I think the OP's original question has been answered, though he could have figured it out just from a google search. You can overdose on anything no matter how you take it if you do enough. As far as the pain from overdose thing, the only pain I ever experienced is coming out of the blackout. Incredible headache, body aches, etc. But all overdoses aren't created equal. Depending on the level you OD'ed, sometimes you'll just pass out and then come out of it yourself, or you'll need to be medically brought out of it by the paramedics. Either way, it doesn't feel good when you wake up, especially if you were pumped full of Narcan. Now that's pain. Overdose itself doesn't hurt. You will feel weird sometimes, higher than usual, maybe a tinging in your face and hands, blurry vision, and then it's just lights out. But no pain. Though I've never overdosed on anything other than heroin. Maybe OD'ing on coke or meth is different as far as the onset of pain.