Why does spicy food make your nose run?

Because it is not that strong to make me run.

No.

Our nose consists of tiny hair and a sticky substance called mucus.

Can I use this mucus to stick my broken vase?

Gross.

Please don't do that and listen.

During breathing, the hair and mucus trap harmful substances.

Thus prohibiting them from entering deep inside the body.

Now, spicy food items like chili, mustard, horseradish and wasabi contain chemicals called capsaicin and allyl isothiocyanate.

When we eat such food items, the capsaicin and allyl isothiocyanate travel through the pharynx and reach our nose.

Here, the chemicals activate the heat sensing receptors.

Thus causing inflammation in our nose and irritation of the mucus.

Hence, as a defense mechanism more mucus is produced in our nose to get rid of these chemicals.

Thus making our nose run.