On October 22, 2015, Oregon Attorney General Ellen Rosenblum sued GNC, alleging that it violated Oregon's Unlawful Trade Practices Act by knowingly selling products that contained the ingredients picamilon and beta-methlyphenylethylamine (BMPEA). The lawsuit alleges that both ingredients were "unapproved drugs that may not be lawfully sold in the United States as a dietary supplement."

GNC has said the lawsuit is without merit. In April 2015, the FDA sent warning letters to five companies (but not GNC) that listed BMPEA as a dietary ingredient in dietary supplements. GNC says it did not receive direct notice from FDA concerning BMPEA, but still stopped selling products containing the ingredient when it indirectly learned of FDA's stance. GNC also asserts it only learned of FDA's position on picamilon, created by synthetically combining niacin with gammaaminobutyric acid (GABA), when Rosenblum filed suit.

In a related development, Senator Claire McCaskill asked ten retailers to voluntarily pull picamilon supplements from store shelves. She had previously asked FDA to determine "whether picamilon is appropriate for sale, and to remove it from store shelves if it is not." FDA has not responded to her inquiry, prompting her request for voluntary removal by the retailers.