Causes of Blood in Mucus, and How to Know If It’s an Emergency

If you cough and see blood in your mucus (hemoptysis), it’s understandable to feel alarmed. Many different conditions in the lungs can lead to this, and there are some life-threatening causes. But even though it can feel and look scary to be coughing up blood, most of the time bloody mucus isn’t something to worry about. 

There are many reasons why someone might cough up blood. These range from mild to life-threatening. Let’s take a look at what causes blood in mucus and the signs that it may be more serious. This way you’ll know when and where to get medical care.

1. Airway irritation from coughing

Having airway irritation from a severe or chronic cough is one of the most common causes of having blood in mucus. Coughing can irritate the walls of the airways in the lungs or the throat. And this can result in blood streaks in mucus or bloody phlegm. 

It’s important to seek care if you’re coughing up blood. Your medical team will need to figure out the cause of your cough and give you guidance on the best treatment options.

2. Lung infection

A lung infection can cause you to have blood in your mucus from mild bleeding. The lungs have many blood vessels that take oxygen and nutrients throughout the body. Infections can sometimes cause these blood vessels to rupture.

The most common lung infections that are likely to cause blood-tinged mucus are:

• Bronchitis

• Pneumonia

• Tuberculosis

The medical history and symptoms can sometimes give a clue that there may be an infection in the lungs. Many people with infections as the source of their bloody mucus will have other symptoms as well, such as:

• Fever

• Chest pain

• Productive cough

3. Bronchiectasis

Bronchiectasis is a condition where infections or inflammation damage the small airways of the lungs over time. These damaged airways have a hard time clearing mucus, and it can build up. This can lead to chronic cough and frequent infections. 

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Bronchiectasis is common in people who have chronic lung conditions like cystic fibrosis or chronic obstructive pulmonary disease (COPD).

In addition to bloody phlegm, symptoms of bronchiectasis include:

• Daily, chronic cough

• Lots of brown mucus or phlegm

• Shortness of breath

• Chest pain

• Nail clubbing (nail changes leading to thick and curved nails)

4. Inflammation

Any condition that causes inflammation in the body and lungs can lead to bloody mucus. Damage to the lung tissue as a result can cause you to have bloody phlegm. This is commonly seen with autoimmune conditions affecting the lungs, such as:

• Lupus

• Vasculitis

• Wegener’s granulomatosis

• Sarcoidosis

• Rheumatoid arthritis

If an autoimmune condition is the reason for bloody mucus, there are often other symptoms present. These can include:

• Rash

• Hair loss

• Fatigue

• Achiness

• Swollen lymph nodes

5. Heart failure

Heart failure can not only affect the health and function of the heart, but it can also lead to changes in the lungs. When the heart muscle isn’t strong, it’s no longer able to pump blood throughout the body well. This can lead to congestion in the lungs and a pressure buildup in the lungs. This congestion can cause small breaks in the blood vessels in the lungs — causing you to cough up blood. 

Although you can have a cough with bloody mucus with heart failure, it tends to have some other more common symptoms. Classic symptoms of heart failure are:

• Shortness of breath (can be worse when lying down)

• Weight gain

• Body swelling (mostly in the legs, feet, and abdomen)

• Fatigue

• Lightheadedness

6. Pulmonary embolism

A pulmonary embolism (PE) is a blood clot in the lung. It’s often the result of a blood clot that has formed in the leg and traveled to the lung. This can lead to bleeding in the lung and blood-streaked mucus. In the U.S., about 900,00 people are affected by PE each year. 

Sometimes there are no symptoms of a pulmonary embolism. But it can lead to a cough, with bloody phlegm. Other symptoms of a pulmonary embolism can be: 

• Chest pain

• Shortness of breath

• Heart palpitations

• Dizziness or lightheadedness

• Pain or swelling in the legs

A PE is a serious condition that can also be deadly in up to 30% of people. If you have symptoms of a PE, make sure you get medical attention right away. 

7. Cancer

Bleeding in the lung can result from both lung cancer or the spread of other cancers to the lungs. And this can cause brown mucus or bloody phlegm.

It’s not clear why lung cancer develops, but there are some risk factors that can make it more likely. These include:

• Smoking

• Chemical exposure

• Secondhand smoke exposure

• Family history of lung cancer

• History of radiation to the chest

People who have smoked are up to 30 times more likely to develop lung cancer than those who have never smoked. If you’re coughing up blood and have a history of smoking, talk with your primary care provider right away.

Can blood in mucus come from the throat or nose?

Sometimes, bloody mucus comes from bleeding in the upper part of the airway — like the nose or throat. These areas are filled with tiny blood vessels that can easily be irritated by inflammation or an infection. 

So, if you’re coughing up blood or brown mucus, it might also be from:

• Throat infection (pharyngitis)

• Tonsillitis

• Nasal congestion

• Nosebleeds

It can be hard to tell if blood is coming from the respiratory tract or upper gastrointestinal tract. So bloody mucus could also be coming from bleeding in the stomach or esophagus.

Should you see a healthcare professional for bloody mucus?

If you have repeated episodes of bloody mucus, it’s a good idea to get medical care. Some of the conditions that can cause blood in mucus are serious. So don’t ignore this symptom. 

But this doesn’t mean you should worry. There’s a good chance that it’s not something serious, especially if you’re otherwise healthy. 

The best way to know for sure is to talk with a healthcare professional. They can check things out with some simple tests, like a chest X-ray or blood work. This is especially important if you have a history of: 

• Heart problems

• Autoimmune disease

• Lung conditions

• Cancer

• Heavy smoking

Is coughing up blood an emergency?

If you have small streaks of blood in your mucus and feel well otherwise, you can get checked out at a primary care provider’s office. For anything more than small streaks of blood, it’s a good idea to get checked out sooner rather than later.

There are some signs that mean bloody mucus is an emergency. Pay attention to what the bloody mucus looks like, and try to estimate how much blood you’re coughing up. Also pay attention to any other symptoms you’re having. 

Go to an ER (emergency room) if you’re experiencing any of the following:

• Episodes of coughing that produce more than 1 tsp of blood

• Chest pain

• Shortness of breath

• Abnormally pale skin

• Dizziness when standing

• Complete loss of appetite or unexplained weight loss

• Fever

• Severe weakness or fatigue

It’s best to go to an ER rather than an urgent care. An ER has more testing and treatment available if needed. So this is the fastest way to rule out serious conditions and get any treatment you might need.

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Written by:

Michael Dreis, MD

Dr. Dreis is an emergency medicine physician currently practicing in Milwaukee, Wisconsin. He went to medical school at the University of Wisconsin – Madison and completed his residency at Henry Ford Hospital in Detroit, Michigan.

Edited by:

Karla Robinson, MD

Karla Robinson, MD, is a medical editor for GoodRx. She is a licensed, board-certified family physician with almost 20 years of experience in health through varied clinical, administrative, and educational roles.

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