What Is Mucus?

Mucus is a slippery fluid that is produced by your body naturally. It is produced by glands in organs, including the mouth, nose, throat, stomach, intestines, and vagina. Although mucus production is natural and healthy, excess mucus production can be a sign of illness, including the common cold. 

Knowing about the role mucus plays in your body when it’s healthy can help you spot when your mucus is abnormal, which could indicate that you’re sick. 

What Is Mucus?

Mucus is produced in order to protect the body and keep it functioning in a healthy way. The function of mucus depends on its location in your body: it can serve as a lubricant, a protective barrier, or a substance that helps trap foreign bodies or flush them out of your body.

So, while mucus might seem gross, it’s important. Mucus in your lungs can help remove bacteria that might otherwise cause infection. Mucus in your nose can help prevent viruses, bacteria, and allergens from entering the body. Vaginal mucus can help women get pregnant, or avoid pregnancy if they wish, while mucus in the gut helps our digestive system function.

Mucus is produced by mucus glands. The structure of mucus varies depending on its purpose and the area of your body in which it is found. All mucus is made from mucin, a substance that your body produces, but really it is mostly water. In fact, 90% of mucus is water. Most mucus is slick and clear. 

Why Do We Have Mucus?

Under normal circumstances, mucus helps keep you healthy. There are a few ways that this works, including:

  • In your lungs and gut, mucus makes it harder for bacteria to stick together. In turn, that can reduce your risk for infections.
  • In your nose, mucus drips down to clear out the nostrils, taking dirt, allergens, and other disease agents with it.
  • In your throat, mucus provides the lubrication that you need to swallow and speak without discomfort.
  • In your cervix, mucus accepts, filters, prepares, and releases sperm for successful transport to the egg and fertilization.

Most adults will produce between 1 and 1.5 quarts of mucus a day—most of it in the respiratory tract, which includes the mouth, nose, throat, and lungs. Most people don’t notice their mucus until something goes wrong. 

Mucus and Sickness

With some illnesses, your mucus becomes very noticeable. Think about the common symptoms of a cold—congestion, coughing, and sore throat are all linked to mucus.

When you’re fighting various viral or bacterial illnesses, your mucus becomes thicker. That makes it move less easily, and become more noticeable. Your body also produces more mucus when you’re sick with some illnesses, in an attempt to flush out germs that are making you ill.

There are a few things you can do to control mucus when you are sick. First, drink plenty of water. Remember that mucus is mostly made from water, so staying hydrated can make your mucus thinner and therefore easier to move around.

When you feel the need to cough, sneeze, or blow your nose, listen to your body. These actions are the body’s way of expelling mucus that has done its job and caught germs and other intruders.

How To Get Rid of Mucus

Controlling mucus while you’re sick won’t make your illness go away, but it can help you feel more comfortable. If you’re experiencing too much mucus in your nose or chest, try the following:

  • Breathe in steam: The water in the steam will help break up the mucus and make it easier to cough up or blow out into a tissue. 
  • Use a humidifier: Similarly, keeping the air moist can help move your mucus around. 
  • Use saline spray or nasal irrigation: This can push the mucus out of your nose and help clear your sinuses. 

Some over-the-counter medications can also help. Expectorants, like Mucinex (guaifenesin), break up chest congestion, while decongestants, like Sudafed, are more effective for nasal congestion.

Colored Mucus and Your Health

Your mucus can also give insight into your health. Here are details about the different colors of mucus:

  • Clear mucus is a good sign. In healthy individuals, mucus is clear and thin. 
  • Yellow mucus can indicate that you’re a bit dehydrated, especially if it’s also thicker than usual. It can also indicate a minor illness like a cold.
  • Green mucus that’s rich in color is cause for concern—it can indicate that you have a bacteria infection.
  • Red or brown mucus can indicate blood or dirt.

Mucus alone isn’t enough to determine whether you have an infection, so consider other symptoms as well. For example, if you have a fever, that’s a good indication that your body is fighting off an illness. Any time your symptoms are enough to make you concerned, reach out to a healthcare provider for advice. 

Mucus and Lung Disease

In rare cases, mucus can contribute to disease and illness. Cystic fibrosis (CF) is a genetic condition that causes mucus to be thick and sticky. This undermines the way that mucus normally protects the body. Instead of flushing out germs, mucus traps bacteria and other germs in people with CF, increasing their risk for lung infections. 

Although CF is commonly thought about as a lung disease, it has an impact on mucus throughout the body. Mucus build-up in the pancreas causes the body to not release enough digestive enzymes, causing nutrient deficiencies. Mucus in the liver can contribute to liver disease. Because of this, the treatment of CF includes medications that are meant to thin mucus.

Mucus Outside the Respiratory Tract

During cold season, the mucus in your respiratory tract might be the most common, since it can indicate you're fighting a virus. However, mucus plays a role throughout the body, during times of sickness and health.

Healthy people produce mucus in their large intestines. Part of the purpose of this fluid is to help your body process stool. Because of that, you might notice mucus in your stool when you poop. Normally, this isn't a cause for concern. However, if you suddenly notice a change in the amount of mucus in your stool, or notice that there's blood in your stool as well, you should speak to your healthcare provider. Those changes could indicate an underlying condition like irritable bowel syndrome or ulcerative colitis, a condition that affects the mucus membrane of the intestine.

Women also produce vaginal mucus. This is produced by the cervix. The amount and consistency of vaginal mucus changes throughout a woman's menstrual cycle. Monitoring the changes in vaginal mucus can help women identify when they are ovulating. Right around ovulation cervical mucus is plentiful and often has a slippery consistency like raw egg whites. This type of mucus is meant to help sperm to reach the egg. Having sex—or avoiding it—when this type of vaginal mucus is present can help increase or reduce the chances of pregnancy. As women's cycles become more irregular with age, their amount of vaginal mucus can change as well.

A Word From Verywell

Mucus might be icky, but it’s important. It helps keep you healthy and, when that fails, can help you overcome sicknesses. But it can also lead to a lot of discomfort when you have too much of it. Controlling mucus when you don’t feel well can help make a common cold a bit more manageable. 

Remember that while mucus helps keep you healthy, it can make others sick. If you cough or sneeze up any mucus, be sure to wash your hands and disinfect anything that you’ve touched. By doing that, you can help keep your mucus to yourself and minimize the risk of spreading illness to the people around you. 

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Scripps. 5 fun facts about boogers.

  3. UNC Health Talks. Mucus, our body’s silent defender

  4. Portnoy J. Throat mucus/tickle/lump sensation. ENT and Allergy Associates. 

  5. Centers for Disease Control and Prevention. Common cold.

  6. Cystic Fibrosis Foundation. About cystic fibrosis

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By Kelly Burch
Kelly Burch is has written about health topics for more than a decade. Her writing has appeared in The Washington Post, The Chicago Tribune, and more.