Can marijuana cause asthma after many years of marijuana use can it cause you to have ashthma after never having any symptoms before?

No that is impossible. Weed does not cause any problems with lungs. ^^^^^^^ You're stupid. I would visit this website: http://www.erowid.org/plants/cannabis/cannabis_faq1.shtml It has everything you need to know about weed. !!update on that statement, smoking anything is bad for your lungs, but other than that no, you wont get asthma from weed. Maybe smoker's cough, no asthma.