Is That Sputum You’re Coughing Up? (2023)

Sputum, or phlegm, is a type of mucus secreted by cells in the lower airways (bronchi and bronchioles) of the respiratory tract. It differs from saliva, which is produced higher up in the mouth.

Sputum may contain dead cells, foreign debris inhaled into the lung, bacteria, and white blood cells that protect the airway from infection. The quantity, texture, and color of sputum can help to diagnose lung cancer and other medical conditions that affect sputum production.

This article explains what sputum is and looks like. It discusses sputum culture tests and procedures, such as sputum induction, that are used to assess sputum when identifying and treating respiratory illnesses.

Sputum Types

Sputum is secreted into the lower airways (bronchi and bronchioles) of the respiratory tract. It is produced by cells called goblet cells that line the airway, and it contains immune cells to fight off bacteria. It works with small structures in the airway called cilia to trap and remove foreign substances.

Sputum is not the same as saliva, a substance secreted in the mouth to help with digestion. The terms sputum and phlegm are used interchangeably.

Sputum or phlegm is coughed up from the bronchi, bronchioles, and trachea rather than glands in the mouth and throat. It may include foreign matter from air pollution or smoking cigarettes, as well as bacteria from an infection, or blood due to cancer, airway damage, and pulmonary edema.

The term mucus may sometimes be used instead of sputum, but sputum refers to that mucus specifically secreted in the respiratory tract, whereas mucus may also be produced in the gastrointestinal tract, urological tract, and genital tract.

What Is Mucus?

Tests to Evaluate Sputum

Sputum may be analyzed in the lab to determine its contents in order to evaluate infections or look for cancer. Tests may include:

  • Sputum culture: A sputum culture is done in a laboratory to identify the presence and type of cells in a sputum sample that may cause disease. If a specific bacteria is found, the lab can then do further tests to figure out which antibiotic is most effective against that bacteria (sensitivity testing).
  • Sputum for tuberculosis: A sputum sample may be obtained to look for tuberculosis, though several samples are often needed in order to find one that is diagnostic.
  • Sputum cytology: In sputum cytology, a sample of sputum is evaluated under the microscope. This can be done to look for signs of tuberculosis or signs of cancer cells. However, sputum cytology is not a reliable lung cancer screening tool. If cancer cells are found, however, it can be diagnostic of lung cancer and further tests determine the location of the cancer.

Sputum Induction

Some people may have difficulty coughing up sputum from deep in the lungs. A cytology technique called sputum induction, first developed to diagnose pneumonia in people living with human immunodeficiency virus (HIV), is now used to assess diseases such as asthma, chronic obstructive pulmonary disease (COPD), or idiopathic pulmonary fibrosis. It involves inhaling a mist of Albuterol (salbutamol) followed by saline to make sputum production easier.

Treatment Options for Idiopathic Pulmonary Fibrosis

What Sputum Colors Mean

Sputum qualities can include many colors and different consistencies, and these can help to diagnose certain conditions. For example:

  • Clear sputum: Clear sputum is usually normal, although it may be increased in some lung diseases.
  • White or gray sputum: White or grayish tinged sputum can also be normal, but may be present in increased amounts with some lung diseases or precede other color changes associated with other conditions.
  • Dark yellow/green sputum: A type of white blood cells known as neutrophilshave a green color to them. These types of white blood cells are attracted to the scene of bacterial infections, and therefore bacterial infections of the lower respiratory tract, such as pneumonia, may result in the production of green sputum. Yellow-green sputum is common with cystic fibrosis as well.
  • Brown sputum: Brown sputum due to the presence of tar is sometimes found in people who smoke. Air pollution or exposure to smoke from other causes like a house fire are other causes. Sputum may also appear brown or black due to the presence of old blood. Brown sputum is also common with "black lung disease." These diseases, called pneumoconioses, occur from inhaling substances like coal into the lungs.
  • Pink sputum: Pink, especially frothy pink sputum may come from pulmonary edema, a condition in which fluid and small amounts of blood leak from capillaries into the alveoli of the lungs. Pulmonary edema is often a complication of congestive heart failure. Pink or blood-tinged sputum is commonly caused by tuberculosis worldwide.
  • Bloody sputum: Bloody sputum, even just a trace of blood-tinged sputum, should always be evaluated. Coughing up blood (hemoptysis) can be serious, and is the first sign of lung cancer in 7% to 35% of cases.

Coughing up Blood in Sputum

Blood in sputum is always serious and requires immediate medical evaluation. It can be a sign of lung cancer or pulmonary embolism, a condition in which a blood clot breaks off and travels to the lungs. Even a teaspoon of coughed-up blood is considered a medical emergency. Coughing up a fourth of a cup of blood is considered massive hemoptysis and carries a poor prognosis.

Causes of Increased Sputum

Some conditions that result in increased production of sputum include:

  • Chronic bronchitis: Chronic bronchitis results in increased sputum. The criteria for a diagnosis of chronic bronchitis includes a daily cough productive of sputum
  • Bronchiectasis: A condition in which the tubes that carry air in and out of your lungs get damaged, causing them to widen and become loose and scarred.
  • Pulmonary edema
  • Overproduction of sputum can also be caused by smoking and exposure to air pollution.

Is That Sputum You’re Coughing Up? (1)

Decreasing Sputum

There are a number of ways in which to decrease sputum production, but the most important step is to diagnose and treat the underlying cause.

With air pollution and smoking, the underlying cause is the body's attempt to rid itself of foreign matter, and an overproduction of sputum is a normal response. Tobacco smoke causes paralysis in cilia. They can't move sputum up to the mouth due to the lower mobility, so it accumulates in the airways. Removing the source is the best approach.

Medications that may help decrease sputum include aerosol treatments and expectorants. Treatments such as postural drainage may be effective in some situations.


Sputum is a mix of cells, foreign matter, and white blood cells produced in the respiratory tract. An increased amount of sputum is often the body's attempt to protect and heal damage to the airways. Contact your healthcare provider if you have chronic or concerning symptoms. An accurate diagnosis may lead to earlier treatment and improved outcomes.

Frequently Asked Questions

  • What does green phlegm mean?

    Green phlegm is a possible sign of a bacterial infection.Coughing up discolored phlegm can be worrisome, but the color actually shows that your body is fighting the infection. If your symptoms worsen or don’t improve, you may need antibiotics to clear the infection.

    Learn More:An Overview of Bacterial Infections

  • How can I get rid of mucus in my throat?

    First treat any underlying conditions, like allergies or a cold. Replace filters in heating and air cooling systems to improve air quality. Drink plenty of water. You can use a humidifier to help clear mucus from your chest and throat. Saline sprays to rinse your nasal passages are another easy way to release sputum.

    Learn More:Saline Nasal Sprays

  • What does sputum from COPD look like?

    The color and look of sputum from COPD can vary from person to person. It may be white and frothy, or it can be mucus-like, cloudy, and greenish, which could indicate you have a bacterial infection. Thicker-than-usual sputum is common with COPD.

    Learn More:Symptoms of Chronic Obstructive Pulmonary Disease (COPD)

  • What causes blood in sputum?

    Common causes for blood found in sputum include: chest infection, bronchiectasis, and even severe nosebleed. Less common causes include pulmonary embolism, lung cancer, and tuberculosis. Even if there are only a few spots of blood in your sputum, reach out to your healthcare provider right away.

    Learn More:Nosebleed: Types, Causes, Treatment

12 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. Pabreja K, Gibson P, Lochrin AJ, Wood L, Baines KJ, Simpson JL. Sputum colour can identify patients with neutrophilic inflammation in asthma. BMJ Open Respir Res. 2017;4(1):e000236. doi:10.1136/bmjresp-2017-000236

  2. Guiot J, Demarche S, Henket M, Paulus V, Graff S, Schleich F, et al. Methodology for Sputum Induction and Laboratory Processing. J Vis Exp. 2017 Dec 17;(130):56612. doi:10.3791/56612

  3. U.S. National Library of Medicine. Routine sputum culture.

  4. Xiang D, Zhang B, Doll D, Shen K, Kloecker G, Freter C. Lung cancer screening: from imaging to biomarker. Biomark Res. 2013;1(1):4. doi:10.1186/2050-7771-1-4

  5. Gershman E, Guthrie R, Swiatek K, Shojaee S. Management of hemoptysis in patients with lung cancer. Ann Transl Med. 2019;7(15):358. doi:10.21037/atm.2019.04.91

  6. Davidson K, Shojaee S. Managing massive hemoptysis. Chest. 2019; doi:10.1016/j.chest.2019.07.012

  7. Budzinski T. Chronic bronchitis. Contemporary Clinic.

  8. Redondo M, Keyt H, Dhar R, Chalmers JD.Global impact of bronchiectasis and cystic fibrosis.Breathe. 2016;12(3):222-235. doi:10.1183/20734735.007516

  9. Shen Y, Huang S, Kang J, et al. Management of airway mucus hypersecretion in chronic airway inflammatory disease: Chinese expert consensus (English edition). Int J Chron Obstruct Pulmon Dis. 2018;13:399-407. doi:10.2147/COPD.S144312

  10. Miravitlles M, Kruesmann F, Haverstock D, Perroncel R, Choudhri SH, Arvis P. Sputum colour and bacteria in chronic bronchitis exacerbations: a pooled analysis. Eur Respir J. 2012;39(6):1354-1360. doi:10.1183/09031936.00042111

  11. Chen K, Pleasants KA, Pleasants RA, et al. A systematic review and meta-analysis of sputum purulence to predict bacterial infection in COPD exacerbations. COPD: Journal of Chronic Obstructive Pulmonary Disease. 2020;17(3):311-317. doi:10.1080/15412555.2020.1766433

  12. National Health Service (NHS). Coughing up blood (blood in phlegm).

Is That Sputum You’re Coughing Up? (2)

By Lynne Eldridge, MD
Lynne Eldrige, MD, is a lung cancer physician, patient advocate, and award-winning author of "Avoiding Cancer One Day at a Time."

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Does coughing up phlegm mean you're almost better? ›

Yes. While the presence of mucus may indicate an underlying issue, coughing up phlegm is a good thing because it helps clear irritants, allergens and infections out of your system.

Do you cough up sputum? ›

Mucus lines and protects sensitive surfaces inside the body, and it helps trap and remove small particles of foreign matter that may pose a threat. Sometimes, the lungs produce too much mucus. The body attempts to expel this excess by coughing it up as sputum or phlegm.

Is it bad to swallow phlegm that you cough up? ›

So, to answer your questions: The phlegm itself isn't toxic or harmful to swallow. Once swallowed, it's digested and absorbed. It isn't recycled intact; your body makes more in the lungs, nose and sinuses. It doesn't prolong your illness or lead to infection or complications in other parts of your body.

How do you cough up sputum for a test? ›

Take a very deep breath and hold the air for 5 seconds. Slowly breathe out. Take another deep breath and cough hard until some sputum comes up into your mouth. Spit the sputum into the plastic cup.

What color phlegm means you're getting better? ›

Summary. Changes in mucus color, from clear to white to yellow to green, are part of the normal course of an illness. It's a sign that your immune system is fighting to get better. Pink, red, orange, or brown snot, on the other hand, is typically not from an illness.

Does coughing up phlegm mean the end of a cold? ›

Colds can make you cough up phlegm as the body fights the infection. But once the infection is gone, the phlegm should also go away. Longer lasting symptoms, or more severe symptoms such as fever or shortness of breath may indicate a bacterial infection (such as pneumonia) that requires an antibiotic.

What is the difference between phlegm and sputum? ›

Sputum, also known as phlegm, is a thick type of mucus made in your lungs. If you have an infection or chronic illness affecting the lungs or airways, it can make you cough up sputum. Sputum is not the same as spit or saliva.

Do you cough up sputum with Covid? ›

A dry cough is one of the most common coronavirus symptoms, but some people may have a cough with phlegm (thick mucus).

Is coughing up sputum from the lungs? ›

Mucus in the lungs is known as phlegm or sputum. It is a common symptom in chronic lung diseases such as COPD (including chronic bronchitis and emphysema), cystic fibrosis, bronchiectasis, NTM lung disease or asthma.

Why does mucus get thicker at the end of a cold? ›

An infection can make mucus thicker and stickier. Infections also lead to inflammation in the mucous membranes that line the nose and the rest of your airway. This can cause certain airway glands to make more mucus. That mucus can get thick with bacteria and cells that arrive to fight the infection.

Why am I coughing up phlegm but not sick? ›

Coughing up phlegm when you don't have a cold could be due to a number of different conditions: a sinus infection, allergies with postnasal drip, pneumonia, smoking, asthma, heartburn, or even some medicines like angiotensin-converting enzyme (ACE) inhibitors for high blood pressure.

What are the stages of phlegm? ›

What to Know and Do When Your Mucus Changes
  • Clear. Thin and clear mucus is normal and healthy.
  • White. Thicker white mucus goes along with feelings of congestion and may be a sign that an infection is starting. ...
  • Light yellow or green. ...
  • Dark yellow or green. ...
  • Pink or red. ...
  • Brown. ...
  • Black.
Dec 5, 2018

How long does sputum last? ›

The Manual of Clinical Microbiology says sputum can be refrigerated for up to 24 hours or kept at room temperature for up to two hours prior to processing for potential pathogens.

How does sputum look like? ›

Gross appearance and other physical characteristics of the sputum are the result of its content of these and other materials. Mucous sputum is clear or translucent and viscous, containing only small numbers of microscopic elements. Purulent sputum is off-white, yellow or green, and opaque.

When is the best time to take a sputum sample? ›

Best time of day to collect sputum is when you first wake. Do not eat, drink or smoke before coughing up sputum from the lungs. Rinse (do not swallow) the mouth with water before sputum is collected to minimize residual food particles, mouthwash, or oral drugs that might contaminate the specimen.

Do you cough up phlegm at the end of Covid? ›

You may find that you are still coughing up phlegm or mucus after an infection with COVID-19 (coronavirus). This is normal after respiratory infections.

How do you tell if a cold is clearing up? ›

Within 7–10 days , people will usually start to recover from a cold. Symptoms begin to ease up, and people will start feeling better. People may also find that they have more energy and are more able to carry out tasks as usual.

How many days is it normal to cough up phlegm? ›

A cough is a reflex action to clear your airways of mucus and irritants such as dust or smoke. It's rarely a sign of anything serious. Most coughs clear up within 3 weeks and don't require any treatment.


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