What is butterbur?
Butterbur (Petasites hybridus) is an herb most commonly known for its use in migraine prevention, although it is falling out of favor due to the risk of liver toxicity.[3] Its name comes from its large hat-like leaves which historically were used to wrap butter to protect it from the weather. Butterbur typically grows in North America, Asia, and Europe within wet marsh areas or close to rivers or streams.[4]
What are butterbur’s main benefits?
Butterbur is most known for its use in migraine prevention, and several expert societies recommended it in the past but have since retracted their recommendation due to safety concerns.[1] Butterbur has also been used for allergic rhinitis and asthma.[1] For intermittent allergic rhinitis, taking 50 mg of butterbur extract containing 8 mg of petasins 2–3 times daily for 2 weeks reduced symptoms of runny nose, sneezing, and itching compared to a placebo.[2] Small studies have suggested that it may be comparable to cetirizine or fexofenadine,[5][6] but larger studies are needed to be sure. Studies of butterbur in asthma have been too short and too low-quality to draw conclusions.[7][8]
What are butterbur’s main drawbacks?
Common side effects of butterbur include burping, stomach upset, and headache, as well as allergic reactions, including itchy eyes and wheezing. People with allergies to ragweed and daisies (common causes of seasonal allergic rhinitis) may have allergic cross-reactivity to butterbur. Butterbur contains pyrrolizidine alkaloids, which are known to be toxic to the liver, and there have been rare reports of liver toxicity with butterbur use.[1][2]
How does butterbur work?
There are a few different proposed mechanisms for how butterbur helps to prevent migraine. First, the butterbur constituents petasin and isopetasin have been shown to reduce the constriction of blood vessels and decrease neuron excitation by inhibiting L-type voltage-gated calcium channels (which relax the smooth muscles that control the diameter of blood vessels). Additionally, independent of petasin content, butterbur extract has been shown to inhibit COX-2 enzymes, which produce inflammation-causing prostaglandins. Finally, some research suggests that butterbur root extract reduces the sensation of pain by acting on two types of ion channels that are also triggered by spicy food (TRPA1 and TRPV1).[1][9]
Dosage information
Most clinical studies have used 50–150 mg of butterbur extract daily in divided doses. For migraine prevention, dosages of 50–150 mg daily taken by mouth have been used. Note that if you use butterbur on a daily basis, it is important to monitor for signs of liver toxicity.[1]
For allergic rhinitis, 50 mg of butterbur extract two to three times daily seems to have some benefit.[2]
Frequently asked questions
Butterbur (Petasites hybridus) is an herb most commonly known for its use in migraine prevention, although it is falling out of favor due to the risk of liver toxicity.[3] Its name comes from its large hat-like leaves which historically were used to wrap butter to protect it from the weather. Butterbur typically grows in North America, Asia, and Europe within wet marsh areas or close to rivers or streams.[4]
Butterbur is most known for its use in migraine prevention, and several expert societies recommended it in the past but have since retracted their recommendation due to safety concerns.[1] Butterbur has also been used for allergic rhinitis and asthma.[1] For intermittent allergic rhinitis, taking 50 mg of butterbur extract containing 8 mg of petasins 2–3 times daily for 2 weeks reduced symptoms of runny nose, sneezing, and itching compared to a placebo.[2] Small studies have suggested that it may be comparable to cetirizine or fexofenadine,[5][6] but larger studies are needed to be sure. Studies of butterbur in asthma have been too short and too low-quality to draw conclusions.[7][8]
In a randomized controlled trial in 245 adults with 2–6 migraine headaches per month, the intention-to-treat (ITT) analysis showed that the participants who took 75 mg of butterbur extract twice a day had a greater decrease in migraine frequency compared to the participants who took a placebo (–45% vs. –28%). However, taking a smaller dose (50 mg of butterbur extract twice a day) was not significantly better than a placebo.[12]
The Canadian Headache Society strongly supports the use of butterbur extract for migraine prevention but warns that only properly tested products should be used. Unprocessed butterbur extract can contain pyrrolizidine alkaloids (PA), which are known to cause liver damage. It’s important to check that butterbur products are PA-free prior to use.[13] However, not all expert organizations agree with this recommendation. The American Headache Society and the American Academy of Neurology retracted their strong recommendations of butterbur due to concerns of liver toxicity. Furthermore, in both the United Kingdom and Germany, the use of butterbur is no longer authorized due to safety concerns.[1]
Common side effects of butterbur include burping, stomach upset, and headache, as well as allergic reactions, including itchy eyes and wheezing. People with allergies to ragweed and daisies (common causes of seasonal allergic rhinitis) may have allergic cross-reactivity to butterbur. Butterbur contains pyrrolizidine alkaloids, which are known to be toxic to the liver, and there have been rare reports of liver toxicity with butterbur use.[1][2]
There is a small risk that butterbur can cause liver toxicity, especially when used with hepatotoxic (toxic to the liver) medications, like acetaminophen, or in people with pre-existing liver conditions. Liver toxicity is likely caused by the known hepatotoxins pyrrolizidine alkaloids (PAs), which are supposed to be removed when the herb is processed for commercial dietary supplement use.[1] However, a 2012 study that tested 21 commercial butterbur supplements found that only 7 of the supplements contained no PAs, while another 7 contained toxic levels of PAs.[10] This might explain why there have been reports of hepatotoxicity in people taking commercial butterbur supplements that are supposed to be free of PAs. For example, there are 48 reports of mild to severe liver injury in people taking 50 to 225 mg of a commercially available butterbur extract daily for 4 to 730 days. Of these cases, 22 people were also taking other medications that can increase the risk of liver toxicity (such as acetaminophen). Severe liver toxicity seems to be more likely with long-term use and was reported in people who took butterbur for an average of 103 days.[11]
There are a few different proposed mechanisms for how butterbur helps to prevent migraine. First, the butterbur constituents petasin and isopetasin have been shown to reduce the constriction of blood vessels and decrease neuron excitation by inhibiting L-type voltage-gated calcium channels (which relax the smooth muscles that control the diameter of blood vessels). Additionally, independent of petasin content, butterbur extract has been shown to inhibit COX-2 enzymes, which produce inflammation-causing prostaglandins. Finally, some research suggests that butterbur root extract reduces the sensation of pain by acting on two types of ion channels that are also triggered by spicy food (TRPA1 and TRPV1).[1][9]
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