@why_at your comment and @throwup238's (thread name checks out) are IIRC the source of the debate. There is a porous surface area and tests/arguments of the type/size of the particle that can attach - perhaps they are inconclusive because there are lots of other things at play in the stomach and gut like biomes and various substances and surfaces and reactions. In my experience it worked and, based on my recollection I'm pretty sure in both scenarios above I would have been f*cked if not for the treatment.

I'm definitely open to the possibility that it might work differently on different people - we're not all clones.

Activated charcoal is just a high adsorption material with a lot more surface area (100-1000x or so) than stomach lining so anything floating around is more likely to be trapped by the charcoal than get absorbed by your digestive system.

It works with pretty much anything, good or bad, since it exploits a basic physical process of molecules sticking together.