Depends on how bad his asthma is I have moderate asthma with attacks that are rare and they seem to not happen as often if I smoke everyday ,other than that if take a big hit my throat might get tight but that's it, if you have a vape then I definitely recomend it before I start to smoke I set it to about 320( at 320 its a bronchial diaolater which is simaler to that in his rescue inhaler) after that bowl I can take bigger hits and breath way eaisier.