Federal health officials are cracking down on bogus pills and supplements that their makers claim will cure or prevent sexually transmitted diseases like HIV, herpes and genital warts. The Food and Drug Administration announced Tuesday that it has sent warning letters to a dozen companies selling non-prescription products with names like Medavir, Herpaflor and C-Cure. The agency said none of the products have been proven to treat any disease.

“These products are dangerous because they are targeted to patients with serious conditions, where treatment options proven to be safe and effective are available,” said Deborah Autor, FDA’s director of drug compliance, in a statement.