There is a fair amount of scientific evidence from butterbur research suggesting that the supplement may really work for preventing migraine headaches in adults. The studies used one particular product (Petadolex®) that was purified to remove toxic alkaloids naturally found in butterbur and standardized to contain a consistent amount of the active components. Early evidence suggests that this particular product may also be effective for preventing migraines in children as young as six years old.
Research studies have shown inconsistent results when using butterbur to treat allergies, but these inconsistencies may reflect differences in study design or differences among butterbur products. In general, the bulk of this preliminary evidence seems to suggest that butterbur might actually be effective for treating allergy symptoms.
There is not enough scientific evidence to suggest that butterbur really works for any other use.
(Click Does Butterbur Work? for more information on butterbur research. This article further discusses whether the herbal supplement really works and describes research studies in more detail.)