It is not unusual to cough up phlegm with a common cold. However, it can also be a sign of a different, sometimes serious, underlying condition such as stomach acid reflux, lung disease, or heart disease.

This article discusses the possible causes of coughing up phlegm and how to treat them. It also explains what different colors of phlegm might indicate and when a person should contact a doctor.

Illustration of phlegm color cause: White may mean allergies or viruses, green may mean bacterial infection, red may mean lung injury or malignancy, and brown may indicate lung disease.Share on Pinterest
Illustration by Jason Hoffman.

Cough and excess mucus production are common symptoms of upper respiratory tract infections. These illnesses will typically also cause:

Lower respiratory tract infections, which include bronchitis and pneumonia, are more serious. They may produce longer-lasting symptoms.

Other possible causes of coughing up phlegm include:

Acid reflux

Acid reflux, also known as gastroesophageal reflux disease (GERD), is when stomach acid moves up into the esophagus (food pipe). GERD can occur due to dysfunction in the lower esophageal sphincter, a hiatal hernia, or dysfunction in the esophagus. The main symptom of GERD is heartburn, though acid reflux can also cause a cough.

Other symptoms include:

Approximately 18–28% of people in the United States will experience GERD at some point.

Laryngopharyngeal reflux (LPR) is similar to GERD. However, in people with LPR, stomach acid can move up into the esophagus, the voice box, and even the nasal cavity.

LPR can occur due to dysfunction in the lower esophageal sphincter, esophagus, and upper esophageal sphincter. This can cause heartburn and other symptoms, including:


Allergic rhinitis causes similar symptoms to a cold, such as:

Some people with allergies may also develop a postnasal drip, which occurs due to excess mucus production that leaks down the throat. This can cause a person to cough up phlegm.

Learn more about allergies here.

Environmental factors

Exposure to certain irritants, such as smoke and other fumes, can irritate the airway. This irritation can cause a cough with excess phlegm.

Learn more about air pollution and its effects on health here.

Lung disease

Some lung diseases, such as asthma and chronic obstructive pulmonary disease (COPD), cause a persistent cough and excess phlegm.

Other symptoms of lung disease include:

Heart failure

Heart failure is a condition in which the heart cannot correctly pump or relax to circulate blood around the body. It causes symptoms such as:

It is vital to report these symptoms to a doctor for immediate treatment.

The color of phlegm may help to indicate the cause of a cough and excess respiratory mucus production. Phlegm may be clear, cream, white, yellow, green, rust-colored, or red.

Lung diseases not related to infection, such as asthma or emphysema, tend to cause clear phlegm.

However, brown or black phlegm can also occur with lung disease, as well as with smoking. For example, black phlegm may be a sign of pneumoconiosis, which people sometimes refer to as “coal workers’ lung.”

Green phlegm is typically associated with infection. According to the American Lung Association, pneumonia can cause a cough that produces green, yellow, or bloody phlegm.

Pink or rust-colored phlegm that contains blood can indicate the presence of a serious medical issue such as tuberculosis or an abscess.

Learn more about phlegm colors here.

Lung cancer does not typically produce symptoms until it spreads. However, some people may experience early symptoms.

Lung cancer is a less common cause of coughing up phlegm without feeling ill, and many of its symptoms are similar to those of other conditions, such as a lung infection. However, bloody phlegm can be one of the symptoms. Additional common lung cancer symptoms include:

  • chronic cough
  • chest pain when laughing, breathing deeply, or coughing
  • hoarse voice
  • reduced appetite
  • trouble breathing
  • fatigue and weakness
  • chronic and recurring respiratory tract infections
  • wheezing

To diagnose the underlying condition causing a person to cough up phlegm, a doctor may ask them about the duration of their symptoms and whether there are any known triggers. They will likely ask about the color or texture of the phlegm.

The doctor will check for allergies or respiratory conditions, such as asthma. If they suspect that GERD is the cause, they may perform an upper GI endoscopy.

Blood tests or chest scans are sometimes necessary to rule out other conditions. A person may also need a sputum test to diagnose the type of lung disease.

Anyone with a persistent cough should contact a doctor for a diagnosis. In many cases, the cause will not be serious, though it might still require treatment.

If a person has a cough that produces blood, it is even more urgent that they contact a doctor, as the underlying cause could be serious.

The treatment for coughing up phlegm depends on its cause.

Acid reflux

Management strategies for GERD and LPR include:

  • lifestyle changes, such as stopping smoking and avoiding foods that trigger heartburn
  • medications, which might include antacids to help relieve heartburn
  • surgery, in severe cases


The primary treatment for allergies is to identify and avoid triggers. Other treatments include:


Most upper respiratory infections will go away on their own.

Over-the-counter decongestants and other products can help with some symptoms in the meantime.

Infections that affect the lower respiratory tract may require treatment from a doctor, who will most likely prescribe an antibiotic.

It is important that a person finishes the entire course of antibiotics, even if their cough and phlegm go away sooner.

Lung disease

A doctor might recommend the following treatments for COPD:

In most cases of asthma, people can effectively manage their symptoms with medication, such as quick-relief and corticosteroid inhalers.

Heart failure

Heart failure is a serious condition that requires immediate medical treatment.

Long-term treatment options include:

What is the difference between phlegm, mucus, and sputum?

Although people often use all three terms interchangeably, there is a slight difference between them. Mucus is a general term referring to the substance produced by mucous membranes anywhere in the body. Phlegm and sputum both refer to mucus produced in the lungs and lower respiratory tract.

Does COVID-19 cause coughing up phlegm?

Research shows that when a person first contracts COVID-19, it typically causes a dry cough. As the disease progresses, it may lead to phlegm production in severe cases.

What are some natural remedies for coughing up phlegm?

Treating coughing up phlegm depends on the underlying cause and may require contacting a doctor. However, a person may get some relief by gargling salt water. To do this, a person can dissolve ¼ teaspoon of salt in 1 cup of warm water and then gargle for 15–30 seconds.

Learn more about gargling with salt water here.

Most causes of coughing up phlegm are not serious. However, more severe conditions, such as COPD or heart failure, require lifelong treatment.

Coughing up phlegm is typically not a cause for concern. For example, GERD and the common cold are responsible for many cases of coughing up phlegm. However, in some cases, this symptom might indicate an undiagnosed condition.

Most causes are treatable. However, while at-home remedies will be sufficient for some, others will require long-term treatment.