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At some point, we’ve all had a booger dangling from our nose or quickly grabbed for a tissue after a messy cough or sneeze.

But what exactly are these hard or moist, greenish chunks that every human has in their nose?

Let’s dive into the nitty-gritty of boogers:

  • What are they made of (and NOT made of, despite what your schoolyard friends used to tell you)?
  • How are they different from snot?
  • What processes in your body are responsible for everyone’s least favorite nose accessory?

The first and foremost ingredient in a typical booger is nasal mucus, which is often called snot.

Your nose and throat produce up to 2 quarts of snot each day for a few key reasons:

  • It’s a lubricant to keep your nose and sinuses wet, which protects them from irritation and from other objects (like your fingers or foreign matter that can scrape against your nasal tissues).
  • It’s a shield to protect the incredibly thin and delicate tissue and blood vessels in your nostrils and sinuses.
  • It’s a trap to help catch and drain out intruders like dust, pollen, and bacteria and viruses that can cause infections, allergies, and other types of nasal swelling.

But your body can’t hold in all that snot forever. Much of it gets tossed out of your sinuses and into your nose for drainage.

When snot brings along the substances it captured when it was moist and then dries out, it can turn lots of interesting colors. You might see browns and yellows caused by dirt and pollen or greens caused by dead inflammatory cells that change color when exposed to air.

Simply put, boogers are your body’s way of getting rid of extra snot.

But in case you heard some tall tales about them as a kid, here’s what boogers are NOT:

  • dead brain cells draining out of your skull
  • cerebrospinal fluid (CSF) leaking out of your spinal cord

The main difference between snot and boogers?

Snot is liquid mucus that drips out of your nose and sometimes down the back of your throat. More snot may drain from your nose when you’re sick or have a sinus infection because your body’s trying to push the infected bacteria or viral material out through your nose.

Boogers are made up of mucus that has collected particles of dust, pollen, bacteria, and other substances and drained into your nose, where exposure to the air has dried it.

They may also get bloody if they scrape against your delicate nasal tissue and break blood vessels that leak onto the dried mucus material.

Boogers are basically just dried mucus that’s collected in your nostrils.

Cells in your nose called airway epithelial cells (or goblet cells) are constantly making wet, sticky mucus to help protect your respiratory tract from anything in the air that can get into your lungs and threaten your health, such as:

  • bacteria
  • viruses
  • dirt
  • dust
  • pollen

Once mucus has captured these microscopic particles and microbes, tiny hairs in your nasal passages, called cilia, push mucus out into your nostril. If you don’t remove this mucus quickly, it’ll dry out and become boogers.

Your body makes snot that turns into boogers all day, every day.

But the snot that boogers are made of is both a defense mechanism against substances that get into your body and a way for your body to get rid of all that material in response to irritants, allergens, and infectious bacteria and viruses.

Producing snot is a key method your body uses to fight allergies and colds.

How boogers fight colds

When you get a cold, your body reacts to the presence of a cold virus by making extra histamine, an inflammatory chemical that makes the membranes in your nose swell up and produce extra mucus.

The extra mucus creates a thicker layer of mucus lining in your nose and sinuses. This keeps infectious material from reaching your nasal tissues and allows the mucus to push it out. Blowing your nose regularly helps clear the excess mucus and boogers out too.

Boogers and allergies

A similar process happens when you have allergies or when irritants like cigarette smoke get into your nose. Triggers like dust, mold, pollen, and other allergens make the membranes in your nose swell and amp up the mucus production.

This form of nasal swelling is called allergic rhinitis, which is just a fancy word for an inflamed nose caused by allergies to specific triggers. Swelling caused by triggers you’re not allergic to is called non-allergic rhinitis, and it usually goes away once the irritant is removed.

Both can cause itchiness, sneezing, coughing, and other symptoms associated with your body trying to get rid of irritants or allergens in your respiratory tract.

Boogers can seem gross, but they’re actually a byproduct of your body’s natural air filtration process. They’re a good thing — a sign that everything’s working just right in your mucus production system.

When you breathe in and foreign matter gets into your nasal passages, your mucus rises to the challenge and catches most, if not all, of that matter before it can get into your windpipe and lungs.