The first comparison to make is in the category of physical harm, in which both substances pose the very low risk of physical harm to the user as they both requ

The first comparison to make is in the category of physical harm, in which both substances pose the very low risk of physical harm to the user as they both require an insane dose (>100x normal dose) to pose an immediate medical concern. However, if marijuana is smoked (like anything else smoked) it is not good for the health of the user over the long term. In this category, LSD is the clear winner in risk of harm to the user. The other category is, of course, harm to the user's mental health. In my opinion, dependence is a huge part of this category and cannabis, while not particularly addictive, is definitely more addictive and can produce minor to moderate physical withdrawal effects. LSD seems to be the antithesis of addictive. There's also the social harm category that I can't speak to, but the UK Centre for Crime and Justice Studies sponsored a study [0][1] in 2010 that also takes this into account. [0] https://www.ncbi.nlm.nih.gov/pubmed/21036393 https://www.ncbi.nlm.nih.gov/pubmed/21036393 [1] https://www.economist.com/graphic-detail/2010/11/02/scoring-drugs https://www.economist.com/graphic-detail/2010/11/02/scoring-...