Yeah, same here. For me, it’s not the “ring of fire.” I haven’t had that in about 20 years (I’m not exactly sure how that works biologically. I did used to get it, but it stopped.) But if I really get crazy on the habaneros or similar, there’s about a one in three or four chance that I’ll need some Imodium the next day.
I’m thinking that is malic acid, an essential ingredient in Atomic Warheads.
Could also just simply be citric acid (or even ascorbic acid.) Pretty sure that’s what was dusted on the Super Sour Tear Jerkers when I was a kid.
I’ve seen combinations of malic, citric, and tartaric acid on sour candies. plus, the typical “acid blend” used in winemaking is composed of those three.
Mary Roach wrote an article in Smithsonian Magazine in which spice tolerance was explained as cumulatively destroyed pain receptors:
The Gut-Wrenching Science Behind the World’s Hottest Peppers
When you get to actual physical damage it is no longer considered “spicy” but is classified as “caustic.” Caustic agents are not usually edible.
Even then, I don’t think that the pain receptors are damaged, exactly. I think in time, they will recover and will once again react stronger to chile.
In my case, I grew up in New Mexico and regularly ate all kinds of very spicy food. Eventually, it didn’t seem “spicy” anymore. The chile became more like a seasoning, similar to salt. It brought out the flavors, but too much would overwhelm the food. After being away for years, I have a much lower tolerance for chile, and dishes I once easily ate are now very spicy.