Dr. Nabi Darya Vali (AIIMS)MBBS

November 01, 2018

March 06, 2020



Phlegm is a thick, slimy, fluid produced by the cells of the linings of the lungs and upper airways. It is produced in the body as one of the defence mechanisms and is medically termed as mucus. But, when a person is healthy, the mucus is thin in consistency; hence, it is unnoticeable. During certain illnesses, mucus thickens to trap dust particles and infectious agents such as bacteria. Phlegm may have an unusual odour and colour to it in the case of an underlying disease and needs to be investigated. It might be produced in excess in illnesses such as common cold, upper respiratory tract infection, chronic obstructive pulmonary (lung) disease (COPD), allergy, asthma, pneumonia, and lung cancer. Diagnosis of abnormal phlegm is usually done by taking a chest X-ray or CT scan, microscopic and culture examination of the phlegm along with some blood tests to confirm the same. Treatment protocols depend upon the underlying cause and vary from person to person. Prevention of phlegm is not possible as it is a naturally produced fluid in the respiratory tract. 

What is phlegm

Phlegm is a thick mucus secreted in more than normal amounts by the cells of the lungs and the upper respiratory tract. It becomes noticeable when a person is sick because mucus is thickened and produced in abnormally high amounts during illnesses. Chronic lung diseases are responsible for 4% of the global burden of chronic illnesses. A chronic cough affects a person’s quality of life and is an economic burden. It is reported that more than 10 billion dollars are spent on the treatment of a cough globally. There is limited data on how lung diseases affect the Indian population and its economy. In this article, we will discuss abnormal phlegm only. 

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Phlegm symptoms

Excess or abnormal phlegm production indicates the presence of an underlying illness. Normally, phlegm (sputum) is expelled from the body via coughing. Symptoms that may accompany abnormal phlegm production include: 

Phlegm causes & risk factors


Causes of phlegm are:

  • Upper respiratory infections (URTIs) 
    URTI are mostly viral infections of the upper part of the respiratory tract (involving the nose, sinuses, and the throat), which are self-limiting, i.e., their symptoms often get better without any treatment. There are over 100 types of rhinoviruses (viruses affecting the nose) that can cause a common cold. Other viruses like influenza, parainfluenza, enteroviruses, coronaviruses, and others also cause a common cold. These outbreaks are commonly seen in winter and spring and are spread via direct contact with an infected individual. Symptoms often begin within 24 to 72 hours of viral exposure with irritation in the nose and sore throat and are later followed by sneezing, runny nose, and cough. In some people, the nasal secretions become yellow in colour that does not indicate a bacterial infection. This leads to a cough along with phlegm production, which may last for almost two weeks.
  • Chronic obstructive pulmonary disease (COPD) 
    Chronic obstructive pulmonary disease (COPD) is a group of progressive lung diseases that cause breathing difficulties. COPD includes the following respiratory tract diseases- chronic bronchitis, emphysema, and irreversible asthma.
    • Emphysema
      It causes damage to the lung alveoli, which are tiny air sacs that expand and contract during breathing enabling exchange of gases during respiration. In emphysema, the lung alveoli become over-expanded (over-inflation) leading to difficulties in the exchange of gases. Over time, the alveoli rupture and reduce the lung surface area, causing less oxygen to reach the blood. In emphysema, as the alveoli are damaged, old air is trapped leaving no room for fresh air to enter. A person may have emphysema for several years without any symptoms. The main sign of emphysema is breathlessness, which has a gradual onset and worsens as the disease progresses. People with emphysema should avoid activities that lead to shortness of breath. In advanced cases, shortness of breath may be seen even at rest.
    • Chronic bronchitis
      It is defined as a cough with expectoration (sputum production) that lasts for more than three months in a year with recurring bouts for two or more years. In chronic bronchitis, the airways within the lungs are inflamed. The cilia are tiny hair-like structures that line these airways and help to remove mucus out of the lungs, keeping the lungs clean and healthy. When these cilia are damaged, the mucus settles in the airways making it difficult to cough the mucus out. This restricts the air flow making it difficult to breathe. Such individuals produce phlegm with a cough, which may be white or yellowish grey in colour. In some cases, the phlegm may be green due to the presence of bacterial infection or may even show streaks of blood. Individuals with chronic bronchitis also complain of chest pain and breathlessness. In an acute attack, an individual may also have a headache, fever with chills along with fatigue.
    • Non-reversible asthma 
      It is another type COPD characterized by episodes of a cough, sputum production, wheezing and shortness of breath. Here the phlegm produced is typically white or grey. It occurs due to an exaggerated response of the airways to common stimuli like cold air, pollen, animal dander, and others. It is termed as non-reversible as despite medications the narrowing of the airways cannot be fully reversed, as is the case with reversible asthma.  Episodes need to be managed as and when they arise.
  • Post-nasal drip or discharge
    Post-nasal discharge occurs when the excess mucus is felt running down the back of the nose and the throat, especially while lying down. Normally, the mucus from the nose is not felt as it is very thin and gets mixed with the saliva as it goes down the throat. Mucus is produced daily by the glands in the nose, throat, stomach, and intestines. The nose contributes the maximum of daily total mucus secretion. This mucus moistens these parts and traps foreign particles and bacteria. During an illness, the mucus thickens or is secreted more than normal and is felt by the person. Post-nasal drip can be caused due to the following reasons:
    • Cold or flu.
    • Change of weather.
    • Dry air or dry weather.
    • Allergy.
    • Sinusitis.
    • Deviated nasal septum.
    • A foreign object stuck in the nose.
    • Medications for high blood pressure, contraception, and more.
    • Perfumes, smoke, and other chemical irritants.

A person with a post-nasal drip constantly feels an urge to clear the throat due to a sensation of mucus being stuck in the throat. It may also cause a cough, which is worse at night or while lying on the bed. Excess mucus can also lead to soreness and redness in the throat. In some individuals, the mucus may block the ear canal leading to an infection.

  • Bronchiectasis
    In this condition, the airways are damaged and become wide and scarred. Bronchiectasis occurs by severe infections that stop the airways from removing mucus completely. Due to the accumulation of mucus in the airways and lung tissue leading to the development of bacteria and other infectious agents. As a result, there is a formation of small cavities that are filled with pus. With every infection, the airway damage increases leading to less transport of oxygen to the body organs. Lung diseases that can progress to bronchiectasis include:
  • Tuberculosis.
  • Pneumonia.
  • Fungal infections.
  • Whooping cough due to Bordetella pertussis, a type of bacteria.
  • Blockage of airway due to aspiration of the broken part of a toy or peanut by a child.
  • Non-cancerous tumours.

Individuals with bronchiectasis present with symptoms like a chronic cough that lasts for years along with an excess production of phlegm that contains trapped particles and pus. The person may also experience shortness of breath with wheezing and chest pain. Advanced bronchiectasis may lead to complications such as respiratory or even heart failure.

  • Gastrointestinal reflux disease (GERD)
    In GERD, the stomach acid rises back into the throat and the oesophagus (food pipe). This acid reflux causes an irritation in the lining of the oesophagus. At the lower end of the oesophagus, there is a band of muscles known as the lower oesophageal sphincter, which opens and closes to allow foods and liquids into the stomach. After the food enters the stomach, the sphincter closes. If the sphincter weakens, it will open even when there is no intake of foods or liquids causing the contents of the stomach to flow back into the oesophagus. Along with foods and liquids, stomach acid is also regurgitated into the oesophagus causing an irritation of the oesophageal tissues. This irritation activates the cough reflex centres in the brain causing coughing, especially during the night. Most people have experienced mild forms of GERD from time to time. The classic symptoms of GERD include chest pain along with a burning sensation, which is worse after meals or at night time, difficulty in swallowing, and regurgitation of foods and liquids. Along with the classic GERD symptoms, people may also have a chronic cough with phlegm and irritation in the larynx along with disturbed sleep. Factors that worsen acid reflux are:
    • Eating heavy meals.
    • Eating very late at night.
    • Smoking.
    • Alcohol, coffee.
    • Aspirin. 
  • Pneumonia
    In pneumonia, the air sacs, which are known as alveoli, are infected. The infection may be viral, bacterial, or fungal in origin. Symptoms may be as mild as an irritating cough or there may be blood-stained phlegm, fever, chills, and breathlessness. Pneumonia can lead to serious complications in children under the age of 5 years and adults over 65 years of age. Individuals who have diabetes, heart failure or a weak immune system due to AIDS or cancer therapy are at an increased risk of developing pneumonia.
  • Other causes of phlegm are
    • Foreign body in the airways e.g., toy, dust particles, mineral particles from mining.
    • Bronchiolitis (inflammation of the smaller airways in the lungs).
    • Lung cancer.
    • Sarcoidosis (enlargement of the lymph nodes leading to the development of inflammatory tissue produced in response to infections).

Risk factors

  • Smoking
    The most important risk factor is smoking. It is reported that almost 75 % of people with COPD have a history of smoking. People who have a family history of COPD have a higher chance of developing it. Even exposure to passive smoke can cause coughing and lung diseases that produce excess phlegm.
  • Age
    Children are more susceptible to contracting respiratory infections due to an incompletely developed immune system. Adults over  60 years of age are also prone to lung infections.
  • Environment
    Individuals who are exposed to fumes, pollutants, smoke, irritants, chemicals, insecticides, etc. are more prone to developing lung infections and breathing problems.
  • Health conditions
    Individuals who are overweight, obese, or have heart diseases and diabetes, are at an increased risk of developing infectious diseases like pneumonia, bronchitis among others.
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Prevention of Phlegm

  • Quit smoking
    Quit smoking as soon as possible. Consider joining a support group or discuss with doctors and specialists to learn about the products and programs to help quit smoking. Involve family members and friends as well.
  • Avoid exposue to irritants
    Avoid exposure to smoke, dust, and pollution.
  • Healthy diet and exercise
    Include a nutritious diet of fresh fruits, juices and vegetables in the daily diet to build immunity. Do daily physical activity like walking, jogging, swimming, running, sports to maintain good health and keep illnesses away.

Diagnosis of Phlegm

Diagnosis of the underlying cause of phlegm is based on:

  • Medical history
    A complete patient medical history is obtained to determine the underlying cause of phlegm. The person will be asked to reveal information regarding the onset of phlegm production, type of a cough along with other symptoms like fever, chest pain, and breathlessness for further diagnosis. A complete physical examination will also be performed to correlate the information given by the individual.
  • Laboratory tests
    Blood tests such as a complete blood count (CBC), erythrocyte sedimentation rate (ESR), etc., can reveal the presence of an infection. Sputum examination and culture may be performed to identify the type of bacteria causing the infection.
  • Liver function tests
    These are simple lung tests to determine the amount of air the lungs can hold. These tests can help to diagnose underlying diseases such as asthma, bronchitis, emphysema, and so forth.
  • Imaging tests
    Investigations like a chest X-rays, CT scan, and MRI scan can help to diagnose pneumonia, asthma, lung cancer, tumour. An X-ray of the nasal sinuses can also help in diagnosing sinus infections.
  • Endoscopy
    In certain cases where the above tests do not confirm the diagnosis, special bronchoscopy tests will be considered. A bronchoscope (tube-like structure) is passed into the lungs to look for abnormalities, tumours, masses, and other causes that can cause phlegm.

Phlegm treatment

The treatment of phlegm depends on the underlying cause. In some cases, there are several causes of phlegm. Treatment plan includes:

  • Medications
    Doctors prescribe antimicrobials for infections, anti-allergic medicines for allergies, and anti-inflammatory medicines for asthma. Antacids are prescribed to treat acid reflux. If the exact cause cannot be determined, cough suppressants are prescribed to relieve symptoms.
  • Chest physiotherapy
    In certain conditions like bronchiectasis, chest physiotherapy aids better clearance of phlegm and improves the overall comfort while breathing by increasing the functioning of the muscles associated with breathing.

Lifestyle management

  • Drink plenty of fluids, hot soups, juices to make the phlegm thinner.
  • Cough drops and lozenges help to ease irritation in the throat.
  • Use steam to relieve nasal congestion.
  • Avoid smoking or exposure to passive smoke.
  • Wash hands before and after every meal and after touching the mouth/nose.
  • Yoga or deep breathing techniques can help clear excess phlegm buildup.
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Phlegm prognosis and complications


Results of phlegm depend on the underlying cause. Acute infections like common cold are self-limiting and have excellent outcomes. The results of diseases like COPD and lung cancer depend on the stage and severity of symptoms.


Complications of phlegm depend on the underlying cause. They may include:

  • COPD.
  • Lung abscess.
  • Lung failure.
  • Pulmonary hypertension (increased blood pressure in the blood vessels of the lungs). 
  • Heart failure.
  • Sepsis (the spread of infection from its site into the bloodstream). 
  • Pleurisy and pleural effusion (inflammation and infection of the lining of the lungs).
  • Empyema (infection of the fluid between the two thin membranes that surround the lungs).


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  4. MSDmannual Professional version [internet].Common Cold. Merck Sharp & Dohme Corp. Merck & Co., Inc., Kenilworth, NJ, USA
  5. COPD Foundation [Internet] US; Understanding COPD
  6. National Heart, Lung, and Blood Institute [Internet]: U.S. Department of Health and Human Services; Bronchiectasis
  7. Irwin RS. Chronic cough due to gastroesophageal reflux disease: ACCP evidence-based clinical practice guidelines. Chest. 2006 Jan 1;129(1):80S-94S. PMID: 16428697
  8. National Heart, Lung, and Blood Institute [Internet]: U.S. Department of Health and Human Services; Pneumonia
  9. Center for Disease Control and Prevention [internet], Atlanta (GA): US Department of Health and Human Services; Smoking and COPD

Medicines for Phlegm

Medicines listed below are available for Phlegm. Please note that you should not take any medicines without doctor consultation. Taking any medicine without doctor's consultation can cause serious problems.

Lab Tests recommended for Phlegm

Number of tests are available for Phlegm. We have listed commonly prescribed tests below:

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