But concerns remain about the safety of unregulated products containing the plant extract sold in the United States.
The Swiss study was the largest ever to examine butterbur for the treatment of allergies. A total of 330 participants receive either the butterbur-extract product Ze339, high doses of the antihistamine Allegra, or placebo.
Swiss herbal medicine manufacturer Zeller AG, which markets Ze339, sponsored the research. The product is not sold in the United States, but other butterbur-extract products are.
Researcher Andreas Schapowal, MD, PhD, tells WebMD that this and other studies conducted by his research team show that the herbal product is both safe and effective. He adds that because it is also nonsedating, it could be a good choice for people who experience drowsiness when taking certain antihistamines.
Butterbur Used for Centuries
Butterbur (also known as blatterdock, flapperdock, or butterfly doc) is a plant found throughout Europe and Asia and parts of North America. It has been used in herbal remedies for centuries and in commercial medicines in Europe for several decades.
In nature, the plant does contain chemicals that are considered toxins and may be carcinogenic. There have been isolated reports of serious liver problems occurring in people who took butterbur preparations containing high levels of these chemicals.
Schapowal says the product he tested is safe because it is derived exclusively from the heart-shaped leaves of the butterbur plant and not the root, as some other preparations are. Plants are also especially cultivated to make the herbal product.
In the newly published study, hay fever patients being treated at 11 centers throughout Switzerland and Germany received either Ze339 three times a day (totaling 8 milligrams), a single-daily 180-milligram tablet of Allegra, or a placebo.
The researchers reported that both active treatments were equally effective and more effective than placebo for relieving hay fever symptoms such as sneezing, nasal congestion, and itchy eyes and/or nose. Both active treatments were also well tolerated. The findings were reported in the June issue of the journal Phytotherapy Research.
Safety of Other Products Questioned
Schapowal says he's confident that the product his group tested is safe. But he is less sure about unregulated herbal products containing butterbur that are sold in the U.S.
"I wouldn't take them," he says. "Many of these products are derived from the root of the plant and there is no controlled cultivation. They cannot be considered safe."
Allergist Brian Smart, MD, says that a "natural" treatment for allergies and asthma would be welcome. But he adds that none of the alternative products widely used for this purpose in the U.S. have been adequately tested.
Smart is a spokesman for the American Academy of Allergy, Asthma, and Immunology, which reported in 2003 that 17% of Americans seeking treatment for allergies had tried complementary and alternative medications. Butterbur, ephedra, grape seed extract, and thymus extract are some of the most widely used alternative therapies for hay fever and allergy.
The report concluded that none of the alternative products have been proven both safe and effective.
"As an allergist I always welcome the possibility of new therapies," Smart tells WebMD. "But my concern is that these products are not regulated, so you really don't know what you are getting. Even though a so-called natural product sounds safer, it may not be."