Spicy food causes your nose to run because it contains a chemical compound called capsaicin, which is an irritant to humans. Just because you get a runny nose after eating spicy food doesn't mean you're not cut out to eat these kinds of foods. Capsaicin causes mucous membranes (meaning the linings of your nose and mouth) to become inflamed, and that inflammation causes your mucous membranes to produce extra mucous. Your runny nose is your body's way of trying to get rid of the offending agent by flushing it from your system. The amount of capsaicin in typical spicy foods is not enough to do damage to your nose or mouth, and as long as you enjoy eating spicy foods it's fine for you to do so. If you have eaten too much spicy food and feel uncomfortable you can drink milk to relieve the heat. You may find that over time you are able to tolerate spicier and spicier food as your body becomes accustomed to higher levels of capsaicin. It is a common misperception that spicy foods can cause ulcers in your stomach or small intestine. In reality spicy foods do not cause ulcers, but they can irritate existing ulcers.
If you have any concerns that your reaction to capsaicin may represent a more serious medical condition you should make an appointment with your doctor
to discuss this issue. However, you should be relieved to know that a runny nose after spicy food is completely normal.