Causes and Risk Factors of Increased Mucus Production

Older man coughing into napkin
Daniel Allan / Getty Images
In This Article
Table of Contents

Many chronic respiratory conditions, acute illnesses, and environmental irritants are characterized by excess mucus, which is also described as excess sputum. For example, increased mucus production and decreased ability to rid the lungs of mucus is a hallmark of some types of chronic obstructive pulmonary disease (COPD).

Mucus is often mistaken for saliva, but the two substances are not the same. Saliva is fluid produced in the mouth to help you break down and swallow your food. Mucus contains dead cells and debris from the upper and lower respiratory tract, trapping it (and any organisms, such as bacteria) so they can be coughed up and cleared from the lungs.

While this is beneficial to your body, excess mucus production—particularly if it is uncleared and chronic—can have consequences such as breathing difficulties and increased risk of infection.

ways to reduce excess mucus in COPD
Verywell/Emily Roberts

Common Causes

With many chronic respiratory illnesses, you can have increased sputum just about all the time. You can also experience acute flare-ups at times, with even more sputum than usual. Even when you have healthy lungs, you can temporarily have excess sputum during a respiratory illness.

Mucus 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.

Damage to the cilia—tiny hair-like structures that help move mucus out of the lungs—may occur with smoking or due to some medical illnesses. And your ability to cough can be diminished due to atrophy (shrinking) of the muscles associated with coughing.

Conditions commonly characterized by excess respiratory mucus include the following.

Respiratory Infection

Anyone can have a brief bout of respiratory illness, which can cause increased mucus in the lungs. This can occur with a mild viral or bacterial respiratory tract infection, as well as with severe bacterial pneumonia.

The lungs react to infectious organisms by mounting an immune response to get rid of the infection. Sputum 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

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 have hypersecretion of mucus.

Chronic Bronchitis

Chronic bronchitis, a type of COPD, is associated with excess mucus production in the lungs. In fact, cough with sputum production every day for at least three months is part of the diagnostic criteria.

The mucus can increase even more than usual when the condition flares up.

Emphysema

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

Bronchiectasis

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

Pulmonary Edema

With pulmonary edema, a harmful increase in lung fluid can develop. Sputum is often frothy in appearance and may have a pink color due to the presence of blood.

Genetics

There are several hereditary conditions associated with increased mucus. Some conditions directly affect the lungs, while others impair the muscles involved in breathing, which secondarily 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 among the hallmark characteristics of this condition.

Primary ciliary dyskinesia is a genetic disorder characterized by defective cilia, which 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, which decreases lung movement when you inhale and exhale and reduces your strength and ability to cough. This leads to the pooling of mucus in the lower lungs.

Lifestyle Risk Factors

Environmental irritants such as cigarette smoke and pollutants also 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:

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

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

A Word From Verywell

An increase in the amount of mucus produced in the lung may lead to discomfort, difficulty breathing, and an increased risk of infections. Other characteristics, such as a variation in the color of the sputum or the degree of thickness or stickiness, can be a sign of changes in your condition.

If you notice increased mucus or a change in the mucus that you cough up, be sure to get medical attention.

Was this page helpful?
Article 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.
  1. Poole P, Chong J, Cates CJ. Mucolytic agents versus placebo for chronic bronchitis or chronic obstructive pulmonary disease. Cochrane Database Syst Rev. 2015;(7):CD001287. doi:10.1002/14651858.CD001287.pub5

  2. Rubin BK. Secretion properties, clearance, and therapy in airway disease. Transl Respir Med. 2014;2:6. doi:10.1186/2213-0802-2-6

  3. Ma J, Rubin BK, Voynow JA. Mucins, mucus, and goblet cells. Chest. 2018;154(1):169-176. doi.10.1016/j.chest.2017.11.008

  4. Asti L, Bartsch SM, Umscheid CA, Hamilton K, Nachamkin I, Lee BY. The potential economic value of sputum culture use in patients with community-acquired pneumonia and healthcare-associated pneumonia. Clin Microbiol Infect. 2019;25(8):1038.e1-1038.e9. doi.10.1016/j.cmi.2018.11.031

  5. Dunican EM, Elicker BM, Gierada DS, et al. Mucus plugs in patients with asthma linked to eosinophilia and airflow obstruction. J Clin Invest. 2018;128(3):997-1009. doi.10.1172/JCI95693

  6. Hill DB, Long RF, Kissner WJ, et al. Pathological mucus and impaired mucus clearance in cystic fibrosis patients result from increased concentration, not altered pH. Eur Respir J. 2018;52(6). doi.10.1183/13993003.01297-2018

  7. Morrow B, Zampoli M, Van aswegen H, Argent A. Mechanical insufflation-exsufflation for people with neuromuscular disorders. Cochrane Database Syst Rev. 2013;(12):CD010044. doi.10.1002/14651858.CD010044.pub2

  8. Yu Q, Yang D, Chen X, Chen Q. CD147 increases mucus secretion induced by cigarette smoke in COPD. BMC Pulm Med. 2019;19(1):29. doi.10.1186/s12890-019-0791-0

Additional Reading