The conclusion of Hollister's review of pharmacological research on marijuana states that:

Compared with other licit social drugs such as alcohol, tobacco, and caffeine, marijuana does not pose greater risks. One would wonder, however, if society were given a choice based on current knowledge, whether these drugs would have been granted their present status of acceptance. Marijuana may prove to have greater therapeutic potential than these other social drugs, but many questions still need to be answered." Hollister, L.E.(1986), "Health Aspects of Cannabis", Pharmacological Reviews, 38:1,1-20. pg. 17.