Herbal products can cause serious harm through toxic ingredients, misidentification, or mislabeling.

A peer-reviewed review describes kidney failure, kidney scarring, and increased urothelial-cancer risk linked to products containing aristolochic acids. In one weight-loss episode, a similar name led to the wrong plant being supplied; more than 100 women suffered serious adverse events. These findings do not prove that herbal medicine as a whole is useless, nor do they support murder theories. They do show why product identity, dose, interactions, and clinical evidence matter.