Causes and Risk Factors of Increased Mucus Production

Mucus can tell quite the health story.

Too much mucus is a sign of a chronic respiratory condition, acute illness, and some types of chronic obstructive pulmonary disease (COPD). While mucus can be beneficial to the body, producing too much mucus can cause breathing difficulties and infection.

This article explains the causes of excess mucus and how genetics and lifestyle choices can add to the problem.

ways to reduce excess mucus in COPD

Verywell / Emily Roberts

Common Causes

Mucus is often mistaken for saliva, but the two substances are not the same.

Saliva is fluid produced in the mouth that helps you break down and swallow your food. Mucus lines the tissues while its slippery makeup traps potential irritants. Mucus contains dead cells and debris from the upper and lower respiratory tract, trapping them as well as bacteria so that everything can be coughed up and cleared from the lungs.

Mucus (also called sputum) is produced by goblet cells and submucosal glands. Overproduction or hypersecretion can occur due to dysfunction of these cells, an infection, inflammation, irritation, or debris in the respiratory tract.

People with chronic respiratory illnesses learn to live with increased mucus pretty much all the time. It's a fact of life. They can also experience acute flare-ups and cough up even more mucus.

Certain conditions are most responsible for triggering mucus production:

Respiratory Infection

Anyone can have a brief bout of a respiratory illness, which can cause increased mucus in the lungs. In fact, acute respiratory tract infections are one of the most common reasons people seek medical care in the United States.

The common cold is a common trigger of viral and bacterial respiratory tract infections. In some of the worst cases, the infections can lead to bacterial pneumonia.

Older man coughing into napkin
Daniel Allan / Getty Images

The lungs react to infectious organisms by mounting an immune response to get rid of the infection. Mucus production increases to help destroy invading microorganisms when you have an infection.

In general, the mucus should decrease to normal levels within a few days after your recovery.


Asthma is characterized by episodes of respiratory distress that are precipitated by weather changes or by substances such as airborne particles, pollen, and pet dander.

During an asthma attack, you may experience a "hypersecretion" of mucus. Even experts are hard-pressed to define what "hyper" mucus or even "too much mucus" is since it's assumed that the body produces about 1 liter of mucus per day.

Chronic Bronchitis

Chronic bronchitis, a type of COPD, is associated with excess mucus production in the lungs. The main cause is cigarette smoking.

A diagnosis of chronic bronchitis depends on having a cough with active mucus production most days of the week for at least three months (and for two years). Other lung diseases, such as tuberculosis, must be ruled out.

Mucus can increase even more than usual when bronchitis flares up.

Mucus and Phlegm

Many people use the words “mucus” and “phlegm” as if they were the same. But several differences separate them:

  • Mucus is a clear fluid that lines the nose, mouth, and throat. 
  • Phlegm is a type of mucus that is produced by the lungs and lower respiratory tract. The presence of phlegm means that the lungs and airways are irritated.
  • Mucus is usually expelled from the nose; phlegm is usually expelled from the lungs (through coughing). 

Emphysema and Bronchiectasis

As another type of COPD, emphysema is characterized by increased mucus production, coughing, and a predisposition to lung infections.

Bronchiectasis is a disease in which recurrent infections lead to a permanent widening of the airways. It often produces thick, foul-smelling mucus.

Pulmonary Edema

With pulmonary edema, a harmful increase in lung fluid can develop. It can lead to shortness of breath. In fact, difficulty breathing can cause people with pulmonary edema to awake soon after falling asleep, struggling for breath.

Compounded by more mucus than usual, breathing can become even more difficult. The mucus is often frothy in appearance and may have a pink color due to the presence of blood.


There are several hereditary conditions associated with increased mucus. Some conditions directly affect the lungs while others impair the muscles involved in breathing, which leads to increased respiratory mucus:

  • Cystic fibrosis is a genetic disease that affects multiple systems of the body, including the respiratory and digestive systems. Increased mucus is a primary characteristic of this condition.
  • Primary ciliary dyskinesia is a genetic disorder characterized by defective cilia (tiny, hair-like structures). It leads to increased mucus in the lungs and a predisposition to breathing difficulties and infections.
  • Neuromuscular conditions such as muscular dystrophy and spinal muscular atrophy can also lead to excess mucus because they impair muscle function. This, in turn, decreases lung movement when you inhale and exhale and reduces your strength and ability to cough. Then mucus pools in the lower lungs.

Lifestyle Risk Factors

Environmental irritants such as cigarette smoke and pollutants can cause the goblet cells to produce and secrete mucus while damaging the cilia and structures of the airways.

Exposure to these irritants, especially if you already have a lung disease, can substantially increase your risk of excess mucus in the lungs.

Common irritants include:

  • Indoor air particles (dust or pet hair)
  • Indoor or outdoor fumes or workplace emissions
  • Outdoor air pollution
  • Tobacco smoke


Sometimes, a combination of factors may be at play when it comes to excess mucus. For example, you may have stable emphysema, but you could produce extra mucus when you're exposed to cigarette smoke. Or you might have chronic bronchitis with increased mucus when you're sick with the flu.


Anyone who has ever dealt with a respiratory infection like bronchitis knows that excess mucus comes with the territory. Bronchitis is one of several medical conditions that can trigger this state. So can asthma, pneumonia, and emphysema as well as genetic and environmental factors. If a sharp healthcare provider can identify and treat the underlying cause, mucus production should return to normal.

A Word From Verywell

A cough may seem like "a little thing," but a persistent cough could be a sign that you have a condition that needs medical attention. So don't brush it off. It's smart to consult a trusted healthcare provider when your health may be on the line.

Frequently Asked Questions

  • Can allergies cause mucus?

    Yes. Allergies involve the release of histamine and other chemicals that irritate the mucus membrane inside the nose. The irritation causes excess mucus to be produced.

  • What can I do to stop mucus from reflux?

    Dietary changes are the first recommendation to ease laryngopharyngeal reflux or gastroesophageal reflux disease (GERD), both of which can increase mucus. Avoid foods that cause irritation, which may include alcohol, caffeine, carbonated drinks, spicy and fried foods, chocolate, peppermint, tomatoes, or citrus fruits. Eating small meals can also help.

  • How can I manage excessive morning mucus from COPD?

    Even with good practices like following your treatment plan and not smoking, morning mucus is very common with COPD. Use deep coughing to clear phlegm, talk to your doctor about possibly adjusting your medication, and meet with a sleep specialist, if you can. A better night's sleep could help ease some morning symptoms.

14 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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Additional Reading

By Deborah Leader, RN
 Deborah Leader RN, PHN, is a registered nurse and medical writer who focuses on COPD.