Why Does Your Nose Run When You Cry? Uncovering the Secret Passage Behind 'Tears and Snot'

When we cry buckets watching a sad movie or our eyes water profusely while chopping onions, an awkward phenomenon often accompanies it: our nose starts running uncontrollably. This comical chain reaction of 'tears and snot' isn't because your brain is confused, but because of a mysterious underground drainage system hidden in your face. Our brains constantly produce tears every day. These tears aren't typically for crying but serve to lubricate the eyeballs and wash away dust. Under normal circumstances, excess tears quietly flow through small openings on the inner side of the eyes into a duct called the nasolacrimal duct, draining directly into the nasal cavity. They then evaporate with breathing, so we don't notice anything. However, when we're overcome with emotion and cry heavily, the lacrimal glands secrete dozens of times more tears than usual in a short period. These overflowing tears, besides spilling from the eye sockets onto our laps, all rush like a flood into this drainage duct, the nasolacrimal duct, heading straight for the nasal cavity. Once a large volume of tears pours into the nasal cavity, they mix with the existing mucus there, diluting the normally thick snot until it's as watery as the tears. At this point, this liquid, mixed with tears, flows out of the nostrils due to gravity. So, the 'snot' that runs down when you cry is actually more than half your tears!