When I play live in the Summer, I sometimes take pills for my allergies. These pills are pseudoephidrine, a mild stimulant. I would never take the pills I take for allergies when I am about to sleep - diphenhydramine. Taking an allergy pill may not be considered "doping", but the situation is similar. To combat the symptoms of allergies, I take a pill that keeps me awake and alert rather than a pill that combats the symptoms but makes me sleepy.
If I were to take several of these pills while playing, when not suffering from allergies, that would be doping. I have seen many people, especially younger people who are obviously not "straight" when playing. A few years ago, at a WPT event, I saw one kid at my table who didn't look "right". His pupils were dilated, he seemed hyper focused, and he acted quickly and decisively on every decision. Pretty soon, his friend showed up to talk to him. I guess the friend had just busted. The friend looked exactly the same, talked in a frenzied manner and was almost ignored by the first guy who couldn't take his eyes off the table. Maybe one or both of them were legally prescribed Ritalin or something like that and decided to take a bunch of it that night.
There is definitely some doping going on during live play.
