I keep alluding to the fact that not all mucus comes out of the body. Which means that some of it goes in the body. For saliva we knew this, but for nasal discharge (or snot) there are some rumors and half truths out there about how you should 'never swallow it!' But you can't always help it, it's the way the body is designed to work.
|See how easy it is for snot to travel to the stomach?!|
Whether you call it postnasal drip, phlegm, or spit - we end up with a lot of mucus in our digestive system, at least a few liters each day! So what happens to it? The trapped pathogens and foreign debris are destroyed by the acidic environment of the stomach and then broken down into their components for recycling or disposal just like the food we eat.
However, it's not recommended to hork back your snot if you're congested as it could get breathed into the lungs - instead, blow it into a tissue and dispose of it. This also helps keep whatever is infecting or irritating the sinuses and producing the mucus away from the interior of the body, preventing a sore throat from irritation. Just don't freak out when you feel the slimy mucus sliding down your throat - that's what it's normally supposed to do!