4,4'-Dimethylaminorex (abbreviated as 4,4'-DMAR), sometimes referred to by the street name "Serotoni", is a psychostimulant and entactogen designer drug related to aminorex, 4-methylaminorex, and pemoline.

4,4'-DMAR had been linked to at least 31 deaths in Hungary, Poland, and the UK by February 2014, mostly when consumed in combination with other drugs.

[5] Nineteen deaths linked to 4,4'-DMAR were reported in Northern Ireland in the same time period.

[3][7] It also interacts with the vesicular monoamine transporter 2 (VMAT2) with similar potency as MDMA.

[22] Sweden's public health agency suggested to classify 4,4'-DMAR as hazardous substance on November 10, 2014.