Snot is a normal part of life, and when you get sick, it doesn't take a scientist to tell you that you're probably going to produce a whole lot more of it.
But what you might not realise is that the contents of your snot-filled tissue - including the colour and texture - can actually tell you a whole lot about your health. Including when it's time to take it easy, and when it's time to reach for the decongestants.
As this episode of American Chemical Society's Reactions series explains, snot contains a whole lot of cells and bacteria-fighting components that can affect the way it looks, and provide clues as to what your immune system is doing.
Let's start with the 'good' end of the snot spectrum. Runny, clear snot is a healthy part of your body's functioning, so if that's what's coming out - even if there's a lot of it - your immune system is likely doing fine.
But if your snot becomes white or yellow, and starts to thicken up, it's a sign that it contains a higher than usual amount of white blood cells, and your body is fighting the early stages of a virus.
Sort of like the amber light in traffic lights, yellow or white, thick snot is often a sign to slow down, stay hydrated, and rest up for a few days, so your immune system has a chance to get things under control.
Green snot, on the other hand, appears when things have escalated, the American Chemical Society team explains.
If your immune system (and snot) are being flooded with these cells, then, sorry to tell you, but your body is most likely already in over-drive fighting off the effect of a cold or flu, and you really need to take it easy.
So what do you do if you're dealing with yellow or green snot, but really need to power on and get back to work?
We'll let the team from Reactions run you though that one, but it turns out there are particular drugs that deal better with certain types of snot, so don't automatically reach for a decongestant.
And sometimes the best solution is just to let your nose run its course.
Check out the video above to get some insight into what your snot says about your health.
And remember, everyone's different, and this is very general advice - if you're feeling like crap, it might be time to log off the internet and go see a doctor.