The Federal Trade Commission said Tuesday it sent warning letters to three unidentified companies, that it is illegal to advertise that their products infused with CBD (cannabidiol) can act as treatments for diseases such as cancer, Alzheimer’s and multiple sclerosis. The FTC noted the claims were made without “competent and reliable scientific evidence” to support the claims. In April, the Food and Drug Administration had warned three companies–Relievus, Nutra Pure and PotNetwork Holdings–to stop making “unsubstantiated advertising claims” about their products’ abilities to treat or cure cancer and Alzheimer’s. On Tuesday, the FTC said it selling CBD products without substantiation could result in legal action, that could lead to an injunction or an order to return money to customers. “The letters instruct the companies to notify the FTC within 15 days of the specific actions they have taken to address the agency’s concern,” the FTC said.