A butterbur is a medicinal herb that is used to treat headaches, gastrointestinal illnesses, anxiety, insomnia, fever, coughs and asthma, according to WebMD. The roots, bulbs and leaves of the butterbur plant contain natural chemicals referred to as pyrrolizidine alkaloids that help to minimize inflammation.
Drugs.com explains that clinical trials have shown that butterbur doses ranging from 50 to 75 milligrams per day can help minimize symptoms of allergic rhinitis and migraine headaches. Potential serious side effects of butterbur include liver enzyme damage and congestive heart failure.
The University of Wisconsin-Madison School of Medicine and Public Health explains that butterbur treatments originated in the Middle Ages and the herbal medicine was commonly used to treat symptoms of the plague. Mild side effects of butterbur include gas and stomach pain.