DOI or 2,5-dimethoxy-4-iodoamphetamine is a psychedelic drug and a substituted amphetamine of the phenethylamine family. Despite being a substituted amphetamine it is not a stimulant. DOI has a stereocenter and R-(-)-DOI is the more active stereoisomer. In neuroscience research, [125I]-R-(-)-DOI is used as a radioligand and indicator of the presence of 5-HT2A serotonin receptors. When ingested recreationally, DOI is active at a dosage of 1.5 - 3.0mg (orally) and has a duration of 16 - 30 hours (approximately twice as long as LSD). DOI's effects have been compared to LSD, although there are differences that experienced users can distinguish. Besides the longer duration, the trip tends to be more energetic than an LSD trip, with more body load and a different subjective visual experience. The after effects include residual stimulation and difficulty sleeping, which, depending on the dose, may persist for days. It is often sold as a substitute for LSD, or even sold falsely as LSD, which may be dangerous because DOI does not have the same established safety profile as LSD. Unlike LSD, the psychedelic amphetamines (including DOI) can have harmful and potentially fatal physical effects in overdose. Although there have been no known deaths due to DOI ingestion, it is relatively new on the recreational scene so long-term effects are not known.