Phlegm is a type of mucus produced by tissues in the respiratory system (the lungs, bronchi, throat, and windpipe). It’s a sticky, gooey substance that actually protects your airways from viruses, bacteria, allergens, and other pollutants we often inhale. Your body produces about 1.5 quarts of mucus (including phlegm) daily. In other words, you make about as much mucus in a day as it takes to fill a medium-sized ice cream tub. Gross, right?

Your body produces phlegm naturally, but infections and irritants can cause your respiratory tract to overproduce this mucus, often accompanied by symptoms like coughing, wheezing, and shortness of breath. You’ll also probably notice that your phlegm is... a little colorful. This may be a sign of infection and illness. In this blog article, we’ll take a look at what causes your body to make too much phlegm and what the different colors of this natural mucus might mean for your health.

What is Phlegm?

First things first: phlegm, also known as sputum, is a thin, clear mucus produced by the respiratory system. It serves several purposes.

The primary role of phlegm is to protect the airways against irritants and infection by trapping viruses, bacteria, protozoa, and other contaminants. Your body naturally expels this viscous liquid along with the bad stuff it’s trapped.

Your body produces phlegm naturally. In some instances, however, when your body is triggered to fight an infection or foreign substance, the membranes that produce phlegm may overproduce phlegm. This can be in response to health conditions such as:

• Asthma
  
• Chronic lung diseases like chronic obstructive pulmonary disease (COPD), chronic bronchitis, or cystic fibrosis
  
• Exposure to allergens and seasonal allergies
  
• Respiratory infections like the common cold or influenza (the flu)
  
• Acid reflux (GERD)
  
  

There are many reasons for your body to produce excess phlegm, though these are among the most common. An overproduction of phlegm, coupled with changes in the mucus’ color, may signal a condition that requires medical treatment.

The Colors of Phlegm & What They Mean

Phlegm color, as noted above, is a good indicator that something is wrong with your respiratory system. There are several myths and misunderstandings about the correlation between color changes and its possible cause. While changes in mucus color can help provide information about your wellness, an altered hue should not be used to diagnose anything definitively.

That being said, here is what the shade of your sputum might mean:

Clear Phlegm: Clear phlegm is normal. It is made up of water, immune system cells, and salts. Clear phlegm most likely means that you are healthy and not experiencing any medical condition affecting the respiratory tract.

White Phlegm: White mucus often indicates a viral infection, a bacterial infection, or an allergic reaction. The color change often indicates your body is reacting to something-–be it infectious or simply the body trying to combat allergens or a chronic process like COPD. It doesn’t necessarily mean you have an infection that would benefit from antibiotics.

Green or Yellow Phlegm: Green phlegm or yellow phlegm is also often a sign of an infection. When your body fights off an infection, such as a bacterial or viral respiratory infection, your immune system sends white blood cells to the site of infection to combat the invading pathogens. These white blood cells contain enzymes that help destroy bacteria and other foreign substances. As these cells break down and die, they release a greenish enzyme called myeloperoxidase, which can cause yellow or green mucus.

Brown or Black Phlegm: Black or brown phlegm may indicate different conditions or causes. Smoking tobacco is among the most common causes of black or brown phlegm. The tar and chemicals in tobacco smoke can accumulate in the respiratory tract and lungs over time. As a result, the phlegm produced by smokers may have a dark color, reflecting the presence of these toxins.

Similarly, exposure to environmental pollutants, such as heavy air pollution or particulate matter, can lead to inhaling airborne particles. These particles may get trapped in the mucus lining the respiratory tract and cause it to darken over time, particularly relevant in urban areas with high pollution levels.

Dark-colored phlegm may also be caused by a fungal infection, such as aspergillosis. Aspergillosis is an infection caused by Aspergillus, a common mold found indoors and outdoors.

If you produce black phlegm, you should seek medical attention right away, especially if you have a weakened immune system. Dark-colored mucus indicates a potentially serious health concern that requires medical advice and treatment as soon as possible.

Pink or Red Phlegm: Phlegm that is pinkish or red in hue indicates that blood is in the mucus. Many factors could cause this.

You might experience pink phlegm due to a nosebleed that seeps into the post-nasal drip. You may also experience reddish phlegm caused by health conditions such as:

• Pneumonia
  
• Tuberculosis
  
• Bronchiectasis (damaged and swollen airways)
  
• Congestive heart failure
  
• Lung cancer
  
• Pulmonary embolism (a blockage in the pulmonary arteries)
  
  

When to See a Health Care Provider

Phlegm is natural. You have phlegm in your body right now. Many mild illnesses, such as a common cold or a sinus infection, can cause excess phlegm, though these cases can usually be handled through home remedies and over-the-counter treatment.

You should contact a health care provider if you experience phlegm buildup lasting more than several days or affecting your daily activities. White, clear, green, or yellow mucus is common with mild illnesses, and you are usually safe to wait a few days before making an appointment to see a health care provider. However, you should seek medical attention if your phlegm production is accompanied by other symptoms such as:

• Difficulty breathing
  
• Chest pain
  
• Sore throat
  
• High fever
  
  

You should immediately seek medical attention if you notice any brown, red, or black phlegm. Dark-colored phlegm is a sign of a serious infection or a severe underlying condition. Do not wait to see if it goes away; contact a health care provider to get care immediately.

Getting Rid of Phlegm

Most cases of phlegm buildup can be treated with at-home remedies and over-the-counter medication.

Commonly used home remedies for congestion and phlegm include:

• Use a humidifier
  
• Drink plenty of fluids
  
• Get plenty of rest
  
• Rinse your nasal passages with a saline solution or Neti pot
  
• Use eucalyptus oils in a diffuser to inhale or apply eucalyptus essential oils as a balm for chest congestion
  
  

Decongestants: Decongestants are the most commonly used medication for congestion. These drugs are widely available as oral tablets or capsules, nasal sprays, or liquid solutions meant to be ingested orally. They work by narrowing blood vessels in the nasal passages, which reduces inflammation and mucus production.

Using decongestants for a limited amount of time is important, as extended use can lead to worsening symptoms.

You can find OTC decongestants in generic or brand-name versions. Commonly used decongestants include pseudoephedrine (Sudafed)and oxymetazoline (Afrin).

Expectorants: An expectorant is a medication that clears excess mucus and phlegm from the airways, primarily the respiratory tract. It works by thinning and loosening the mucus, making it easier for the body to expel it through coughing.

Guaifenesin is the most commonly used OTC expectorant. It is available under its generic name (guaifenesin) or a brand name like Mucinex or Robitussin. Many OTC cough, cold, and flu medications also contain guaifenesin.

Phlegm is a natural and valuable substance your body produces to protect itself. Thick or discolored mucus does not necessarily constitute a severe medical condition. Persistent thick mucus, or dark-colored mucus, indicates a problem that requires medical attention. If your phlegm does not go away within a few days, or if it is red, brown, or black, seek medical attention right away.

Looking for more information? Read more about how to get rid of mucus and phlegm or book an online doctor appointment on Sesame to discuss your symptoms and possible treatment options with a licensed health care provider today.

Sources:

• Altiner, A., Wilm, S., Däubener, W., Bormann, C., Pentzek, M., Abholz, H. H., & Scherer, M. (2009). Sputum colour for diagnosis of a bacterial infection in patients with acute cough. Scandinavian journal of primary health care, 27(2), 70–73. https://doi.org
  
• National Institutes of Health (n.d.). Marvels of Mucus and Phlegm. News in Health. newsinhealth.nih.gov
  
• Parsons, J., MD (2017, December 22). What does the color of phlegm mean? Wexner Medical Center. wexnermedical.osu.edu
  
• Shen F, Sergi C. Sputum Analysis. [Updated 2023 Feb 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. https://www.ncbi.nlm.nih.gov