Van Gogh was very keen on his pipe, and was always smoking, whether he was painting or not. He also regularly drank alcohol, but probably not while he was working. He drank more than he should in Paris – one of the reasons that he fled the city in 1888.
In Arles, he wrote in a letter to Theo that developing a painting is exacting work, ‘[…] where you have to think of a thousand things at the same time in a single half hour. Afterwards — the only thing that comforts and distracts — in my case — […] is to stun oneself by taking a stiff drink or smoking very heavily.’