Pyrrolizidine alkaloids (PAs) are compounds that naturally occur in many types of plants, and some PAs can be toxic — particularly to the liver. PAs have also been found in herbs that don't naturally contain them but are accidentally harvested with plants, such as weeds, that do.
PAs are not allowed in dietary supplements in the U.S. and those that contain them are considered adulterated. The FDA has noted that products in the U.S. may still contain herbal ingredients that naturally contain PAs provided the products have been processed and confirmed through validated analytical methods to be PA-free. However, there currently do not appear to be any such validated methods, and, even if there were, this would not have to be furnished to the FDA to market the products. Sign in for more details, including herbal ingredients that can contain PAs and the symptoms of PA toxicity.