(backwards music) - [Woman] Weather leads us feeling stuffed up or sniffling.

Mucus can make us miserable but despite being a little icky, plum gets a bad rap.

This germ fighting goo contains cells and compounds that help us power through a cold.

And what turns up in our tissues can actually be a useful clue about the inner workings of our immune systems.

That's right.

It's time for the colorful chemical secrets of snot.

When we get sick with a cold or sinus infection our bodies begin to produce more mucus than normal to double down on the viral or bacterial invaders.

At this point, the consistency and color of snot also changes, going from healthy and clear to, well, not so clear.

Think of your snot like a traffic light yellow or white mucus turns up when you're congested and a higher concentration of living in dead white blood cells has thickened the discharge.

These immune cells might be there to battle a cold so slow down and take it easy.

If your mucus looks green, that could be due to the presence of a greenish enzyme called Myeloperoxidase which helps reduce acids in powerful immune cells called neutrophils.

With neutrophils hard at work, your body's probably in full go mode trying to kick a viral infection.

Red mucus means stop picking or blowing but fear not.

Small amounts of blood and mucus are totally normal and no cause for concern.

No matter what the color though too much mucus can be annoying or painful which might bring you to the drugstore for relief.

But what you decide to buy should match your symptoms and their root cause.

For example, if you're dealing with a runny nose, one possible culprit is histamine.

Histamine plays a pivotal role in allergies and other immune responses by increasing blood flow to snot producing body tissues.

Fortunately antihistamine drugs block some of the histamine from reaching their target mucus producing cells.

They can also cut down the production of histamine altogether.

All of which helps you to quit reaching for that tissue box or perhaps you're dealing with an arguably more annoying snot problem.

Congestion.

If your head is pounding with pressure decongestions work to reduce blood flow to nasal and sinus tissues that produce mucus.

This time by constricting the blood vessels themselves cutting down on the volume of snot and reducing inflammation should help ease pressure on your nose and sinuses.

That could clear things out a little bit easier but over reliance on both antihistamines and decongestants can decrease their effectiveness over time.

So sometimes it's just best to let your immune system do its thing.

But did you know that under the right conditions some runny noses have nothing to do with being sick or having allergies?

If you suddenly feel sniffly standing out at the bus stop, don't blame it on snot.

That's actually condensation from water in the cold air, hitting your warm nostrils.

So you don't have to feel quite so gross about wiping on your sleeve.

Yeah, we see you there, Kyle.