Phlegm color can provide important information about what is going on inside your body. The color of phlegm can indicate infection, inflammation, or a variety of lung conditions. Understanding what different phlegm colors may signify can help guide conversations with your doctor and determine appropriate treatments. Here is an overview of the most common phlegm colors and what they typically mean:
Clear Phlegm
Clear phlegm is usually a normal and healthy sign. Clear mucus indicates that there is no pus or blood in the mucus, and the secretions are produced in normal amounts to help keep the airways moist. Some common causes of clear phlegm include:
- The common cold
- Allergies
- Irritants like smoke or dust
- Weather changes
Clear phlegm is not usually a sign of infection. However, if it is produced in excessive amounts or is very thick and difficult to cough up, it could indicate:
- Chronic bronchitis
- Sinusitis
- Asthma
White Phlegm
White phlegm indicates that mucus has thickened and taken on a cloudy or milky appearance. Some potential causes include:
- Viral infection – The early stages of a cold or flu virus often cause white phlegm in the nose and throat.
- Bacterial infection – Thick, cloudy phlegm may indicate the start of a bacterial infection like strep throat, pneumonia, or bronchitis.
- Allergies – Allergic reactions can trigger excess mucus production and white phlegm.
- Asthma – Asthma attacks or flare ups cause swelling in the airways which results in increased mucus production.
- Smoking cigarettes – The toxins in cigarette smoke increase mucus production and can give phlegm a white color.
See your doctor if white phlegm lasts longer than a week or two to determine if antibiotics are needed to treat an infection. Using a humidifier and staying hydrated may also help loosen up thickened mucus secretions.
Yellow Phlegm
Yellow or golden colored phlegm indicates the presence of pus and white blood cells in the mucus. Pus generally signals a bacterial infection in the respiratory system, such as:
- Acute bronchitis
- Pneumonia
- Chest cold
- Flare up of chronic bronchitis
- Sinusitis
- Tonsillitis
The immune system sends white blood cells to the site of a bacterial infection, and the mix of cell debris and bacteria produces yellow mucus. Coughing up yellow phlegm is an expected part of healing from these illnesses. However, yellow phlegm that lasts for more than 2 weeks may indicate an underlying lung condition or untreated infection. See your physician in that case.
Green Phlegm
Green phlegm usually indicates an active infection in the lower respiratory tract. The green color comes from white blood cells produced in response to a lung infection. Some specific conditions associated with green phlegm include:
- Bacterial pneumonia – Pneumonia often causes green phlegm as the neutrophils attack the bacteria.
- Chest cold
- Abscessed tonsils
- Early stage of bronchitis
- Sinusitis with post-nasal drip into the lungs
Darker green phlegm can indicate a long-standing infection. Olive green or mustard colored phlegm may signal a sinus infection as well. See a doctor if green mucus persists more than 10 days or you have a fever over 101°F.
Orange Phlegm
Orange phlegm is uncommon but can sometimes occur with respiratory infections. Possible causes include:
- Pneumonia – Orange mucus can appear after the first few days of pneumonia as white blood cells attack lung tissue.
- Infection related bronchitis
- Fungal sinus infection
Orange phlegm indicates there is damage and inflammation in the respiratory system. See a doctor right away if you cough up thick, gelatinous orange mucus, especially if accompanied by chest pain or breathing difficulties. This can indicate a health emergency like pulmonary embolism.
Red or Pink Phlegm
Red tinged phlegm is generally an alarming sign that requires prompt medical evaluation. Red mucus contains blood, indicating some type of bleeding in the respiratory tract:
- Pneumonia – Severe pneumonia can cause extensive inflammation and irritation of the lungs, leading to bleeding.
- Tuberculosis – TB damages the lungs and may result in bloody phlegm.
- Lung cancer – Tumors in the lungs often bleed into the airways.
- Pulmonary edema – Fluid buildup in the lungs allows red blood cells to enter the airways.
- Bronchiectasis – Damage and widening of the airways can lead to bloody mucus.
Pink phlegm is concerning but less alarming than frank blood. It may develop from small amounts of bleeding or mix of blood and normal mucus secretions. Causes include:
- Viral or bacterial infection
- Asthma attack
- Bronchitis
- Smoking
See a doctor right away if you cough up phlegm with red streaks or a pink frothy consistency. This should be evaluated promptly to identify the cause and determine if treatment is needed.
Brown Phlegm
Brown phlegm contains old blood and indicates past bleeding in the respiratory system. The most common causes are:
- Recent coughing of bloody mucus that is now brown and drying out
- Bronchitis
- Smoking
- Environmental inhalation
Brown phlegm is usually not an emergency. However, if the phlegm is thick, foul smelling, or associated with symptoms like chest pain, get medical assessment to rule out lung abscess or other complications.
Black Phlegm
Black phlegm can have several possible causes:
- Coal dust inhalation – Working around coal dust without protective gear.
- Smoking tobacco products – Tar from smoking can stain mucus black.
- Fungal infection – Aspergillus fungus can cause green-black or black mucus.
- Environmental pollution – Inhaling smoke, ash, or dust may tint phlegm black.
Black mucus is generally harmless if it happens occasionally. But see your doctor if black phlegm develops frequently or you work around airborne pollutants and toxins. Long term inhalation of coal dust can lead to black lung disease.
Gray Phlegm
Gray or dark gray phlegm can occur from:
- Smoking – Tobacco smoke contains many toxins that both irritate and pigment the mucus.
- Chemical fume exposure – Industrial chemicals may tint mucus gray.
- Chest infections – Very thick, dried out mucus can take on a dark gray hue.
- Air pollution – Particulate matter in polluted air can make phlegm appear dark gray.
Evaluate any breathing troubles or illnesses related to gray mucus. See an occupational health doctor if it occurs at work. Long term inhalation of irritants may lead to lung disease.
Blue Phlegm
True blue phlegm is extremely rare and always abnormal. Possible causes include:
- Pseudomonas aeruginosa infection – This bacteria can raise pH and cause blue-green phlegm.
- Exposure to dyes – Certain industrial dyes or heavy metals like lead or copper can tint mucus blue.
- Methylene blue dye – This medical dye used in some surgeries can temporarily turn phlegm blue.
- Genetic metabolic disorder – Very rare disorders can lead to abnormal buildup of blue pigments.
Blue phlegm indicates a potentially serious underlying problem. Seek medical evaluation if you notice blue tinged mucus when coughing or blowing your nose.
What does it mean if phlegm is thick and sticky?
Thick, glue-like phlegm can be a sign of excess mucus in the lungs. Some potential causes include:
- Viral illness
- Bacterial infection
- Asthma
- COPD
- Cystic fibrosis
- Bronchiectasis
Thick phlegm often occurs with inflammatory lung conditions that increase mucus secretion while impairing the normal mucus clearance mechanisms. See your doctor if sticky phlegm persists beyond a week or two.
What does it mean if phlegm is foul smelling?
Foul smelling phlegm is often a sign of lung abscess or chronic post-nasal drip. A lung abscess can form after untreated pneumonia and result in pus trapped in the lungs. This infected material may smell bad when coughed up. Chronic sinus inflammation from allergies or other issues can also lead to mucus dripping down the throat, which may have an unpleasant odor. Seeing a doctor for foul smelling mucus can help diagnose and treat any underlying infection or chronic condition.
What does bloody phlegm mean?
Bloody phlegm or phlegm with red streaks signals bleeding somewhere in the lungs or airways. This requires prompt medical evaluation to determine the cause. Possible reasons for bloody sputum include:
- Lung cancer
- Pneumonia
- Tuberculosis
- Pulmonary edema
- Lung abscess
Smoking, bronchitis, and lung damage can also sometimes lead to small amounts of blood in the sputum. Seek emergency care for large amounts of bloody phlegm or any difficulty breathing.
What does yellow phlegm mean?
Yellow or greenish phlegm usually indicates the presence of pus and a bacterial infection in the lower airways. Some examples include:
- Bronchitis
- Pneumonia
- Abscessed tonsils
- Sinusitis
The immune system sends neutrophils to attack the infection, and the mix of pus and debris creates yellow or green mucus. See a doctor if it lasts more than 10 days or comes with a fever over 101°F.
What does it mean if phlegm is brown?
Brown phlegm most often occurs from old blood pigment turning the mucus brown. Coughing up brown mucus could happen from:
- Past bloody phlegm that is now drying out
- Smoking tobacco products
- Environmental inhalation
- Bronchitis
Evaluate any other symptoms that occur with brown phlegm. Seek medical advice if it is thick, foul smelling, or associated with difficulty breathing.
What does it mean if phlegm is black?
Black phlegm has several possible causes, including:
- Inhaling coal dust
- Smoking tobacco products
- Fungal infection
- Environmental pollution
Occasional black phlegm is usually harmless. However, see a doctor if it develops frequently or you work around pollutants. Chronic exposure can lead to serious lung conditions over time.
Conclusion
The color of phlegm can provide clues about what is going on inside the body. Clear phlegm is normal, while red, brown, or black phlegm indicates bleeding. Yellow or green mucus signals infection. Orange, gray, or foul smelling phlegm can point to lung damage or chronic illness.
Seeing a physician promptly is recommended if unusual colored phlegm lasts more than a couple weeks or comes with other concerning symptoms. Proper treatment can deal with the underlying cause and help restore normal clear phlegm. Paying attention to sputum color changes along with other respiratory symptoms allows for earlier diagnosis and management of many lung conditions.