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Open Clinical Trial Shows Potential for Butterbur Root Extract in Asthma Treatment
Open Clinical Trial Shows Potential for Butterbur Root Extract in Asthma Treatment

Reviewed: Danesch U. Petasites hybridus (Butterbur root) extract in the treatment of asthma—an open trial. Altern Med Rev. 2004;9(1):54-62.

Asthma is a chronic inflammatory disorder of the airways. Asthma treatment typically consists of a control medication to provide long-term therapy and a relief medication to provide quick-relief therapy. The therapies have the potential to cause adverse systemic side effects. Butterbur (Petasites hybridus [L.] P. Gaertn. et al, Asteraceae) root powder has been shown to improve lung function in patients with chronic asthma and chronic bronchitis (a condition of excessive mucus and cough). The active compounds are thought to be petasins, a group of sesquiterpenes. The purpose of this study was to assess the efficacy and safety of Petadolex® (Weber & Weber International GmbH & Co. KG, Germany), a standardized extract of butterbur root, in patients with asthma. Unprocessed butterbur root contains pyrrolizidine alkaloids (PAs), which are known hepatotoxins; however, Petadolex has had all the PAs removed and exceeds specifications for maximum allowable levels of PAs as initially established in the German Commission E monograph of 19901 and then subsequently revised to a lower level by the German Federal Institute for Drugs and Medical Devices (BfArM) in 1992.2

Eighty patients (aged 6-85 years) with mild or moderate asthma participated. The study took place at multiple locations, i.e., a clinic and the offices of 11 private practice physicians in Germany. The open label study consisted of a 2-week run-in phase and a 2-4 month treatment phase. The dosage for adults was 50 mg Petadolex 3 times/day (total 150 mg/day); for children the dosage was 50-150 mg daily, depending on age. Patients were permitted to continue with their regular asthma medications. Patients recorded symptoms in a diary and were examined by a physician 4 and 8 weeks after consuming Petadolex.

Lung function tests were performed to assess and monitor airflow obstruction. Approximately two-thirds of the patients had a clinically significant increase in airflow after 2 months of Petadolex treatment. The results show that compared to baseline there was a continual decrease in the number, duration, and severity of asthma attacks with Petadolex treatment from week 1 to week 16. However, the number of asthma attacks showed an increase in the last study month compared to baseline. This anomaly is mainly due to one child who experienced 34 attacks during a school camp visit. Adding these 34 attacks to the totals of all other patients confounded those data since at the very end only a few patients were left in the study.

After 8 weeks patients were permitted to continue the treatment with Petadolex if they desired. The results show that the asthma symptoms (coughing, difficulty breathing, chest tightness, wheezing, etc.) continued to improve in patients who continued to take Petadolex (by the end of the trial 32ontinued on the treatment), with 95% of these patients reporting that Petadolex was effective in treating their asthma. Of the patients taking the conventional pharmaceutical asthma medications in addition to Petadolex, 43% of those on corticosteroids and 48% of those on beta-agonists reduced the amount of their use of these drugs while they were consuming Petadolex. The number of patients discontinuing Petadolex increased towards the end of the study, culminating by the 16th week with a maximum of 68% of patients voluntarily discontinuing Petadolex.

Petadolex was well tolerated. Eleven adverse events were experienced by 7 patients. The authors believe that, according to ratings by physicians, adverse events reported were probably not related to treatment with Petadolex.

The authors conclude that 150 mg per day of a butterbur extract is an effective and safe asthma treatment for children and adults. However, this study has several weaknesses. First, nearly 80% of the patients had mild asthma. Therefore, the question remains as to whether Petadolex would be effective in patients with moderate or severe asthma. It was not effective in one child who had an exceptionally high number (34) of asthma attacks while attending camp during hay fever season. Second, there are many different triggers for an asthma attack; for example, allergies, smoke, and exercise. The authors did not indicate what the triggers were for this patient population. Perhaps the patients who improved were not exposed to their asthma trigger. Third, there was no control group, so there is no way to know if some of the observed improvement may have been due to a placebo effect. This is the first clinical trial on patients with asthma using a well-characterized butterbur extract in the MEDLINE-indexed literature. The study needs to be repeated with a better design before firm conclusions can be made.

—Heather S. Oliff, PhD, and Mark Blumenthal


1. Blumenthal M, Busse WR, Goldberg A, Gruenwald J, Hall T, Riggins CW, Rister RS, eds. Klein S, Rister RS, trans. The Complete German Commission E Monographs—Therapeutic Guide to Herbal Medicines. Austin, TX: American Botanical Council; Boston: Integrative Medicine Communication; 1998.

2. German Federal Institute for Drugs and Medical Devices (BfArM). Köln, Germany: Government Bulletin [in German]. Bundesanzeiger Nr 111, vom 17.06.1992.