Sniff. Sniff. Is your nose running? Better go catch it!
OK, so that's an old joke and probably not a very good one either. But runny noses are something all of us have to deal with from time to time.
Mucus is probably not something you want to give a lot of thought to. After all, it is sort of icky. But it does do important things for your body. Mucus keeps bad germs, bacteria, pollen and other harmful things in the air out of your lungs by trapping them in your nose.
As mucus stops these things and builds up inside your nose, it often dries out and you need to blow your nose to get the harmful things out before they start to irritate your nose. If your nose does start to get irritated, you might have to sneeze to expel the harmful invaders.
At other times, though, mucus might run out of your nose for several different reasons. When this happens, we say you have a runny nose, and it's time to reach for the tissue box. Of course, scientists and doctors have a fancy name for a runny nose. They call it rhinorrhea.
For example, when you get sick with a cold or the flu, your body senses that it's under attack. In response, it begins to make even more mucus to fight off the invading germs, so you don't get even sicker. When this happens, the mucus has to have some place to go, so it comes out of your nose, drains down your throat and sometimes even clogs your sinuses, making your head feel stuffy.
A similar thing occurs in people who have allergies. If you're allergic to something, whether it's pollen in the air or hair from an animal, your body sees those things as invaders, like germs, when you come into contact with them. When that happens, your body starts making more mucus, just like when you have a cold or the flu.
A runny nose can also happen when you cry. This is because your tears drain through tear ducts that empty into your nose. Inside your nose, they mix with mucus and your nose starts running.
You might also notice that your nose runs when it's really cold outside. This happens because your nose tries to warm up the cold air before sending it down to your lungs. Blood vessels inside your nose open up to allow more warm blood to come to your nose to help warm the air. This also causes more mucus to be produced, which makes your nose run.
A runny nose can be a pain, but most doctors usually don't worry about it too much, since it's not considered a serious problem. However, if you have allergies at certain times of the year, a doctor may prescribe an antihistamine for you that will help reduce runny noses and help you feel better.