In short: The main effects of Molly/Ecstasy last around 3 hours, and minor effects last around 7 hours - assuming your substance contains pure MDMA. If you’re a new user taking MDMA on an empty or mostly empty stomach, you should notice the MDMA kick in around 1 hour after ingestion - experienced users who are familiar with the effects may notice it kick in after as little as 30 minutes.