2006-08-14
Mayo Clinic

Looking for an herbal remedy for your allergies? Some research suggests that the herbal supplement butterbur may relieve allergy symptoms. But there are possible side effects of using butterbur. Before you try butterbur for allergies, know what to look for and how to tell if it's safe for you.

What is butterbur?

Butterbur (Petasites hybridus) is a large-leafed, shrub-like plant native to Europe. Extracts from the roots, leaves and stem of the butterbur plant have been used to treat migraine headaches, stomach ulcers, infections and coughs, as well as allergies and asthma. During the 14th century, butterbur was used to treat plague and fever.

Butterbur has anti-inflammatory effects that decrease histamine and leukotrienes (chemicals involved in allergic reactions). However, butterbur also contains substances that can be toxic to your liver and may cause cancer. Some butterbur products are processed to reduce the amount of these toxins.

Butterbur is also commonly known as:

• Butterfly Dock

• Bog Rhubarb

• Butter-Dock

• Blatterdock

• Exwort

Butterbur is most commonly taken as tablets (Petadolex, Petaforce, Tesalin). It's also available in teas, extracts, and capsules containing raw herbs. You can buy butterbur as a tablet or as part of a product that contains a mixture of herbs.

Does it work?

It is thought that butterbur works similarly to antihistamines by blocking the action of the inflammatory chemical histamine, which is released by your immune system during an allergic reaction. A 2004 study published in "Clinical & Experimental Allergy" reported butterbur to be as effective as the prescription drug fexofenadine (Allegra) in treating symptoms of hay fever. Another study published in the June 2005 issue of "Phytotherapy Research" showed similar results with the butterbur product Ze 339. This study showed butterbur worked as well as the prescription drug cetirizine (Zyrtec) for hay fever symptoms. In addition, butterbur tends to cause less drowsiness, a common side effect of antihistamine medications.

While results of studies on butterbur seem positive, the quality of some studies has been a matter of some debate. It is unclear whether the results are valid. In addition, butterbur studies have been limited to only a few weeks. Other clinical studies have shown no benefit from taking butterbur for allergies. No studies have been done to determine the long-term safety and effectiveness of butterbur.

Is it safe?

If you suffer from allergies, butterbur may look promising, however, more research is needed to be sure its safe to use long term. Studies have yet to determine how safe it is to use butterbur for longer than two weeks.

Side effects
Possible side effects of oral butterbur include:

• Headache

• Itchy eyes

• Fatigue

• Drowsiness

• Indigestion

• Nausea

• Vomiting

• Diarrhea

• Constipation

Risks

Risks associated with butterbur include:

• Allergic reaction. If you're allergic to ragweed, butterbur may actually worsen your allergy symptoms. Butterbur is related to the ragweed family of plants and may cause an allergic reaction. Don't use butterbur if you're allergic to ragweed, marigolds, daisies or chrysanthemums.

• Liver and kidney damage. Butterbur contains chemicals called pyrrolizidine alkaloids (PAs) that are toxic to your liver and kidneys. Long-term use of butterbur may increase your risk of liver and kidney damage. Young children, pregnant or nursing women, or people with liver or kidney disease shouldn't use butterbur.

• Cancer. Pyrrolizidine alkaloids (PAs), the toxic chemicals in butterbur, may also have cancer-causing effects.

What should I do if I want to try butterbur?

If you want to try butterbur to help your allergy symptoms, talk with your doctor first. He or she can help determine if butterbur is safe for you and can discuss more treatment options. If your doctor says it's OK for you to try butterbur, follow these tips:

• Look for standardized butterbur supplements. A butterbur supplement labeled standardized has a consistent measured amount of the active ingredient. The U.S. Pharmacopeia's "USP Dietary Supplement Verified" seal on an herbal supplement is another label to look for when buying supplements.

• Make sure it's PA-free. Butterbur that's PA-free has had the pyrrolizidine alkaloids — potentially harmful toxins — removed during processing. Only use a butterbur supplement that's labeled PA-free.

• Follow dosage instructions. Only take as much butterbur as directed — taking more could lead to increased complications and serious side effects.

• Record your use. Keep track of how much and how often you use butterbur. This will help you measure any positive outcomes or adverse side effects.

• Call your doctor if problems occur. If you experience any adverse side effects from taking butterbur, stop taking the supplement immediately and call your doctor.

The Food and Drug Administration, the federal agency responsible for overseeing the safety of U.S. food and drug products, doesn't have the authority to approve herbal supplements. Herbal supplements may have harmful effects — some can even make your symptoms worse.

Talk with your doctor before using an herbal supplement. Just because herbal remedies are considered "natural" doesn't mean they're harmless. Herbal supplements can cause severe reactions with prescription and over-the-counter medications you're taking and can complicate other health conditions you may have. Be sure to tell your doctor about any herbal remedies you use.