Assuming you mean snake venom…
Very expensive hydration occurs. The primary difference between a poison and venom is that a venom must be injected in order to be toxic. Snake venom is generally harmless if you eat it – so long as you don’t have any open wounds in your mouth or throat, you’ll just digest it and be fine.
Of course, you did specify ‘poison’. There only only a couple of actually poisonous snakes in the world. If you were to… I guess, grind them up and dilute them with a lot of water… well, then it would depend on the dose. If you didn’t consume very much of the poison at once, you’d be fine. The dose makes the poison, after all. If you did consume a lot, you’d be in a bit of trouble. The tiger keelback, for example, produces bufadienolides, which is a cardiac glycoside. It’s a type of neurotoxin, and can stop your heart.