Is Phlegm Bad?

Understanding phlegm

The nose, mouth, and throat are lined with a transparent fluid called mucus. A form of mucus, known as phlegm, is produced by the lungs and the lower respiratory tract and acts as an indicator of inflammation of the airways. According to the American Lung Association, it is a common sign of chronic lung conditions.

In healthy airways, oxygenated air flows smoothly through tubes with the assistance of microscopic hairs called cilia that line the airways.1 As irritants are trapped in your airways and helped to be expelled by coughing, mucus plays a crucial part in your lung's immune response. 1You are more resistant to infection as a result.1

Common causes of phlegm

Several medical problems, including the following, might cause an excessive amount of phlegm to be produced:

  • Viral infections such as the common cold
  • Bacterial infections
  • Allergies such as hay fever
  • Acid reflux
  • Acute and chronic bronchitis2
  • Pneumonia
  • Chronic obstructive pulmonary disease (COPD)2
  • Cystic fibrosis
  • Asthma3
  • Whooping cough
  • Emphysema
  • Nontuberculous mycobacteria lung disease
  • Bronchiectasis
  • Sinus infection 
  • COVID-19 (coronavirus)

Additional lifestyle and environmental factors that can cause excessive mucus production include:

  • Chronic persistent pollutant4
  • Mediation such as aspirin-containing products and beta blockers
  • Particular fluids can lead to fluid loss such as alcohol, coffee and tea
  • Smoking5

Signs and symptoms

Coughing usually occurs to expel phlegm, which is frequently accompanied by symptoms including runny nose, sore throat, and nasal congestion. 

Phlegm typically appears to be clear, yellow or green, but in extreme cases, it may be pink, brown or contain blood. The phlegm may sometimes be unusually thick or foamy, and you may find it challenging to cough out enough mucus to open your airways, causing breathing difficulties. 

Types of phlegm

Clear phlegm is normal and is made of water, salt and other cells. An increase in clear phlegm may indicate that a virus or other irritant is being eliminated by your body. Allergic rhinitis (commonly known as hay fever or nasal allergy) is a common cause of clear phlegm.6 

Green or yellow phlegm is probably caused by an infection. The colour of the phlegm alone cannot actually tell you what kind of infection you have e.g. bacterial or viral. If any of your other symptoms worsen, always seek medical attention.

A phlegm that is red or pink may indicate a serious warning sign. Heavy coughing can damage blood vessels in the lungs, which can result in bleeding and red phlegm. Red or pink phlegm, however, can sometimes be brought on by more serious illnesses. If there is blood in your phlegm, it is important to see a doctor as soon as possible as this could be a sign of a serious chronic lung condition which needs to be treated.

Due to the presence of blood and the severe chronic inflammation that results from a chronic lung condition, the phlegm can be brown. The bacteria inside the lungs gradually alter the texture and appearance of phlegm. If you have a persistent lung condition, it might be normal for you to notice that you have brown phlegm.

Is there such a thing as “good phlegm”? 

A mucus that is thin and clear is healthy and typical. Phlegm that is white, and thicker and causes feelings of congestion could be early signs of an infection.

Effects of phlegm in our body

Although phlegm by itself is not harmful, it can obstruct the airways when it is present in significant amounts. 

Risks of having phlegm

Mucus is used to remove pathogens from the body. Although this is beneficial to our bodies, if we produce too much mucus it can lead to infections and difficulties in breathing.


​Phlegm may accumulate in your throat and lungs, blocking your airways and, in severe conditions, making it difficult to breathe or swallow.

Treatment and prevention

  1. Drinking water - This can help you to stay hydrated and improve the congestion in your body by allowing the phlegm to move easily
  2. Nasal saline spray - These can help relieve congestion
  3. Gargling with salt water - salt water is also beneficial if you have a sore throat as it can relief the irritant symptoms of it as well as allowing phlegm to move more easily by making it loose
  4. Humidifier or steam - Congested mucus may better drain with the use of steam and humidifiers7 
  5. Postural drainage - Postural drainage is a method that entails lying or sitting in specific positions to allow gravity to remove secretions from your airways.
  6. Controlled coughing - This helps to move and loosen mucus. You can find exercises here.
  7. Mucolytics - Mucolytics are medications that help patients with COPD, cystic fibrosis, and bronchiectasis manage mucus hypersecretion and related effects, such as recurring infections.8
  8. Expectorants - A cough suppressant that works to help you clear phlegm from your airways.9
  9. Chest Physiotherapy (CPT) - Research has shown that a form of physiotherapy known as chest physical therapy aids in the removal of mucus and other airway secretions to improve the passage of air into the lungs.10
  10. Quit smoking - Research has shown that tobacco smoke causes mucus overproduction so quitting cigarettes could help to decrease the amount of mucus in your body.5
  11. Vaccinations - Getting your vaccinations for diseases such as influenza (flu) and COVID-19 could help prevent the symptoms of phlegm and congestion

When to contact a doctor

Normal mucus production should resume once a physician can identify and address the underlying issue. Therefore, it is important to see a doctor if your phlegm production is abnormal so you can receive the correct treatment for better health.


A cough or phlegm might seem minor and normal but a persistent cough or phlegm with blood could be a sign that you have a serious condition that needs medical attention and should not be ignored. When your health is at risk, the best step would to be consult a doctor.


  1. NT Contributor. The physiology of mucus and sputum production in the respiratory system | Nursing Times [Internet]. Nursing Times. 2003 [cited 2022 Oct 3]. Available from:
  2. Poole P, Chong J, Cates CJ. Mucolytic agents versus placebo for chronic bronchitis or chronic obstructive pulmonary disease. Cochrane Database of Systematic Reviews [Internet]. 2015 Jul 29 [cited 2022 Oct 3]; Available from:
  3. Dunican EM, Elicker BM, Gierada DS, Nagle SK, Schiebler ML, Newell JD, et al. Mucus plugs in patients with asthma linked to eosinophilia and airflow obstruction. Journal of Clinical Investigation [Internet]. 2018 Feb 5 [cited 2022 Oct 3];128(3):997–1009. Available from:
  4. Marczynski M, Lieleg O. Forgotten but not gone: Particulate matter as contaminations of mucosal systems. Biophysics Reviews [Internet]. 2021 Sep [cited 2022 Oct 6];2(3):031302. Available from:
  5. Strzelak A, Ratajczak A, Adamiec A, Feleszko W. Tobacco Smoke Induces and Alters Immune Responses in the Lung Triggering Inflammation, Allergy, Asthma and Other Lung Diseases: A Mechanistic Review. International Journal of Environmental Research and Public Health [Internet]. 2018 May 21 [cited 2022 Oct 3];15(5):1033. Available from:
  6. Shweta Akhouri, House SA. Allergic Rhinitis [Internet]. StatPearls Publishing; 2022 [cited 2022 Oct 6]. Available from:
  7. Singh M, Singh M, Jaiswal N, Chauhan A. Heated, humidified air for the common cold. Cochrane Database of Systematic Reviews [Internet]. 2017 Aug 29 [cited 2022 Oct 6];2017(8). Available from:
  8. Gupta R, Wadhwa R. Mucolytic Medications [Internet]. StatPearls Publishing; 2022 [cited 2022 Oct 4]. Available from:
  9. Rubin BK. The pharmacologic approach to airway clearance: Mucoactive agents. Paediatric Respiratory Reviews [Internet]. 2006 Jan [cited 2022 Oct 6];7:S215–9. Available from:
  10. Selvia David Richard, Heri Ariyanto, Setiawan H. Implementation of Evidence-Based Nursing for Expelling Sputum in Tuberculosis Patients with Chest Physiotherapy and Effective Coughing Exercises: A Case Study. International Journal of Nursing and Health Services (IJNHS) [Internet]. 2022 [cited 2022 Oct 4];5(3):259–66. Available from:
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

Get our health newsletter

Get daily health and wellness advice from our medical team.
Your privacy is important to us. Any information you provide to this website may be placed by us on our servers. If you do not agree do not provide the information.

Dechante Johnson

BSc Neuroscience, University of Exeter, England

Dechante is a 3rd year neuroscience student at the University of Exeter. She has recently carried out research at the University of Western Ontario, Canada where she investigated the "Sensory filtering in Autisic Models". Dechante's main interests are clinical neuroscience, behavioural sciences, health policy and understanding the inequities in healthcare. She is particularly interested in using interdisciplinary biomedical research to answer complex questions and global problems in medicine and health. Dechante is passionate about medical communications and believes that patients should be fully aware of the options available to them and give the public complex information about health into simplistic terms. presents all health information in line with our terms and conditions. It is essential to understand that the medical information available on our platform is not intended to substitute the relationship between a patient and their physician or doctor, as well as any medical guidance they offer. Always consult with a healthcare professional before making any decisions based on the information found on our website.
Klarity is a citizen-centric health data management platform that enables citizens to securely access, control and share their own health data. Klarity Health Library aims to provide clear and evidence-based health and wellness related informative articles. 
Klarity / Managed Self Ltd
Alum House
5 Alum Chine Road
Westbourne Bournemouth BH4 8DT
VAT Number: 362 5758 74
Company Number: 10696687

Phone Number:

 +44 20 3239 9818