Supplements that contain tianeptine, a dangerous substance that can cause adverse health effects, have recently been illegally marketed as treatments for depression, opioid use disorder, pain, and anxiety. The federal Food and Drug Administration has issued warnings to two companies for making unproven, illegal claims about supplements that contain tianeptine. Supplement companies are forbidden from marketing their products as a cure for anything since they are not medications. The FDA has not approved tianeptine for any use. The dangerous additive should not be present in any supplements.