficial for those suffering from allergic rhinitis by decreasing the amount of histamine and leukotriene, two chemicals produced by the body that cause swelling in nasal passages. Butterbur’s capability to subdue asthma may stem from its anti-inflammatory effects combined with its bronchodilating properties. The herb appears to suppress histamine-induced constriction of the smooth muscle lining respiratory passages, making breathing easier for asthmatics.
The unusual common name, “butterbur,” may be attributed to its large leaves that were once used to wrap up butter during hot weather. The size of its broad leaves, which may reach 2 to 3 feet across, helped define the herb’s generic name Petasites. The name is derived from the Greek word petasos, meaning “a wide broad-brimmed hat.”
Butterbur grows in moist places, especially beside water, throughout colder northern regions of Europe, as well as parts of Asia and North America. It has a creeping horizontal rhizome that spreads quickly, making the plant quite invasive. The moisture-loving perennial sends up small and tubular pink-lilac flowers on large spikes in early spring, before producing rhubarb like leaves.
Although butterbur contains therapeutic components, the plant itself should never be ingested. Butterbur contains compounds called pyrrolizidine alkaloids that are potentially toxic to the liver and may cause cancer. The highest concentrations of these alkaloids occur in fresh or dried butterbur roots and to a much lesser degree in the leaves. Use only products that are certified and labelled pyrrolizidine-free. Most studies used a 50 to 75 mg dose of butterbur standardized to deliver 7.5 mg petasin twice daily for 4 months.
Persons with liver disease, on anticoagulant therapy, barbiturates, or blood sugar lowering medications need to avoid all butterbur products, including pyrrolizidine-free formulations. It is not suited for pregnant and breast-feeding women, and young children.