Why Does Your Nose Run When You Cry?

Press play on a sad movie and you might find your face turning into a sopping wet mess. It’s not just the tears (and any makeup said tears have displaced)—it’s also all the snot.

While the evolutionary reasoning behind human tears remains unclear, how those tears happen is less murky. Emotional arousal causes your brain to send messages to your tear ducts instructing them to produce tears. 

But those messages don’t go to your nose. So why has it seemingly kicked mucus production into high gear? Actually, it hasn’t.

When you cry, some tears exit your eyes simply by rolling down the length of your face. Others, however, drain through your tear ducts and into your nasal cavity. There, they combine with mucus, generating a surplus of fluid that spills from your nose.

“You’re not making more mucus, it’s just the tears draining and mixing with the mucus [that’s already there],” Dr. Erich Voigt, M.D., director of NYU Langone Medical Center’s department of general and sleep otolaryngology, told SELF.

The same isn’t true of certain other circumstances that cause a runny nose. When you eat something spicy, for example, your mucous membranes do make more mucus—it’s their way of trying to flush out the “spicy” chemicals before they can interfere with your respiratory system. Your mucous membranes ramp up output in the cold, too, in order to warm up and moisten that dry, chilly air before it reaches your lungs. 

One powerful blow into a tissue may seem like the best way to clear out all that excess mucus—but too much force can cause other issues. Here’s how (and how not) to blow your nose.

[h/t SELF]

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.