A number of studies have now shown that an herbal medicine called Butterbur (Petasites hybridus) reduces migraine headaches. This means it reduces both intensity and frequency of migraines.
But what about the warning by some about Butterbur herb being harmful to the liver? We’ll discuss the evidence showing that this is not a fair evaluation of commercially available extracts of this herb from reputable manufacturers and have been proven to be safe.
In this article
Clinical research with migraine sufferers
Multiple human studies have tested a Butterbur extract called Petadolex®. In a 2004 study from the Albert Einstein College of Medicine, researchers tested 245 migraine patients between 18 and 65 years old. The patients had between two to six migraine attacks per month. Half were given the supplement and the other half were given a placebo.
The research found that after four months of treatment with the herbal supplement, 68 percent of the patients had a reduction greater than or equal to 50 percent in their migraine frequency. The best results were found among those taking 150 milligrams per day, in two doses of 75 milligrams.
Another study, also a randomized, placebo-controlled, double-blind trial, studied 60 patients with migraines. Here the subjects took 100 milligrams of Petadolex® per day for three months (12 weeks).
Those patients taking the Butterbur supplement reported significant reductions in migraine frequency. 45 percent of the patients receiving the herbal extract reported reduction frequency of equal to or more than half of the migraines they experienced before the trial began.
Another study studied 63 elementary children (between 8 and 12) who experienced regular migraines for at least a year. In this study the children were given different doses, from 50 milligrams per day to 150 milligrams per day of Petadolex® over a three-month period (12 weeks). They were monitored for eight weeks and 6 months after the treatment.
In this study, those taking the Butterbur extract had significantly fewer migraines both in the 8 weeks after the treatment and 6 months after the treatment.
In all the above studies, the herbal treatment was deemed safe, with few side effects.
What’s in Butterbur herb?
Just like most medicinal herbs, Butterbur contains numerous active compounds. The primary active compounds contained in the roots and leaves are called petasins. These are technically known as sesquiterpenes and they include S-petasin, iso-S-petasin, neo-S-petasin and others.
The research has also isolated more than 20 different compounds classified as eremophilanes in this medicinal herb.
The herb also contains a number of essential oils and also contains oxopetasans, bakkenolides, petasitene and pethybrene, eremophilanes, furanoeremophilanes among other compounds.
Many of these compounds have been classified as neuroprotective – meaning they benefit the nerves and nervous system. They can help prevent nerve injury and help protect neurons from being damaged.
This has been shown in the research. Studies have shown that petasins are neuroprotective. And sequiterpenes bakkenolides in Butterbur have been shown to help protect the nerves and brain from nerve damage by blocking a compound called nuclear factor-κB.
Butterbur has also been shown to contain a number of antioxidants. Antioxidants help protect the brain and nerves from damage from free radicals. Some of the antioxidants from this herb include quercetins, rutin, caffeic acid, petasiformin, petaslignolide, chlorogenic acid, fukinolic acid, quinic acid and kaempferol. Each of these are potent antioxidants to help protect the brain and nerves.
What about the liver warnings?
Butterbur has indeed been the brunt of criticism for a potential to harm the liver. This is an unfair criticism to this herb’s commercial extracts, however.
The compound that is being warned against is called “Pyrrolizidine alkaloids” or PAs.
Yes, raw unprocessed Butterbur will often contain Pyrrolizidine alkaloids. However, a number of other foods and herbs can also contain PAs. These include popular consumer foods and herbal products such as honey, cumin (a key ingredient in curry), oregano, black tea, rooibos, anise, lemon balm, chamomile, thyme, peppermint, lemon verbena and many other herbs and foods. Many grains and flours can also contain them, depending on where they are farmed. This is because there are a variety of pollen-producing flowers from plants known to contain PAs that can grow around and within grain fields.
In addition, many traditional herbs contain PAs. One study found that PAs were present in significant amounts in about 3 percent of all the plants that grow around the world.
The bottom line is that a strict warning against using Butterbur because of its PA levels would mean that we also couldn’t eat raw honey and many of the most popular herbs and even black tea for fear of some kind of liver damage. Yes, it should be noted that billions of people are drinking black tea, honey, cumin, peppermint, chamomile and grains known to contain PAs every single day.
It is important to know that these natural compounds also contain significant antioxidants, which can significantly reduce the effects of PAs on the liver.
Yes, this has been shown in the research. In a 1982 study, mice were given an abundant quantity of PAs (280 milligrams per kilo of body weight). Some mice were also given one or a combination of three antioxidants: butylated hydroxyanisole (BHA), ethoxyquin, and cysteine.
Those mice given this significantly large quantity of PAs died, but those given the same PAs plus the antioxidants did not die. The antioxidants protected the mice from PA-driven death, even though this quantity of PAs was toxic to them without the antioxidants.
First, we should translate this to reality. Most of the foods and herbs mentioned above along with Butterbur contain very minute amounts of PAs. We are talking about micrograms per kilogram of the food or herb. (1 milligram equals 1,000 micrograms)
For example, in 2020 the European Union set maximum safe standards for herbs and foods for PA content. These limits ranged from 1,000 micrograms for some herbs to 1 microgram for products consumed regularly by children. These are very small amounts compared to how much were given the mice – 380 milligrams per kilo of body weight. This means 1 microgram of PAs in black tea would require 380,000 cups of black tea multiplied by the body weight of a child, let’s say 50 kilos, would require them to drink 19 million cups of black tea at a time to get to this minimum level if the black tea had 1 microgram of PAs.
But also noting that the EU has regulated this compound in foods and herbs, this also means that reputable food and herbal suppliers must test for PA levels in their products. And if levels are over these limits, they would need to reduce those pyrrolizidine alkaloid levels.
This is in fact the case for the Butterbur extract used in the clinical studies above, Petadolex®. Tests have confirmed that commercial Petadolex® extracts have zero pyrrolizidine alkaloids. As such, most branded products with this butterbur extract have a “PA-free” statement on the label.
And yes, multiple studies have tested Petadolex® specifically for potential harm to the liver. The results have cleared the extract from any risk of harm to the liver.
Interestingly, of reports of supposed liver damage after taking butterbur extracts, researchers have discovered most of the patients were also taking significant amounts of NSAIDS. These are absolutely linked to liver damage, including Ibuprofen, Paracetamol and Naratriptan in multiple scientific studies.
This is not to say that PAs are not harmful in large doses. But we must note that even if a raw herb may contain some PAs, herbal medicines are typically consumed in such small doses that ingested PA levels will most likely be minimal. In addition, raw herbs and foods also contain significant amounts of antioxidants, which the research has showed are mostly protective against toxic effects of PA.
Bottom line, PA-free Butterbur extracts are proven to reduce migraines for both adults and children. And Butterbur extracts from reputable herbal suppliers, including Petadolex-makers labeled PA-free, are considered safe according to the scientific research.
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