3-Methylmethamphetamine (3-MMA or 3-Me-MA), also known as metaphedrine, is an amphetamine derivative which has been sold as a designer drug, first encountered online in 2020 and reported in Sweden in 2021. It is a potent monoamine reuptake inhibitor and is thought to have psychostimulant effects. The drug was not active as a serotonin 5-HT<sub>2A</sub> receptor agonist.