4-Fluoromethamphetamine (4-FMA) is a stimulant drug related to methamphetamine and 4-fluoroamphetamine. It has been reported to be sold as a designer drug, but little is known about its pharmacology or toxicology. Anecdotal user reports however mention a high risk of physical dependence and serious withdrawal symptoms, such as fever and a tendency for dissociation, which last about a week. It was first detected from legal highs sold in Japan in 2006 and became illegal to sell or to possess for the purpose of distribution (although not to simply possess for personal use) in Japan in 2008. It was initially reported to be contained as an ingredient in some of the range of party pills sold internationally by the Israeli company Neorganics from around 2006 onwards, but this was later shown to be incorrect and this ingredient was eventually identified as the closely related compound 2-fluoromethamphetamine.
User reports describe the effects of 4-FMA as having characteristics of both traditional stimulants like amphetamine and entactogens like MDMA. Its effects have been described as subjectively lying between 4-FA and 2-FMA. It has been reported to be more likely to produce side effects like headaches and cardiovascular effects than similar substances.
Very little is known about the pharmacological properties, metabolism, and toxicity of 4-FMA. 4-FMA use may produce dependence and abuse as well as damage to the brain and other organs. It is highly advised to use harm reduction practices if using this substance.