I never said it wouldnt - although it's never done anything like that to me, i might just be lucky, but im smoking 14g a day here and i'm not getting any problems. When i was smoking cigs i'd have chest infections all the bloody time - and as soon as i quit them i've been fine so i know it's not the weed [THC also has anti-biotic properties so it can help chest infections]

Still though, apart from a cough your not looking at serious health risks.