Generally, no. Not even comparable to tobacco. Being a long time, once in a while, responsible drug user who smokes cannabis infrequently but smokes cigarettes every day, I can tell you that throughout my drug-taking "career" I have had almost no long-term effects (though I don't recommend using drugs recreationally), but then again I use infrequently. However, with cigarettes, I have permenantly bad lungs- I can barely run- whereas when I used to smoke marijuana every day (before I began consuming tobacco) I still had good lung capacity. All of that B.S. that the anti-drug campaigns (the ones founded by soccer moms and former drug addicts) tell you about long-term mental health problems is mostly untrue. The only people who will be changed long-term from using cannabis were those who already had a risk of mental problems (anxiety, etc.) Also the myth that cannabis destroys brain cells is untrue. No medical tests have shown any proof that marijuana kills brain cells, and marijuana is not a neurotoxin, as some even legally prescribed drugs are. Actually, in some cases, it is a neuroprotectant.