You take a bite of something spicy. Within moments, your nose starts running, your eyes begin to water, and you may even begin to sweat. Then you wonder whether you should have ordered something milder. So what’s going on? Is the chilli really making your body hotter, or is your brain simply being tricked?
A runny nose may seem like an odd side effect of eating spicy food, but it’s actually your body’s clever way of protecting itself.
The main reason behind this reaction is capsaicin, the chemical that gives chilli peppers their spiciness and heat. This chemical doesn’t actually increase the temperature in your mouth. Instead, it binds to special nerve receptors called TRPV1 receptors, which normally respond to heat and pain. When these receptors are activated, they send signals to your brain similar to those produced by something hot. As a result, your brain interprets the chilli as heat, even though your mouth isn’t actually burning.
In other words, your brain is temporarily fooled into thinking your body is overheating or has encountered an irritating substance.
Your nervous system quickly responds. Blood vessels in the mouth and nose widen to help release heat, and mucus-producing glands become more active. The extra mucus helps trap and wash away what your body perceives to be an irritant. This is why your nose starts to run, your eyes may water, and you might even begin to sweat, all despite the fact that the chilli isn’t causing any real heat damage.
In reality, your body is reacting to a false alarm. Capsaicin has simply activated the same pathways that respond to heat and pain. Sometimes, a tiny molecule can convince your brain that your mouth is on fire, and your body responds exactly as if it were.
