‘Dei Machsoro’ (this is not translated as luxuries). This probably does not include feeding an addiction
It does include luxuries, actually, if he’s accustomed to them. I’m not sure why it shouldn’t include an addiction.
A doctor told someone I know that one cigarette a day will not harm him.
I wonder if for this reason, there’s no lifnei iver on giving a cigarette or match. Even if we assume it’s assur to smoke, it’s the totality of the habit/lifestyle which is dangerous and assur, not any individual cigarette.