The reason that Jalapeno Peppers or other spicy foods cause our noses to run is due to the chemical contained in the Jalapeno Peppers known as capsaicin or allyl isothiocyanate.
The capsaicin or allyl isothiocyanate causes the burning sensation in our mouth and then it leads to watery eyes and runny noses which is normal.
The capsaicin or allyl isothiocyanate comes into contact with our bodies tissues and then burns those tissues and then causes the runny nose and watery eyes.
That makes Jalapeno Peppers or other spicy foods a great solution to get rid of congestion when you have a stuffy nose because your nose will begin to run soon after eating the Jalapeno Peppers.
Whenever I eat any Jalapeno Peppers I always need some tissues on hand because I will have tears in my eyes as well as a runny nose.