Where's the evidence?
Unlike some of the natural remedies currently marketed for hay fever, butterbur has scientific proof that it works. A number of studies-most of which were using a standardized extract of the herb known as Zeller's extract (ZE 339)-have found butterbur to be effective for relieving seasonal symptoms such as sneezing, itchy eyes and runny nose.
In one randomized controlled trial (RCT)-considered the 'gold-standard' for the scientific evalua-tion of treatments-186 hay-fever sufferers were given either a high or low dose of ZE 339, or a placebo, every day for two weeks.
The results showed that the butterbur extract was significantly better at improving symptoms than the placebo. What's more, the higher dose was more effective than the lower dose. Such 'dose-dependency' is generally taken to be a sign that the treatment truly does work (Arch Otolaryngol Head Neck Surg, 2004; 130: 1381-6).
In another RCT, 330 patients received either butterbur extract (one ZE 339 tablet three times a day), the antihistamine fexofenadine or a placebo for their hay fever. The butterbur preparation proved to be just as effective as the antihistamine, and both were better than the placebo (Phytother Res, 2005; 19: 530-7).
Similarly, when butterbur was pitted against the antihistamine cetirizine, they were both equally effective at improving symptoms. "Butterbur should be considered for treating seasonal allergic rhinitis [the medical term for hay fever] when the sedative effects of antihistamines need to be avoided", concluded the researchers (BMJ, 2002; 324: 144-6).
Although one small trial reported that butterbur had no significant effects (Ann Allergy Asthma Immunol, 2004; 93: 56-60), a review of the litera-ture on all butterbur research thus far concluded that there is "encouraging evidence" that the herb may be an effective hay-fever treatment. Nevertheless, the study highlighted the need for more independent studies, as three large trials had received financial support from a butterbur-extract manufac-turer (Ann Allergy Asthma Immunol, 2007; 99: 483-95).
Other medicinal effects
Butterbur appears to be useful for a number of other conditions as well as hay fever. Migraines, in particular, appear to respond well to the herb.
In one four-month American study, 245 patients who suffered from frequent migraines were randomly assigned to one of three groups: the first group took 75 mg of butterbur root extract twice daily; the second group took 50 mg of the extract twice daily; and the third group took a placebo. Neither the researchers nor the participants knew who was taking what (double-blind).
At the end of the study, the results showed that only the higher dose of butterbur was significantly superior-at one, two and three months-to the placebo in reducing the frequency of migraine attacks (Neurology, 2004; 63: 2240-4).
However, in a study aiming to assess the effectiveness of butterbur extract taken as a preventative (prophylactically), just 50 mg/day (one 25-mg capsule of butterbur root extract taken twice a day for 12 weeks) was enough to significantly reduce the frequency of migraines compared with a placebo-with no reports of any adverse events (Altern Med Rev, 2001; 6: 303-10).
There's also evidence that butterbur may be useful against asthma attacks. In one preliminary trial, 64 adults and 16 children/ adolescents were treated with an extract of the herb (Petadolex) in addition to their usual asthma medication for two to four months. Not only did the number, duration and severity of attacks decrease during the therapy, but the forced expiratory volume increased (a sign of better lung function) and all the other assessed symptoms improved, too. Moreover, more than 40 per cent of the patients were able to reduce their use of asthma medications by the end of the study (Altern Med Rev, 2004; 9: 54-62).
Some studies hint that butterbur might also be beneficial for gastrointestinal disorders (such as stomach ulcers) and bladder problems (Altern Med Rev, 2001; 6: 207-9). However, the evidence so far suggests that it's not effective against allergic skin reactions such as eczema (Ann Allergy Asthma Immunol, 2004; 92: 250-4).
Dosage and safety
The usual dosage of butterbur is 50-75 mg twice daily of a stand-ardized extract of the herb (usually containing a minimum of 7.5 mg
of petasin and isopetasin, the main active ingredients). In general, this is well tolerated, with only mild gastrointestinal complaints (such as burping) being the most com-monly reported side-effects (Adv Ther, 2006; 23: 373-84).
However, butterbur is known to contain toxic compounds called 'pyrrolizidine alkaloids'. These may be harmful to the liver and possibly carcinogenic; happily, alkaloid-free preparations are available.
At this time-and until further safety testing has been carried out-it's advisable that butterbur not be used by pregnant or nursing women, young children, and those with severe kidney or liver disease. If in doubt, it's best to consult a qualified health practitioner.
WDDTY VOL 21 NO 2