and btw depending on the person, taking prescription medication (whether its Antabuse, xanax, gabapentin or whatever) and also drinking a lot causes the most absurdly strong, lengthy and horrible hangovers.
Also some medications have very lengthy half-lives (such as Valium which is 30h+, xanax is 6-12h) so even if you take one and wait a few hours, you'll still get absurdly strong hangovers and blackout etc.
I'm going to guess that he doesn't keep track of when he takes medication or how much he takes at all so its no coincidence he has so many issues.
and just a pro tip: if you take prescription medication and also drink, always make sure you keep a log of the last time you took medication and don't fuck around with it. You can die from that shit.