4-methylthioamphetamine

Known as 4MT, 4-MTA, "Flatliners", 1-(4-methylthiophenyl)-2-aminopropane. CAS number 14116-06-04

This drug is a stimulant and strong serotonin releaser, similar to paramethoxyamphetamine but more dangerous, as it can cause pronounced hyperthermia which can result in organ failure and death. The subjective effects of 4MT are primarily a long-lasting stimulant, with little euphoria. 4MT is also a MAO-A inhibitor, which may explain its tendency to cause death, as MAOI drugs are not generally considered safe to use with stimulants or serotonin releasers, and 4MT fits into all three categories. 4MT was briefly sold on the black market as MDMA during the late 1990s, mainly in Holland and the USA, but proved unpopular due to its high risk of severe side effects and relative lack of positive MDMA-like euphoria.