11 side effects of using marijuana. For all those stoners who say it won't kill you or cause health problems, well here you go! You can excuse or deny marijuana being a drug, and you can say that it won't kill you, but in 17 years of smoking it, I now have all of these problems. So how does it not affect your health again? Did you know that not one drug on this earth raises your heart rate faster than the first 30 minutes after taking marijuana? After that its harmful affects subside. Truth. But the reality is, anything you inhale that is the smoke of something burning will damage your lungs, heart, and brain. Instantly.