It has psychotropic effects, causing an increased risk of accident. It has a small risk of addiction (something like 10%), but it does exist. It can exacerbate anxiety, depression and schizophrenia. It increases the risk of heart attack. Marijuana smoke has more carcinogens than cigarettes, and it causes respiratory problems at about the same rate of cigarettes. It impacts a person’s cognitive and social abilities, making it harder to hold a job. And remember, we don’t even need “medical” marijuana because we are able to produce the associated chemicals (but you don’t get a high from those medications). I’m all for legalization, but I’m tired of people lying about the adverse health risks of marijuana.