In the movie 'Warrior', we see Tommy taking pills and he is later forced to give them up by his father after requesting his help in the training for the tournament 'Sparta'. So, what are these pills he is taking and are they medicinal or recreational?
Since there is no hard-evidence in the movie that would suggest either, nothing can be said definitively. But, I would say that those pills would most likely be anti-psychotic (neuroleptic) or anti-depressant of some kind.
The reason I say this is because Tommy (Hardy) is shown to have a tough childhood (mother's chronic illness and death, father's drinking issues) and later on his buddy in the Marines dies in friendly-fire, that eventually leads in Tommy going AWOL from active duty. Now I reckon, such scenarios are enough for any sane person to develop psychological issues.
NOTE: A friend suggested that he might be taking steroids, but that seemed a little off to me since Tommy was in the Marines (where I suppose steroids that are not prescribed would not be allowed) and frankly I doubt Tom Hardy's physique (though mammoth) is a result of steroid popping!
From an interview with Gavin O'Connor, the writer and director of the film:
In the documentary (linked above), the fighter, Mark Kerr, is linked to prescription painkillers (opiates). While the reference does not tell us plainly that Tommy is using painkillers, it's a reasonably good pointer in that direction. All the familial issues that Tommy has had as well as his experience in the marines might explain why/how he became addicted to them. It's useful to note that opiates, besides dulling pain, also promote a sense of well-being and euphoria.
Prescription painkiller abuse is quite rampant nowadays in all strata of society.