I smoke a decent amout and a pack of ciggerates a day all for about a year and noticed nothing...although sometimes (only 3 times in my life) when I smoke alot of realllly goood bud, to many cigs at once, eat like all hell, and do it all in a hot tub or pool or something like that I have gotten sick and have thrown up...I only threw up 3 times but have gotten sick more but if i take off my shirt and sit infront of my fan it usally passes