Side Effects & Safety When taken by mouth: Pyrrolizidine alkaloid (PA)-free butterbur products are POSSIBLY SAFE when taken by mouth appropriately for up to 16 weeks. PA-free butterbur is generally well tolerated. It can cause belching, headache, itchy eyes, diarrhea, upset stomach, fatigue, and drowsiness. But it seems to cause less drowsiness and fatigue than cetirizine (Zyrtec) when taken for allergies. Liver injury occurs rarely.



Some butterbur products may contain PAs, and that's the major safety concern. PAs can damage the liver, lungs, and blood circulation, and possibly cause cancer. Butterbur products that contain PAs are LIKELY UNSAFE. Do not use butterbur products unless they are certified and labeled as free of PAs.



When applied to the skin: Butterbur products that contain PAs are LIKELY UNSAFE when applied to broken skin. Broken skin allows chemicals to be absorbed into the body. Do not use butterbur products unless they are certified and labeled as free of PAs. There isn't enough reliable information to know if butterbur is safe to use on unbroken skin or what the side effects might be. Special Precautions & Warnings: Children: Pyrrolizidine alkaloid (PA)-free butterbur is POSSIBLY SAFE when taken by mouth appropriately. There is some evidence that a specific PA-free butterbur rhizome extract (Petadolex, Weber & Weber, GmbH & Co, Germany) can be safely used in children aged 6-17 years for up to 4 months.



Pregnancy and breast-feeding: Taking butterbur by mouth is LIKELY UNSAFE while pregnant or breast-feeding. Butterbur preparations containing pyrrolizidine alkaloids (PAs) might cause birth defects and liver damage. Not enough is known about the safety of using butterbur products that do not contain PAs during pregnancy or breast-feeding. Don't use it.



Allergy to ragweed and related plants: Butterbur may cause an allergic reaction in people who are sensitive to the Asteraceae/Compositae family. Members of this family include ragweed, chrysanthemums, marigolds, daisies, and many others. If you have allergies, be sure to check with your healthcare provider before taking butterbur.



Liver disease: There is some concern that butterbur might make liver disease worse. Don't take it.



