If you want to know about the safety of nutritional supplements, the best place to go is the Natural Products Association. They are THE organization that polices the supplement industry. If a product has their GMP certification, then it can be trusted to exceed the manufacturing and processing safety standards required by DSHEA ("de-shay"😉, the Dietary and Supplement Health Education Act. When my family ran our health food store, we would only stock products with GMP certification because their labs were pharmaceutical grade or better.
Petadolex is considered generally safe when used as directed. It is free of harmful pyrrolizidine alkaloids. The controversy is a political one. You wouldn't believe how political the supplement industry can get. When the purification process was changed (to remove even more PAs), the German regulatory board required the company to undergo expensive safety testing to prove what everyone already knew -- that Butterbur with the PAs removed was safe for human use. The decision to decline this testing was a business decision and in no way affected the quality of the product. The company had already invested in development and safety testing here in the U.S. but Germany wouldn't accept those results.
When you consider the toxicity of Depakote, Lithium, and other pharmaceuticals (even Tylenol!) used to treat migraine, Petadolex begins to look tame. I would still want my doctor to know that I was taking it. I would also ask for baseline liver enzyme tests and periodic monitoring just in (rare) case toxicity occurs. Considering all the dangerous medicines we use routinely to treat migraine, all this fuss and worry about Petadolex seems misplaced.
Yes, I am biased in favor of nutritional supplements and desperately wish one of them had been effective for me. If it would do any good, I'd be taking Butterbur instead of Verapamil (hard on my heart), Amitryptiline (gives me dry mouth and weird dreams), Amerge (also hard on my heart), and Botox (awfully expensive!).
Tammy (writing as a fan of supplements, my opinions are not necessarily those of Migraine.com or other Patient Advocates.)