The Food and Drug Administration chastised two companies for marketing the herb kratom as a treatment for opioid withdrawal and other ailments, as frustration mounts that a broader crackdown isn’t doing enough.

The FDA on Tuesday warned vendors Chillin Mix Kratom and Mita Distributing for claiming the herbal supplement kratom can help with opioid withdrawal and treat other ailments like diabetes and obesity. The warnings are the latest targeting retailers making false claims about the supplement that people primarily use for pain relief.