What Causes Blood in Mucus, and How Do You Know If It’s an Emergency?

If you cough and see blood in your mucus (hemoptysis), it’s understandable if you feel alarmed. Many different lung conditions can lead to this, and some can be life-threatening. 

But even though it can feel and look scary to cough up blood, it’s usually not something to worry about. Let’s take a look at what causes blood in mucus and the signs that it may be something serious. 

1. Airway irritation from coughing

Having irritation in your airways from a severe or chronic cough is one of the most common reasons for blood in mucus. Coughing can irritate the walls of the airways in your lungs or throat. This can result in blood streaks in the mucus or bloody phlegm. 

2. Lung infection

A lung infection can lead to mild bleeding that causes blood in mucus. The lungs have many blood vessels that take oxygen and nutrients through your body. Sometimes, an infection can make these blood vessels rupture.

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

• Bronchitis

• Pneumonia

• Tuberculosis

When an infection is causing blood in mucus, people often have other symptoms as well, such as:

• Fever

• Chest pain

• Productive cough

3. Bronchiectasis and COPD

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

EXPERT PICKS: WHAT TO READ NEXT

• What’s your cough trying to tell you? Your cough’s sound or timing can hint at what’s causing your symptoms. Learn more about what your cough might say about your illness.

• Is your cough serious? Most coughs go away on their own. But sometimes they can signal a serious health condition, like pneumonia or heart problems. Learn when and why to get checked for a cough.

• Soothe your throat. Compare over-the-counter treatments for wet and dry coughs, plus learn how to ease a cough with common pantry staples.

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

In addition to bloody phlegm, symptoms of bronchiectasis may include:

• A daily, chronic cough

• Lots of brown mucus or phlegm

• Shortness of breath

• Chest pain

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

Read more like this

Explore these related articles, suggested for readers like you.

Can’t Stop Coughing? Here’s When to See Your Doctor

What Are Hiccups? What Causes Them and How to Make Them Go Away

What Does Bronchitis Feel Like?

What Does a Blood Clot Feel Like?

View more

4. Inflammation

Any condition that causes inflammation in your body and lungs can lead to bloody mucus. This can damage lung tissue and cause bloody phlegm. This is commonly seen when autoimmune conditions affecting your 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, too. These can include:

• Rash

• Hair loss

• Fatigue

• Achiness

• Swollen lymph nodes

5. Heart failure

Heart failure doesn’t just affect the health and function of your heart. It can also lead to changes in your lungs. Heart failure affects your heart’s ability to pump blood to the rest of your body. This can lead to congestion and pressure to build up in your lungs. This congestion can cause small breaks in the blood vessels in your lungs. That’s what can cause bloody mucus when you cough. 

Although heart failure can lead to a cough with bloody mucus, 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 your lungs. It often starts as a blood clot that has formed in your leg and traveled to your lungs. A PE can lead to bleeding in your lungs, which may lead to coughing or coughing up blood-streaked mucus. 

In the U.S., about 900,00 people are affected by PE each year. 

Sometimes, a pulmonary embolism causes no symptoms. But when symptoms do happen, they can include 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 your 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 your lungs can result from both lung cancer or the spread of other cancers to your lungs. This bleeding 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 your chest

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

8. Injury to the lungs or arteries

Serious injuries to the chest area can lead to bleeding in your lungs. These types of injuries include:

• Pulmonary contusion (a large bruise on your lung)

• Lung laceration (a cut in the lung tissue)

These types of injuries typically only happen after more severe trauma, like a high-speed car crash or a gunshot wound in the chest. More minor injuries — like a broken rib from a fall — usually don’t cause blood in mucus. 

9. Blood thinner medications

Anticoagulants (blood thinners) can increase the risk of bleeding in any part of your body. Blood thinners are more likely to cause bleeding from your nose or gastrointestinal tract. Bleeding in your lungs is less common. But it can happen, especially if someone who takes blood thinners has any of the above lung conditions. 

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. Sometimes, 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 conditions that can cause blood in mucus can be serious. So, it’s important not to ignore this symptom. 

But this doesn’t mean you should worry. If you’re otherwise healthy, there’s a good chance it’s nothing serious. 

The best way to find out is to talk to a healthcare professional. They can check things out with some simple tests, like a chest X-ray or blood work. Getting checked 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 but 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.

Some signs mean bloody mucus is an emergency. Pay attention to how the mucus looks, how much blood you’re coughing up, and 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 instead of urgent care. An ER has more testing and treatment available if needed. This is the fastest way to rule out serious conditions and get any treatment you might need.

How is hemoptysis (bloody mucus) treated?

The main way to treat hemoptysis is to treat the underlying cause. This means treatment for bloody mucus can vary a lot from person to person. 

In most cases, the bleeding itself doesn’t require any specific treatment. But people who take blood thinners may need to temporarily hold their medication until the bleeding stops.

If someone develops life-threatening bleeding in their lungs, treatment can involve:

• A breathing tube (also called intubation)

• A special procedure called embolization, which clots off the bleeding blood vessel

• Surgery, but only in severe cases

Why trust our experts?

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:

Katie E. Golden, MD

Katie E. Golden, MD, is a board-certified emergency medicine physician and a medical editor at GoodRx.

Our editorial standards

Meet our experts