Several companies currently selling CBD-based medical products have received warning letters from the FDA accusing them of advertising their products as effective cancer treatments without scientific evidence to back them up, reports cannabis activist Tom Angell. In a press release accompanying these letters, the FDA accuses the companies of “illegally selling products online that claim to prevent, diagnose, treat or cure cancer without evidence to support these outcomes.”

“Substances that contain components of marijuana will be treated like any other products that make unproven claims to shrink cancer tumors," said FDA Commissioner Scott Gottlieb, M.D. in the statement. “We don’t let companies market products that deliberately prey on sick people with baseless claims that their substance can shrink or cure cancer, and we’re not going to look the other way on enforcing these principles when it comes to marijuana-containing products."

Four companies received letters from the FDA on October 31st: Stanley Brothers Social Enterprises LLC, which does business as CW Botanicals and CW Hemp; Green Roads of Florida LLC; Natural Alchemist (Alurent Inc.); and That’s Natural! Marketing & Consulting. In the letters, the agency flagged several claims advertised by these companies, such as: “Combats tumor and cancer cells” “CBD makes cancer cells commit ‘suicide’ without killing other cells;” and “Non-psychoactive cannabinoids like CBD (cannabidiol) may be effective in treating tumors from cancer – including breast cancer.”

The FDA alleges that these claims violate the Federal Food, Drug and Cosmetic Act, and also put patients at risk because “these products have not been proven to be safe or effective.” The agency has also emphasized that CBD cannot be considered a dietary supplement because it is already being investigated by the agency as a potential new medication in the U.S. Last month, London-based GW Pharmaceuticals and its stateside subsidiary, Greenwich Biosciences, submitted a New Drug Application to the FDA for Epidiolex, a CBD drug created to treat childhood epilepsy disorders. The company is hopeful that the drug will be approved for launch next year.