Blood in Phlegm: 7 Common Causes & What to Do

Updated on February 2023

In young and overall healthy patients, blood in phlegm is usually the result of prolonged or constant coughing, or of dried-up membranes in the respiratory airway. People who take anticoagulants may also notice some specks of blood in their sputum. 

However, blood in phlegm with other symptoms, like shortness of breath, fever, and green, yellow or frothy phlegm may be a sign of a more serious health condition, like a respiratory infection, bronchitis or pulmonary edema. 

If you notice  copious amounts of blood in your phlegm, if it lasts for over 3 days, or if you experience other symptoms, like difficulty breathing or wheezing, you should see a doctor or lung specialist for assessment possible treatment. 

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What causes blood in phlegm?

Bloody phlegm can occur for the following reasons: 

1. Persistent coughing

Allergies, the flu and persistent coughing can all cause blood in phlegm that is coughed up. This occurs due to irritation in the respiratory airways, which can become cracked and lead to some blood mixed with phlegm. These conditions are usually temporary and not serious, and the blood resolves within a few days, when the coughing improves. Read more about what can cause a persistent cough and how to treat it. 

What to do: You should try to soothe your coughing to avoid any further irritation. Some options include maintain hydration throughout the day, performing nasal irrigation to hydrate the mucous membranes, and taking a homemade cough syrup like propolis. Antihistamine medications, like loratadine, can also help.

You can also check-out these home remedies for coughs as a complement to your prescribed treatment.  

2. Anticoagulant medications

People who use anticoagulants, like warfarin or heparin, are at a higher risk for bleeding in various parts of the body. These medications make the blood thinner, which can put the patient at a higher risk for bleeding in various areas of the body. Anticoagulants can cause irritation to the respiratory tract, and a mild allergy, for example, can cause scant amounts of bleeding when coughing up phlegm.

What to do: Small amounts of blood in phlegm are not a significant finding, however large amounts of blood should. be assessed by a doctor.

3. Respiratory infections

Another relatively common cause of blood in phlegm is a lung infection, which can range from a mild cold or flu infection, to a more serious condition like pneumonia or tuberculosis. 

Respiratory infections are usually associated with other symptoms, like yellow or green phlegm, difficulty breathing, pale skin, blue lips or fingers, fever and chest pain. 

What to do: If you suspect a respiratory infection, you should see a doctor to confirm a diagnosis. After identifying the infectious agent, the doctor can initiate treatment, which may involve antibiotic use. See other ways you can get rid of phlegm using natural remedies as complement to medical treatment. 

4. Bronchiectasis 

Bronchiectasis is a chronic condition that is associated with permanent dilation of the bronchi. This can lead to excessive phlegm production, as well as frequent shortness of breath. The presence of blood in the phlegm is also a common finding. 

This condition does not have a cure, however treatment prescribed by a lung specialist can help relieve symptoms during flare-ups. 

What to do: Bronchiectasis should always be diagnosed by a doctor so that appropriate treatment can be prescribed. If you suspect you may have this condition, see a lung specialist for further examination with a chest x-ray and a thorough lung auscultation. 

5. Bronchitis

Bronchitis can also be associated with blood in phlegm. This condition is characterized by recurrent bronchial inflammation, which increases airway irritation and risk for bleeding. 

Phlegm from bronchitis is usually white or slightly yellow, although some strings of blood can also be noted. Other symptoms include wheezing, frequent fatigue and shortness of breath. 

What to do: Many times, rest and adequate hydration are sufficient for relieving bronchitis symptoms, However, if symptoms persist or if breathing worsens, you should seek medical assessment, as you may need IV medication. People who have chronic bronchitis are usually followed by a lung specialist, who will typically prescribe medication to manage symptom flare-ups. 

6. Pulmonary edema 

Pulmonary edema occurs when fluid accumulates inside the lungs. It is common in people with heart problems, like congestive heart failure, in which the blood is not adequately pumped to the rest of the body and starts to accumulate in small blood vessels in the lungs. 

In these cases, phlegm is often red or pink in color, and looks likely foamy. Other symptoms of pulmonary edema include difficulty breathing, blue lips or fingers, chest pain and increased heart rate. 

What to do: Pulmonary edema is considered a medical emergency. If you have a history of cardiac disease and suspect changes to your lung functioning, you should proceed immediately to the emergency room to confirm a diagnosis and start prompt treatment. Many times, hospital admission for treatment is advised. 

7. Lung cancer

Lung cancer is a more rare condition, but it can cause phlegm with blood. This type of cancer is most commonly seen in people over the age of 40 and in people who smoke. 

Other symptoms of lung cancer include persistent coughing that does not improve, weight loss, hoarseness, back pain and extreme fatigue. 

What to do: If you suspect cancer, especially if you have risk factors for cancer, you should see a lung specialist to complete thorough testing and confirm a diagnosis. Generally, the earlier cancer if caught, the better the rate of cure. 

When to see the doctor

You should consult your family doctor or a lung specialist if you persistently notice blood in phlegm. 

Urgent medical attention is advised if you experience any of the following: 

  • Blood in phlegm that does not improve after 3 days 
  • Large amounts of blood in the phlegm
  • Other symptoms, like high-grade fever, extreme difficulty breathing, pale skin, or blue fingers or lips

In the presence of these symptoms, the doctor may order testing like a chest x-ray, spirometry or a CT scan.