Olivia: Lots of people love the painful deliciousness of spicy food. At least... when it’s in your mouth. But why do foods that burn going in also burn going out?

Well, turns out, it's for the same biological reasons. Because in some ways, your butt is a lot like your mouth. Lots of spicy foods get their pungency from a chemical called capsaicin.

It’s produced by plants in the genus Capsicum, which includes chili peppers and their relatives. Capsaicin binds to a receptor expressed all over your nervous system called TRPV1. It has a handful of jobs, but it’s best known for its role in pain.

When there are risky levels of heat, this receptor tells your danger-sensing cells and other chemical messengers to send signals to your brain, which can make you feel pain. And because TRPV1 also interacts with capsaicin molecules, you feel the burn of habaneros in your mouth. According to your nervous system, hot peppers actually feel hot. Temperature-wise.

But TRPV1 receptors are in lots of places, and that includes your anus. See, the capsaicin you eat doesn’t get completely digested. Some of it does get absorbed by your body and sent to your liver to be broken down, but some of it sticks around and gets pooped out. Which means the TRPV1 receptors in your anus can interact with capsaicin just like the ones in your mouth. Ouch.

There are actually TRPV1 receptors all along your digestive tract, which is why some people get cramps or discomfort from spicy foods. And when your body’s being told things are way too hot, it usually tries to cool down. You sweat, your nose runs, and your mouth waters in an attempt to cool off and flush the offending substance.

Your intestines might get in on the action and throw in some water too. And that’s why your spicy food poop is sometimes... looser than normal. Now, consuming capsaicin regularly can actually make your body desensitized, possibly by decreasing the amount of certain chemical messengers, so your brain reports less pain.

Like, “oh ok, this happens all the time, there’s no fire or real danger, everything’s fine.” In fact, using low doses of capsaicin for pain relief is an active area of research. So go ahead and order those jalapenos on your pizza, because maybe eating spicy foods more regularly will help with those burning bowel movements. Even though it might not be super pleasant in the meantime.

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