Mucus is a thin, slippery fluid that lines the nose, throat, and other passages to trap dust and germs. Phlegm is a thicker type of mucus produced in the lungs to catch and remove harmful particles and infections.
Mucus and phlegm are substances the body produces to help keep the airways and other sensitive areas moist, but they serve different roles.
People might produce too much mucus or phlegm due to infections, allergies, or irritants such as smoke. This excess may lead to symptoms, including a sore throat, frequent coughing, and congestion.
Phlegm is a type of mucus, but the two are different.
Phlegm
Phlegm, or sputum, is a thick, sticky mucus the respiratory system produces, typically in response to irritation or infection. Phlegm originates in the lungs and airways and varies in amount and color depending on the cause.
Mucus
Mucus is a slippery, watery substance produced primarily in the respiratory, digestive, and reproductive systems. Mucus acts as a lubricant to keep moist tissues such as the sinuses, mouth, and lungs from drying out.
Both mucus and phlegm serve a purpose.
Mucus is a natural defense system that helps trap dust, germs, and other particles, preventing them from reaching and harming deeper parts of the body. It lines the nose, throat, lungs, and intestines, protecting these areas and keeping them moist.
Mucus also plays a key role in helping the body eliminate irritants or harmful substances. Germs leave the body when a person coughs up mucus, blows it out through the nose, or swallows it, where it can break down safely in the stomach.
Similarly, phlegm traps and clears foreign particles such as dust, bacteria, and viruses from the airways. It is thicker than regular mucus and catches harmful substances in the lungs and respiratory tract.
Its sticky texture traps these particles, and tiny hair-like structures called cilia in the airways push the phlegm up and out of the body, often through coughing. This process helps to keep the lungs and airways clear and functioning correctly.
Learn more about mucus production and its purpose.
Yes, a person can have excess mucus. A person may not notice their body’s mucus production until they start making too much of it or the mucus changes color or consistency.
Is too much mucus or phlegm dangerous?
Excess mucus and phlegm can cause various effects that range from uncomfortable to potentially dangerous.
For example, producing too much mucus or phlegm may lead to:
- a runny nose and skin irritation
- blocked airways, making breathing difficult
- postnasal drip, which may lead to coughing and throat irritation
- increased risk of infection
- worsening of symptoms associated with existing lung conditions such as asthma
Furthermore, a
Learn about excess mucus in the throat.
Generally, people notice increased mucus and phlegm production when they have an upper respiratory infection (URI) or lower respiratory infection (LRI).
URIs are common, accounting for
- the common cold
- influenza (flu)
- sinus infections
- tonsillitis
- sore throat, such as group A Streptococcus
- laryngitis, or inflammation of the vocal cords
LRIs occur in the airways below the larynx and include:
Both URIs and LRIs are treatable and, depending on the infection, sometimes clear up on their own.
However, serious complications can occur with LRIs, so it is critical to follow a healthcare professional’s advice on recovery.
Causes of excess mucus not related to infection
Possible reasons for excess mucus or phlegm that are not due to sickness include:
- allergies
- dry air or irritants in the air
- certain foods such as dairy, gluten, and greasy or spicy foods
- dehydration
- cold temperatures
- deviated septum
Learn about coughing up phlegm without illness.
Typical amounts of mucus go mostly unnoticed.
Signs that someone is experiencing excess mucus and phlegm may include:
- a sore throat
- increased need to clear their throat
- frequent coughing
- congestion or feeling of fullness in the chest
- difficulty breathing or taking a deep breath
- visible thick, discolored mucus or phlegm
Learn more about a cough with mucus.
Phlegm shows up in various colors, and those colors can help healthcare professionals determine whether a sputum culture or other medical procedure is necessary.
| Color | Cause |
| Clear, white, or gray | This is typical, but excess amounts of sputum may indicate lung disease. |
| Dark yellow or green | This may signal a bacterial or viral infection, such as pneumonia, or an inherited condition, such as cystic fibrosis. |
| Brown or brown spots | This may be old blood from cystic fibrosis or other bacterial lung infections. It could indicate breathing in brown substances such as dust or toxins |
| Black | Black phlegm is common in people who smoke or have black lung disease |
| Pink | Pink phlegm may indicate pulmonary edema, a condition associated with heart failure |
| Red | Red phlegm may indicate an internal injury, lung cancer, or a life threatening pulmonary embolism. Coughing up red or bloody phlegm requires immediate medical attention |
Learn more about the colors of phlegm and what they mean.
Treatment for excess mucus and phlegm varies and may depend on the cause and symptoms. If the cause is a viral infection, such as the cold or flu, a person can treat their symptoms at home to help ease symptoms.
For example, a person may:
- Use a vaporizer or humidifier: Keeping the airways moist may help reduce mucus production and soothe nostrils.
- Apply a warm compress: Applying a warm compress on the face may help soothe sinus pressure.
- Flush the sinuses: Nasal irrigation helps to clear mucus and make breathing easier. There are various options, such as saline sprays and neti pots. A person can make their own saline solution if they choose.
Additionally, someone may consider over-the-counter medications such as expectorants to thin the mucus.
It is important to use these medications only for their intended purpose and to follow the instructions on the label carefully to avoid potential side effects or misuse.
Learn about some home remedies to clear phlegm and mucus.
Someone experiencing excess mucus or phlegm may consider seeking medical attention if:
- the mucus does not decrease with typical treatments, such as cold or allergy medications
- the mucus or phlegm continues to thicken
- the color changes
- they experience shortness of breath, wheezing, or chest pain
- they have a fever
- there is blood in the phlegm
How can a person tell the difference between mucus and phlegm?
Mucus is typically a thin, slippery fluid that goes mostly unnoticed unless production increases due to illnesses or allergies. Typically, a person does not need to cough up mucus, as they can clear it out when they blow their nose or use saline sprays or solutions.
Phlegm is a thicker, more viscous mucus in the lungs and airways. It is the type of mucus a person coughs up. Phlegm is often the body’s response to irritation or an infection and can range in color depending on the cause.
Should you spit or swallow excess mucus or phlegm?
Swallowing excess mucus or phlegm may cause discomfort. It is better to cough up and expel phlegm, especially when it is thick, or there is a lot of it.
Clearing mucus and phlegm helps remove irritants and bacteria from the airways.
Mucus and phlegm are substances that keep the airways moist, but they have different roles.
Mucus is a thin fluid that traps dust and germs, while phlegm is thicker and produced in the lungs to remove harmful particles.
Infections, allergies, and irritants, such as smoke, can cause excess mucus and phlegm production, leading to symptoms such as coughing and congestion, but these are typically easily treatable.