nothing
it can give you brain damage.
Alcohol by far as it does damage to your body and causes addiction.
The only thing is lung damage from the smoke but if you eat it its completely harmless
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brain damage
no marijuana is good for you
why are you asking?
There is some damage to the lungs caused by marijuana smoke inhalation. (However, note that marijuana does not necessarily have to be smoked, it can also be brewed as tea.) Interestingly, marijuana smoke has not been found to be carcinogenic, unlike cigarette smoke. However, marijuana smoke is still an irritant to the lungs and can contribute to the eventual development of emphysema.
No!
Marijuana really isn't bad; the only reason its still illegal is because the government would have a hard time taxing the substance, as marijuana is simple to grow with the correct equipment. The only harmful effect marijuana has on your body is SLIGHT lung damage. However, most marijuana smokers do not smoke as much as cigarette smokers to cause lung cancer.
Technically no, because marijuana does not damage brains in the first place. http://www.webmd.com/mental-health/news/20030701/heavy-marijuana-use-doesnt-damage-brain