Why Does Methamphetamine Always Make Me Nauseous After I Do

Why does methamphetamine always make me nauseous after I do a shot? I don't use often. I go to the methadone clinic and usually it takes a whole lot to get me sick especially to where I'm vomiting. Like real...in the book,.,sick!! But...everyone I shoot meth I vomit!!! I feel super high then I throw up. Why is this happening to me!? Is it my body's way of sayin its poisoned?