Praise be to Allah.
Sheikh Ibn Uthaymin (may Allah have mercy on him) said:
“I think that this is a view for which there is no basis. Rather smoking is a kind of drinking; in Arabic they say that one “drinks” a cigarette. Moreover, there is no doubt that smoking reaches the stomach and the inside of the body, and everything that reaches the stomach and the inside of the body invalidates the fast , whether it is beneficial or harmful, even if a person were to swallow a bead from the masbahah, or a piece of iron, or anything else, it invalidates the fast.
So it is not essential that the thing that invalidates the fast, or that is eaten or drunk, should be nourishing or beneficial. Everything that reaches the stomach is regarded as food or drink. They believe – indeed they know – that this is a kind of drink, and if anyone says this then he is being arrogant.
Moreover, I think that the month of Ramadan is an opportunity for the one who is sincerely resolved and wants to give up this foul, harmful habit of smoking. I think that it is an opportunity because he is going to abstain from it throughout the day in Ramadan, and at night he can distract himself from it by means of the food and drink that Allah has permitted to him, and by frequenting the mosques and attending gatherings of righteous people, and he can keep away from those who have this habit. If he abstains from it throughout the month, then that will be a great help to him in giving it up for the rest of his life. This is an opportunity which smokers should not miss.” (Majmu` Fatawa Ibn ‘Uthaymin, Fatawa Al-Siyam, pp. 203-204)
And Allah knows best.