What diseases are caused by mucus?

The Slime That Keeps You Healthy

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Mucus has several names. Snot, the sticky goo that pours from your nose during a cold. Or phlegm, the gunk that can clog your lungs and make you cough. You probably aren’t a fan of the stuff. But mucus is so much more than a runny nose. Your body is making mucus all the time. And it plays an important role in keeping you healthy.

“Mucus and phlegm get sort of a bad reputation,” says Dr. Richard Boucher, a lung expert at the University of North Carolina. “People think about it as something you’re supposed to cough up and get out. That it’s a bad thing. But in truth, mucus really is the interface between you and the outside world.”

Mucus lines the moist surfaces of your body like the lungs, sinusesThe hollow spaces in your skull around your nose, eyes, and forehead., mouth, stomach, and intestines. Even your eyes are coated with a thin layer of mucus. It serves as a lubricant to keep tissues from drying out. It’s also a line of defense.

“Mucus is very important for filtering out materials that you breathe in through your nose, such as dust and allergens and microorganisms,” says Dr. Andrew Lane, an ear, nose, and throat expert at Johns Hopkins University. “Anything that you breathe in gets stuck in the mucus, like flypaper.”

Mucus at Work

In the next hour, you’re going to inhale thousands of bacteria. But you’ll never know it. Bacteria land on the mucus-lined surface of the lungs and get trapped. Then little hairs called cilia go to work. They push the mucus up and out of the lungs with all the trapped bacteria, viruses, and dust.

“It comes up at sort of a nice slow rate to the back of the throat,” Boucher says. “And if you’re normal and healthy, you never feel it and you just swallow it.”

The mucus, together with the bacteria and other trapped substances, then goes to the stomach and eventually pass out of the body.

Your body makes a lot of mucus, although no one’s quite sure how much. Mucus is mostly water. But it also contains special proteins, sugars, and molecules that help the body control harmful germs.

Usually you’re not aware of all the mucus that slowly flows through your body. That is, until you get sick.

Too Much Mucus

You usually only notice mucus when you’re making too much of it. Or if it changes consistency.

An infection can make mucus thicker and stickier. Infections also lead to inflammationHeat, swelling, and redness caused by the body’s protective response to injury or infection. in the mucous membranes that line the nose and the rest of your airway. This can cause certain airway glandsOrgans that produce and release substances into the body. to make more mucus. That mucus can get thick with bacteria and cells that arrive to fight the infection. That can stimulate even more mucus production.

“When mucus is particularly excessive, it can be bothersome in terms of runny nose, clogged nose, and post-nasal drip,” says Dr. Bruce Bochner, an allergy expert at Northwestern University. Post-nasal drip is when excess mucus from the back of the nose gathers and drips down the back of the throat. It’s a common cause of a cough.

Allergies can also cause your body to make extra mucus. When you have an allergy, your immune systemThe system that protects your body from invading viruses, bacteria, and other microscopic threats. overreacts to a harmless substance, like pollen, dust, or animal dander. Cells in your airway then release substances, like histamine.

Histamine can make you sneeze. It also causes the mucous membranes in the nose to swell and the glands to make more mucus. Bochner’s team studies how certain proteins on immune cells control allergies and inflammation. They’re also looking at how certain components of mucus might help fight inflammation.

“There are two general types of secretions that that are made in the nose,” Bochner explains. Things like allergies, eating spicy food, and being outside in the cold can result in a more watery nasal leakage.

Your body usually makes thicker mucus when you have a cold (caused by viruses) or sinus infection (caused by bacteria).

Most mucus problems are temporary. But producing too much mucus contributes to some serious conditions. This includes cystic fibrosis, a genetic disorder that causes mucus in the lungs to become thick and glue-like. Boucher and his colleagues are working to find new treatments for cystic fibrosis and related lung diseases.

Colors of Mucus

Mucus can come in a range of colors. This won’t surprise you if you’ve ever looked closely at your tissues after blowing your nose.

Mucus is normally clear. During a cold, you may find that your snot is cloudy or yellowish. Proteins released by the cells that cause inflammation can get stuck in the mucus and give it this color, Lane explains. He’s currently studying how cells in the nose and sinus are involved in long-term inflammation, called chronic sinusitis.

Brown or black mucus is more common in heavy smokers and some types of lung disease. Greenish, brownish, or bloody colors may signal a bacterial infection.

But that’s not always the case. It can be difficult to figure out what’s wrong simply by your mucus color. Since many things can cause your body to make too much mucus, doctors rely on other clues to diagnose and treat the problem.

Wonders of Mucus

While excess snot and phlegm aren’t pleasant, you wouldn’t want to go without mucus.

“Mucus creates a layer of protection between the outside world and you. So it’s very, very important,” Lane says.

It’s not just important for people. It’s also the slime that allows a snail to move across the ground. It’s the slippery coating that protects fish against bacteria in the water. “It’s a really wonderful material,” Boucher says.

But maybe your mucus isn’t feeling so marvelous. If excess mucus is getting you down, see the Wise Choices box for tips on getting rid of it.

The damage to the lungs associated with bronchiectasis is permanent, but treatment can help prevent the condition getting worse.

In most cases, treatment involves a combination of medication, exercises you can learn and devices to help clear your airways. Surgery for bronchiectasis is rare.

There are a number of things you can do to help relieve the symptoms of bronchiectasis and stop the condition getting worse, including:

Exercises

There are a range of exercises, known as airway clearance techniques, which can help to remove mucus from your lungs. This can often help improve coughing and breathlessness in people with bronchiectasis.

You can be referred to a physiotherpist, who can teach you these techniques.

Active cycle of breathing techniques (ACBT)

The most widely used technique in the UK is called active cycle of breathing techniques (ACBT).

ACBT involves you repeating a cycle made up of a number of different steps. These include a period of normal breathing, followed by deep breaths to loosen the mucus and force it up; then you cough the mucus out. The cycle is then repeated for 20 to 30 minutes.

Don't attempt ACBT if you haven't first been taught the steps by a suitably trained physiotherapist, as performing the techniques incorrectly could damage your lungs.

If you're otherwise in good health, you'll probably only need to perform ACBT once or twice a day. If you develop a lung infection, you may need to perform ACBT on a more frequent basis.

Postural drainage

Changing your position can also make it easier to remove mucus from your lungs. This is known as postural drainage.

Each technique can involve several complex steps, but most techniques involve you leaning or lying down while the physiotherapist or a carer uses their hands to vibrate certain sections of your lungs as you go through a series of "huffing" and coughing.

Devices

There are also a number of handheld devices that can help to remove mucus from your lungs.

Although these devices look different, most work in a similar way. Generally, they use a combination of vibrations and air pressure to make it easier to cough out any mucus.

Examples of these devices include the flutter, the RC cornet and the Acapella.

However, these devices aren't always available on the NHS, so you may have to pay for one yourself. They usually cost £45 to £60.

Medication

In some cases, medications to make breathing or clearing your lungs easier may be prescribed. These are discussed below.

Nebulised medications

Occasionally, medication inhaled through a device called a nebuliser may be recommended to help make it easier for you to clear your lungs.

Nebulisers are devices consisting of a face mask or mouthpiece, a chamber to convert the medication into a fine mist, and a compressor to pump the medication into your lungs.

A number of different medications can be administered using a nebuliser, including salt water solutions. These medications help to reduce the thickness of your phlegm so it's easier to cough it out. Nebulisers can also be used to administer antibiotics, if necessary (see below).

However, while the medications used with a nebuliser can be provided on prescription, the nebuliser device itself isn't always available on the NHS. In some areas, a local respiratory service may provide the device without charge, but if this isn't an option, you may have to pay for a device.

Bronchodilators

If you have a particularly severe flare-up of symptoms, you may be prescribed bronchodilator medications on a short-term basis.

Bronchodilators are inhaled medications that help make breathing easier by relaxing the muscles in the lungs. Examples of this type of medication include beta2-adrenergic agonist, anticholinergics and theophylline.

Antibiotics

If you experience a worsening of symptoms because of a bacterial infection (known as an "infective exacerbation") then you'll need to be treated with antibiotics.

A sample of phlegm will be taken to determine what type of bacteria is causing the infection, although you'll be initially treated with an antibiotic known to be effective against a number of different bacteria (a broad spectrum antibiotic) because it can take a few days to get the test results.

Depending on the test results, you may be prescribed a different antibiotic, or in some cases, a combination of antibiotics known to be effective against the specific bacteria causing the infection.

If you're well enough to be treated at home, you'll probably be prescribed two to three antibiotic tablets a day for 10-14 days. It's important to finish the course even if you feel better, as stopping the course prematurely could cause the infection to recur quickly.

If your symptoms are more severe (see symptoms of bronchiectasis for a detailed description) you may need to be admitted to hospital and treated with antibiotic injections.

Preventative treatment

If you have three or more infective exacerbations in any one year, or your symptoms during an infective exacerbation were particularly severe, it may be recommended that you take antibiotics on a long-term basis. This can help to prevent further infections and give your lungs the chance to recover.

This could involve taking low-dose antibiotic tablets to minimise the risk of side effects, or using an antibiotic nebuliser (see above for more information about nebulisers).

Using antibiotics in this way does increase the risk that one or more types of bacteria will develop a resistance to the antibiotic. Therefore, you may be asked to give regular phlegm samples to check for any resistance. If bacteria do show signs of developing a resistance, then your antibiotic may need to be changed.

Surgery

Surgery is usually only recommended where bronchiectasis is only affecting a single section of your lung, your symptoms aren't responding to other treatment and you don't have an underlying condition that could cause bronchiectasis to recur.

The lungs are made up of sections known as lobes – the left lung has two lobes and the right lung has three lobes. Surgery for focal bronchiectasis would usually involve removing the lobe affected by the bronchiectasis in a type of operation known as a lobectomy.

Surgery won't be used if more than one lobe is affected, as it’s too dangerous to remove so much lung tissue.