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Phlegm is a type of mucus that is produced in the lungs and nearby lower respiratory tract airways. This kind of mucus has a crucial role in preventing germs and materials from entering the airways and lungs and potentially causing an infection.

Other areas of the body, including the upper respiratory tract (nose, mouth, and throat) and gastrointestinal tract (gut) also secrete mucus.

Typically, mucus is clear and thin and not noticeable at all. When someone gets sick with a cold or an infection, the mucus can become thickened and change color.

In this article, we take a look at the various colors that mucus or phlegm can be, and what these mean for a person’s health. We also examine different textures of phlegm and explain what a person can do if their phlegm changes.

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The color of phlegm can indicate if the respiratory system is healthy or not.

The color of phlegm can give a lot of information about the possibility of what is going on with the lungs and other organs of the respiratory system.


Clear mucus is normal. It consists of water, salts, antibodies and other immune system cells. After being produced in the respiratory tract, most of it goes down the back of the throat and is swallowed.


Brown phlegm may indicate possible bleeding, and if so, is likely to be caused by bleeding that happened a while ago. Bright red or pink phlegm means the bleeding has happened more recently.

Black mucus may indicate the presence of a fungal infection. Someone who has black phlegm should contact their doctor immediately, especially if they have a weakened immune system.


White mucus signals nasal congestion. When the nasal cavity is congested, the tissues are swollen and inflamed, which slows the passage of mucus through the respiratory tract. When this happens, the mucus becomes thicker and cloudy or white.


Yellow mucus suggests that immune cells are starting to work at the site of the infection or another type of inflammatory insult.

White blood cells are the cells of the immune system that are responsible for fighting germs. As they continue to fight the infection, they get picked up by the mucus, giving it a yellowish tinge.


Green phlegm indicates a widespread and robust immune response. The white blood cells, germs, and other cells and proteins produced during the immune response are what give the phlegm its green color.

While phlegm of this color can point to an infection, antibiotics are not always needed. Most infections that lead to green phlegm are viral and usually resolve without treatment within a few weeks.

Using antibiotics when they are not needed can be harmful, as bacteria can build up resistance. If green phlegm is accompanied by breathing difficulties, chest pain, or coughing up blood, visit a doctor urgently.


Red phlegm signals the presence of blood. There are many reasons for blood in the phlegm. Even just a lot of coughing, such as with a respiratory infection, can sometimes cause small blood vessels in the lungs or airways to break and bleed.

In other situations, blood in the mucus can indicate the presence of a serious medical condition.

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Coughing or sneezing helps the body get rid of foreign or harmful things. Healthy phlegm will usually have a watery texture.

Phlegm can also take on different textures, ranging from watery to thick and tacky. Thin and watery mucus is usually normal and indicates a healthy respiratory tract.

During an infection, immune cells, germs, and debris build up in the phlegm, making it thicker, stickier, and cloudier.

Coughing and sneezing help the body to clear out the excess mucus or phlegm and other things that do not belong in the respiratory tract.

Illness or infection are not the only things that can cause mucus to become thicker. Being dehydrated or even sleeping can cause the mucus to move slower and become thicker than usual.

Frothy sputum is mucus that is foamy and contains bubbles. Whitish-gray and frothy mucus can be a sign of chronic obstructive pulmonary disease (COPD) and should be mentioned to the doctor, especially if this is a new symptom.

Pink and frothy phlegm can mean that someone is experiencing severe left-sided heart failure, especially when combined with any of the following symptoms:

  • shortness of breath
  • sweating
  • chest pain

Anyone experiencing these symptoms should head to their local emergency room immediately.

It is important to realize that doctors cannot diagnose a particular disease or condition based on the color of a person’s phlegm.

Having green, yellow, or thickened phlegm does not always indicate the presence of an infection. Also, if an infection is present, the color of the phlegm does not determine whether a virus, a bacterium, or another pathogen has caused it. Simple allergies can also cause changes in the color of the mucus.

Antibiotics will not always resolve green mucus.

People who have white, yellow, or green mucus that is present for more than a few days, or experience other symptoms, such as fever, chills, a cough, or sinus pain, should visit their doctor. It is probably fine to wait a few days to try and treat the symptoms at home before making an appointment, however.

Someone who develops new or increased red, brown, black, or frothy sputum should call their doctor for an appointment immediately. These symptoms can be signs of a more serious medical condition that requires prompt treatment.

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Peppermint oil can be diluted and applied as a chest rub, which may ease coughs and aid relaxation.

Having white, yellow, or green phlegm can usually be treated at home.

People should try to get lots of rest and stay hydrated. Dehydration can worsen thick phlegm, making it harder to cough up.

Some people may find that gentle walking can help them cough up the excess phlegm.

Some other measures to try at home include using the following:


Running a humidifier can help to moisten the air, which eases breathing, making it easier to cough and loosen up the phlegm that is stuck in the chest.

Eucalyptus or peppermint oil

Eucalyptus or peppermint essential oils are the active ingredients found in many over-the-counter chest rubs.

When rubbed on the chest, these oils may aid relaxation, improve breathing, and make coughs more productive to get the phlegm out.

If using the essential oil directly, dilute it in a little coconut or almond oil before applying it to the chest. Undiluted oils can sometimes be a little intense or painful if applied directly to the skin.

Some people find that rubbing the oils into the soles of their feet and placing thick socks on can also be effective.

There is an excellent selection online with thousands of customer reviews if you want to buy eucalyptus or peppermint essential oils.


Over-the-counter expectorants, such as guaifenesin, help to thin the mucus, making it easier to cough up.

Expectorants are available for both children and adults and are available at the local pharmacy. It is important to read the directions and take the medicine exactly as instructed.

In most cases, home care measures are safe and effective ways to deal with abnormal phlegm.

It is important to call the doctor if the phlegm does not improve after a few days. An antibiotic may be needed to treat an underlying bacterial infection.

Anyone with pink, red, brown, black, or frothy mucus should contact their doctor or go to the local emergency room for an evaluation.