butterbur

Common name
Butterbur, purple butterbur, Western coltsfoot, butter dock, Arctic butterbur, bog rhubarb, pestilence wort
Botanical names
Petasites hybridus, Petasites frigidus
Parts used and where grown
Butterbur, or Petasites hydridus, is found in colder, northern regions of Russia and Europe. A species native to the northern United States and much of Canada is Petasites frigidus. All parts of either plant can be used, including root, rhizome, leaves, and flowers. Both species are easily confused with their close cousin, Eastern coltsfoot (Tussilago farfara), a plant that looks the same and has similar properties and hazards.
Butterbur has been used in connection with the following conditions (refer to the individual health concern for complete information):
Science Ratings - Health Concerns
*** - Hay fever
*** - Migraine headache
** - Asthma
*** - Reliable and relatively consistent scientific data showing a substantial health benefit.
** - Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
* - For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support and/or minimal health benefit.
Historical or traditional use (may or may not be supported by scientific studies)
Traditionally the entire plant was used as a demulcent to soothe a dry, spasmodic
cough.1 It was primarily made into a tea, and used only for short periods of time. Using the herb as a tea may have helped reduce the liver’s exposure to butterbur's toxic compounds, as they are not normally water soluble.
Active constituents
Butterbur contains petasins, a group of bitter-tasting compounds in a class of chemicals called sesquiterpenoids. Petasine is a specific petasin considered important in butterbur. Petasins relax blood vessels and various smooth muscles in the body, such as those that are found in the uterus and lungs, according to test tube and animal studies.2 Petasins are also known to reduce inflammation, as demonstrated in human studies.3 Because of these properties, butterbur might be expected to be beneficial for people with
migraines and asthma. Butterbur extracts have consistently been shown to reduce symptoms in people with migraines more effectively than placebo. Butterbur has also been shown to help people with asthma, although the results have been conflicting.4 5 6 Some studies have also shown that butterbur extract works just as well as a common antihistamine drug for people with hay fever, but without causing drowsiness.
Butterbur also contains unsaturated pyrrolizidine alkaloids. These can cause severe liver damage in some people if taken for too long. Only extracts that exclude pyrrolizidine alkaloids should be used.

How much is usually taken?
The most commonly available product is an extract of the rhizome of Petasites hybridus standardized to contain 7.5 mg of petasine per capsule. This type of extract removes the pyrrolizidine alkaloids to avoid causing liver damage. Intake is usually 1 to 2 capsules three times per day.

Are there any side effects or interactions?
There are no known side effects as long as pyrrolizidine alkaloids are not present. When they are present, they can cause serious liver damage and even liver failure or death. Therefore, pyrrolizidine alkaloid–containing extracts should not be used.
At the time of writing, there were no well-known drug interactions with butterbur.

Source: www.cncahealth.com