As a young teenager, I used to eat pizzas full of jalapeños and Tabasco on them, and very much enjoyed the spicy taste. In my mid-to-late 20s, I started feeling really sick when I ate these, even though at that point, it was far more infrequent. Now, in my post-35 age, I tried making a pizza at home with jalapeños (no Tabasco) on it for the first time in a long time, and the eating experience was indescribably good. As in, it turned the entire pizza into a completely different dish; from something rather bland into an explosion of taste in my mouth! This is what pizza is supposed to be like! Wow! I immediately told myself that I'm going to buy those little glass jars with jalapeño slices in them every time I make pizza from now on... Of course, X hours later, the next day, I "paid" for this lovely eating experience in the bathroom. What a nightmare. The less details I give about this, the better. You can probably imagine the kind of pain. I became completely sick and felt horrible for the longest time, shaking and freezing, lasting days. Clearly, my body is no longer able to handle/process the jalapeños, which couldn't make me more sad. I don't remember ever having any such problems whatsoever as a kid, or even until my (roughly) mid-20s. Possibly it's related to stress-induced internal stomach wounds or something. Is there something -- anything -- that can be done in order to allow me to eat these wonderful jalapeño pizzas yet not suffer that kind of torture afterwards? As fantastic as the taste was, I simply cannot justify putting myself through it again, knowing what it results in afterwards. 
Well... First of all, no. As alluded to in a comment, as one gets older, one's digestive system tends to be less accepting of what one puts in it. Nevertheless, "the dose makes the poison". You probably can't eat an inch-deep layer of jalapeños on your pizza anymore, but that doesn't mean you can't have an "explosion of taste". For one thing: Pickled jalapeños aren't just spicy. They're also vinegary and salty. And if I had to pick out what about a jalapeño pizza makes for an "explosion of taste", I'd actually rank the vinegar above the spiciness. Now, brands of pickled jalapeños also vary quite widely in spiciness, and in vinegariness. So if you could find a brand that was quite vinegary, and not as spicy (relative to the vinegar), you'd likely regret things less the next day. The other thing to consider is that when you eat the pizza you mostly taste the outside of the jalapeño; but your intestine is tasting the whole thing. Thick pieces of jalapeño, with a low surface-to-volume ratio, won't be much more taste-explodey than thin ones, but they will be more other-things-explodey. As an extreme example, if you swallowed a whole jalapeño without even chewing, it wouldn't taste that spicy... but you'd still pay as though it was. So consider mincing the jalapeños up. For that matter, consider sprinkling some of the jalapeño brine on the pizza after cooking. 