Microdosing psychedelics is the practice of taking very low doses of psychedelic substances (e.g. LSD, psilocybin). Psychedelic microdosing has recently been featured in numerous popular-media reports yet no scientific studies have been published on this topic. At present only anecdotes regarding the effects of microdosing are discussed and these have not been described in the scientific literature. To address these literature gaps we ran the first pre-registered scientific study on microdosing psychedelics by investigating the practices of online communities already engaging in this activity. This pre-registered online study collected 1034 benefits and 791 drawbacks drawn from 577 participants. These data were subjected to classic Grounded Theory analysis and a number of highly relevant conceptual groupings of benefits and drawbacks emerged. By discussing these groupings and suggesting psychometric measures intended to assess these outcomes this lecture will provide researchers with tangible suggestions for incorporating relevant measures into their psychedelic studies. We will also make recommendations that inform the non-academic community about the potential outcomes of microdosing with added focus on harm-reduction. This research informs both the individuals already microdosing and the scientific community intending to study microdosing and psychedelic outcomes in the future.