I started taking it after a series of really horrible hangovers. I would make sure to take it before i crashed for the night, and drink some water.
Interesting, after that, I never seemed to get hangovers anymore, except the one time i forgot to take it. I am not sure though if it was the milk thistle itself, or a combination of placebo and me being more tolerant to alcohol by the time i started this, that got rid of my hangovers. Thats the good thing about placebo though... it still works!