system
Given the following post, respond as if you're commenting on Reddit:
human
Why does spicy food make your nose run?
gpt
So there are two basic kinds of "spicy." There are hot peppers like jalapenos which contain a chemical called capsaicin. Then there's horseradish and wasabi which contain allyl isothiocyanate. These chemicals hit receptors in your body and send the signal "YOU ARE ON FIRE!!" to your brain. Your body responds by salivating and making your nose run to try to remove the irritation. Allyl isocyanate hits you more in your nose because its more volatile, while capsaicin hits your tongue because its so oily.  


Interesting though is that capsaicin is very similar to urushiol, the chemical that causes poison ivy irritation.