"More than half the states in the US now allow the use of marijuana for medical purposes, as well as at least 16 other countries. Yet of the hundreds of purported medical benefits, only three are concretely supported by scientific evidence: treating chronic pain, nausea after chemotherapy, and symptoms of multiple sclerosis. This is the conclusion of a new 400-page report from the US National Academies of Science, Engineering, and Medicine, which analyzed more than 10,000 scientific studies."