A potentially dangerous supplement dubbed “gas station heroin” is being sold at convenience stores and online and getting users hooked. The pills contain tianeptine and are sold under names including “Za Za Red” and “Tianna.” They are hawked as a dietary supplement that helps to improve brain function and to treat anxiety and depression, according to a report by NewsNation. But they can lead to an opioid-like high, which is leaving some users addicted, experts told the outlet — and the FDA says the products are linked to overdoses and deaths. Poison control centers have seen a surge in tianeptine-related...