Coughing up phlegm is a normal symptom of the common cold and other illnesses. However, producing excess mucus without being sick can be a sign of an underlying condition.

In this article, we discuss some causes of coughing up phlegm and how to treat them. We also explain what different colors of phlegm might indicate and when a person should see a doctor.

A person is coughing up phlegm but they are not sick.Share on Pinterest
Image credit: SDI Productions

A person may be coughing up phlegm for several reasons, including those below:

Acid reflux

Acid reflux, or gastroesophageal reflux disease (GERD), is where stomach acid moves up into the esophagus (food pipe). The main symptom of GERD is heartburn. It can also cause a cough.

Other symptoms include:

  • excess saliva
  • sore throat
  • difficulty swallowing
  • oral hygiene issues

Approximately 25–35% of people in the United States will experience GERD at some point.

Laryngopharyngeal reflux (LPR) is similar to GERD. In people with LPR, stomach acid moves up into the esophagus, the voice box, and, sometimes, the nasal cavity.

LPR occurs when the lower esophageal sphincter does not completely close. It can cause heartburn and other symptoms that include:

  • postnasal drip
  • frequent throat clearing
  • a cough
  • feeling a lump in the throat
  • excess mucus

Allergies

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

  • dry cough
  • sneezing
  • runny nose

Some people with allergies may also develop a postnasal drip, which occurs due to excess mucus production.

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.

Infections

A cough and excess mucus production are common symptoms of upper respiratory tract infections. Other symptoms of these infections include:

  • sore throat
  • runny nose
  • fever

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

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:

  • shortness of breath
  • wheezing
  • chest pain
  • coughing up blood

Heart failure

Heart failure is a condition in which the heart is unable to pump blood around the body properly. It causes symptoms that include:

  • difficulty breathing
  • fatigue
  • chronic cough
  • wheezing
  • production of white or pink phlegm
  • swelling of the ankles, legs, feet, and abdomen
  • nausea and poor appetite
  • disorientation and confusion
  • heart palpitations

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

The color of phlegm can indicate the cause of a cough and excess mucus production. However, it is not always consistent.

According to the American Lung Association, pneumonia can cause a cough that produces green, yellow, or bloody mucus.

A 2012 study examined the link between phlegm color and the presence of bacteria. The researchers found that green or yellow phlegm is more likely to contain bacteria than clear or white mucus.

However, few of the study participants had clear or white mucus for comparison.

Brown or black mucus is more common in people who smoke or have lung disease. For example, black phlegm is a sign of pneumoconiosis, which people sometimes refer to as “coal workers’ lung.”

Pink or rusty phlegm that contains blood can indicate the presence of a serious medical issue, such as heart failure.

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

Lung cancer is rare, and many of its symptoms are similar to those of other conditions, such as a lung infection. Some common lung cancer symptoms include:

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

A doctor may ask the individual about the duration of their symptoms and whether there are any triggers. They might also ask about the color or texture of the phlegm.

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

Blood tests or chest scans are sometimes necessary to rule out other underlying conditions.

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 that can relieve heartburn
  • surgery, in severe cases

Allergies

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

  • antihistamines
  • decongestants
  • nasal corticosteroids

Infections

Most upper respiratory infections will go away on their own. Over-the-counter decongestants and other products can help with some of the symptoms.

Infections that affect the lower respiratory tract may require treatment from a doctor.

Lung disease

A doctor might recommend the following treatments for COPD:

  • medication
  • pulmonary rehabilitation
  • supplemental oxygen
  • surgery

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

Heart failure

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

Long-term treatment options include:

  • lifestyle changes, such as exercising regularly and eating a healthful diet
  • medication, such as angiotensin converting enzyme (ACE) inhibitors
  • implantable devices, such as defibrillators
  • surgery, such as a coronary artery bypass or angioplasty

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

It is also important to see a doctor about a cough that produces blood.

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 usually 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, but while at-home remedies will be sufficient for some, others require long-term treatment.