What Is Sputum?

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 what it looks like. It also discusses what different colors of sputum might indicate.

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.

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. Sputum cytology is not a reliable lung cancer screening tool. However, if cancer cells are found, it can be diagnostic of lung cancer and further tests can determine the location of the cancer.

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 conditions, such as:

• Viral bronchitis
• Viral pneumonia

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. Some of the conditions associated with white phlegm include:

• Viral bronchitis
• Gastroesophageal reflux disease (GERD)
• Chronic obstructive pulmonary disease (COPD)
• Congestive heart failure
  

Dark Yellow/Green Sputum

A type of white blood cells known as neutrophils have a green color to them. These types of white blood cells are attracted to the site of bacterial infections and may cause green sputum. Conditions associated with green sputum include:

• Bacterial bronchitis
• Bacterial pneumonia
• Sinusitis
• Cystic fibrosis

Brown Sputum

Brown sputum often indicates that someone has been inhaling a substance such as air pollution or cigarette smoke. Brown sputum can indicate:

• The presence of tar from smoking
• Exposure to air pollution or heavy smoke from a fire
• Pneumoconiosis (black lung disease)

Sputum may also appear brown or black due to the presence of old blood. This can happen with conditions such as:

• Bacterial bronchitis
• Bacterial pneumonia
• Lung abscess
• Cystic fibrosis

Pink Sputum

Pink sputum contains small amounts of fresh blood and usually indicates a more serious problem, such as:

• Pulmonary edema (sputum may be pink and frothy)
• Tuberculosis
  

Bloody Sputum

Bloody sputum, even just a trace of blood-tinged sputum, should always be evaluated. Bloody sputum (hemoptysis) can be a sign of:

• Lung cancer (Bloody sputum is the first sign in 7% to 35% of cases.)
• Pneumonia
• Pulmonary embolism
• Tuberculosis
• Congestive heart failure

Causes of Increased Sputum

Some conditions that result in increased production of sputum include:

• Chronic bronchitis: Criteria for a diagnosis of chronic bronchitis include 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: A condition caused by a buildup of fluid in the lungs that can be associated with bloody sputum or pink, frothy sputum
• Overproduction of sputum: Can also be caused by smoking and exposure to air pollution
  

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 overproduction of sputum is a normal response.

Tobacco smoke causes paralysis in cilia, the tiny hair-like structures that help move mucus and foreign particles out of your lungs. When the cilia can't move sputum towards your mouth, it accumulates in the airways. Quitting smoking is the best way to combat this problem.

How Do you Flush Out Phlegm?

There are a few things you can try at home that may help you flush phlegm out of your lungs:

• Drink fluids: Fluids help thin mucus so you can clear it more easily. Warm fluids like herbal tea are good choices.
• Salt water gargle: Gargling with salt water may help improve congestion and other cold symptoms.
• Steam: Sleeping with a humidifier in your bedroom can help loosen mucus and make it easier to clear. You can also try inhaling steam from a hot shower or a bowl of hot water.
• Honey: Adding a little honey to your tea may help relieve your symptoms.
• Medication: Medications that may help decrease sputum include aerosol treatments and expectorants. Treatments such as postural drainage may be effective in some situations.

When to See a Healthcare Provider

A cough will usually clear up on its own with rest and self-care. However, you should see your healthcare provider if any of these situations apply to you:

• You have been coughing for longer than two weeks.
• You have a fever.
• Your phlegm isn't clear.
• You are having trouble breathing or you are wheezing.
• Your sputum is pink or red or contains streaks of blood.
  

Summary

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.