You can drink it, just like injectable Winstrol or Anavar; but the injectables avoid the first pass at the liver and therefore allow more of the substance to work its magic before being destroyed. The effect on the liver is the same; whether oral or injectable it is going to be metabolized by the liver, just because it doesn't go through your stomach into the liver (first pass) doesn't mean it doesn't end up there - so a liver protectant or whatever might be a good idea. I did not find my experience with Injectable Dbol to be very painful, the first shot or two in the muscles did hurt more than usual, but I got use to it or it went away; it's not really the shot that hurts anyway, rather the next day soreness - which I find one's muscles get use to and the pain, if any, goes away with use.
I prefer the linjectables myself, I feel I get a better anabolic response from them. The liquids whether injectable or not, I feel 'hit' your system faster and offer that benefit - If one were to use just pre-workout for instance. Also consider than in my opinion, especially with Dbol is that the injectable allows one to use around half of their usual dose for the same effect.
