Phlegm Symptoms

Medically Reviewed By William C. Lloyd III, MD, FACS

What are the signs of phlegm problems?

Phlegm is a thick, slippery and sticky substance produced by the throat, bronchial passages, and lungs. Phlegm, also called sputum, contains mucus and sometimes other substances, such as dead cells, pus, or foreign particles, including dust. You may not notice that you produce much phlegm unless you cough due to a respiratory infection, such as pneumonia, or if you have certain other diseases or conditions in which the body produces abnormal amounts or types of phlegm, such as cystic fibrosis and asthma.

Phlegm may be described as abnormally thick or frothy, and clear, yellow or green in color. Phlegm can also contain visible amounts of blood or may be pink in color. In some cases, it may be difficult for you to clear your breathing passages by coughing due to extremely thick phlegm.

Abnormal phlegm symptoms can be caused by a large variety of mild to serious health problems, including infections, malignancy, inflammation, allergy, trauma, medications, and airway obstruction. For example, phlegm may be caused by exposure to smoke, consuming certain foods, such as dairy products, or taking certain medications.

In some cases, p hlegm symptoms can be a sign of a serious or life-threatening disease or condition, such as chronic obstructive pulmonary disease (COPD) or lung cancer. Seek prompt medical care if you are coughing up or producing large amounts of phlegm, or if your phlegm is unusual, persistent, recurrent, or causes you concern.

Seek immediate medical care (call 911) if you have difficulty breathing; chest pain; shortness of breath; swelling of the throat, mouth or face; or are coughing up bloody, pink and frothy phlegm.

What other symptoms might occur with phlegm symptoms?

Phlegm symptoms may accompany other symptoms, which vary depending on the underlying disease, disorder or condition. For example, you may have a fever and body aches if your phlegm symptoms are caused by an infection.

Symptoms of an infection that can occur with phlegm symptoms

Infectious diseases, such as the common cold, flu, strep throat, and sinusitis, can cause other symptoms that occur with phlegm symptoms including:

Allergy symptoms that can occur with phlegm symptoms

Allergies can cause other symptoms that occur with phlegm symptoms including:

Serious symptoms that might indicate a life-threatening condition

In some cases, phlegm symptoms may occur with other symptoms that might indicate a serious or life-threatening condition, such as acute pulmonary edema or a serious asthma attack, which should be evaluated immediately in an emergency setting. Seek immediate medical care (call 911) if you, or someone you are with, have any of the following symptoms:

  • Bluish coloration of the lips, nails, and possibly the skin (cyanosis)

  • Chest pain, tightness or pressure

  • Coughing up blood or pink, blood-tinged phlegm

  • Coughing up large amounts of frothy mucus or phlegm

  • Decrease in level of consciousness or change in alertness including confusion or disorientation

  • Difficulty speaking

  • Rapid heartbeat (tachycardia)

  • Respiratory or breathing problems including choking, gasping, shortness of breath, not breathing, stridor (high-pitched breathing), or wheezing

  • Severe pain upon swallowing, inability to swallow, or drooling

  • Sudden swelling of the tongue, lips, mouth or face, or hives on the face or neck

What causes phlegm symptoms?

Phlegm is generally associated with diseases, disorders and conditions of the respiratory system, including the nose, throat, windpipe (trachea), bronchial tubes, and lungs, but can also be caused by conditions of the upper digestive tract and the cardiovascular system, such as congestive heart failure.

Phlegm symptoms are commonly caused by bacterial or viral infections of the lungs and upper airways. Healthy lungs are covered with a thin layer of mucus. When threatened by infectious germs or damaging foreign substances, such as smoke or dust, the lungs produce additional mucus. The mucus may thicken and must be expelled from the lungs through coughing in order to keep the airways clear.

In addition, certain foods, particularly dairy products, or medications, such as those for blood pressure, can cause or increase phlegm symptoms. Because there are so many different causes, some of which are life threatening, it is important to contact your doctor or health care practitioner to discuss your symptoms and address your concerns.

Infectious causes of phlegm symptoms

Phlegm symptoms can be caused by various viral and bacterial infections including:

  • Acute bronchitis (inflammation of the bronchial tubes usually caused by a viral infection or sometimes a bacterial infection)

  • Common cold (viral infection)

  • Croup (laryngotracheitis, inflammation of the voice box and windpipe usually caused by a virus)

  • Epiglottitis (rare, life-threatening inflammation of the epiglottis, a flap of cartilage that covers the windpipe and protects it from inhalation of food). Epiglottitis is usually caused by a viral infection and mainly affects infants and children.

  • Influenza (flu)

  • Laryngitis (inflammation of the larynx caused by a viral infection)

  • Pharyngitis (inflammation of the throat usually caused by a viral infection and sometimes a bacterial infection)

  • Pneumonia (lung inflammation, usually caused by a viral or bacterial infection)

  • Sinusitis (inflammation of the sinuses usually due to a viral, bacterial or fungal infection)

  • Tonsillitis (inflammation of the tonsils often caused by an infection)

  • Tuberculosis (serious infection affecting the lungs and other organs)

Other causes of phlegm symptoms

Certain foods and medications as well as a variety of conditions and diseases can cause phlegm buildup. They include:

  • Acid reflux or gastroesophageal reflux disease (GERD; stomach contents leak back into the esophagus and irritate the tissues)

  • Airway irritation or obstruction

  • Asthma and allergies

  • Chronic obstructive pulmonary disease (COPD; a chronic lung disease including emphysema and chronic bronchitis)

  • Congestive heart failure (deterioration of the heart’s ability to pump blood)

  • Consuming dairy products

  • Cystic fibrosis (CF; an inherited disease causing thick, sticky mucus that clogs the lungs, impairs breathing, and enables bacteria to grow)

  • Lung cancer

  • Medications, including those for controlling blood pressure and some types of chemotherapy

  • Pregnancy

  • Pulmonary edema (abnormal fluid buildup in the lungs)

  • Pulmonary embolism (blood clot in the lungs)

  • Smoking

  • Tumor of the larynx (voice box), mouth, or nasopharynx
  • Tumor of the larynx (voice box)

Questions for diagnosing the cause of phlegm symptoms

To aid in diagnosing the cause of your phlegm symptoms, your doctor or licensed health care provider will ask you questions related to your symptoms. Giving complete answers to these questions will help your health care provider in diagnosing the cause of your symptoms. Questions may include:

  • What does your phlegm look like? Is it thick or thin? What color is it?

  • How long have you had the phlegm symptoms?

  • Are you breathing through your mouth (instead of your nose)?

  • Are your phlegm symptoms keeping you up at night?

  • Do you have a fever?

What are the potential complications of phlegm symptoms?

Phlegm symptoms can be caused by an infectious process that may be treated easily. However, some underlying causes of phlegm symptoms can lead to serious complications. It is important to contact your health care provider when you have unexplained phlegm symptoms or if your phlegm is persistent, recurrent, or causes you concern. Once the underlying cause is diagnosed, following the treatment plan you and your doctor design specifically for you can help lower your risk of potential complications including:

  • Chronic tonsillitis
  • Difficulty sleeping
  • Organ damage
  • Pulmonary edema
  • Repeated lung infections and damage
  • Respiratory arrest and cardiac arrest
  • Spread of cancer
Was this helpful?
  1. What Are the Signs and Symptoms of COPD? American Thoracic Society (ATS).
  2. Collins RD. Differential Diagnosis in Primary Care, 5th ed. Philadelphia: Lippincott, Williams & Williams, 2012.
Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Jan 16
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