Be fair, there are gross bits, but they're all in there for very good reasons. Bits of it are way stylised and go somewhat out of their way to be disgusting, but that's the point. They are there because they symbolise something and add to the visceral impact of the film.
Amusingly enough, the film had to be cut for American release because they thought some bits of it were too disgusting. Which bits? Kelly McDonald straddling Ewan McGregor, and the shot of the needle being injected into the skin before he overdoses. Like yeah, those are the most vile bits of the film.