There are many reasons for coughing up blood, including medical conditions, injuries and medications. It usually isn’t serious, and it will often go away on its own. But coughing up a lot of blood can be dangerous and a sign that you need emergency medical care.

Read on to learn about when to see a doctor, possible causes and other symptoms to watch for. To skip ahead to a specific cause, click on one of the links below:

If you’re coughing blood, it can mean there’s a problem in your airway

There are many different reasons why you may be coughing up blood from your lower airway, including infections, medications, medical conditions and injuries. When you cough blood from your lower respiratory tract, it can look pink, red or rust colored. It usually looks bubbly or frothy since the blood mixes with air and mucus on the way out.

When is coughing up blood serious? When to see a doctor about your symptoms.

If you’re coughing up any amount of blood, it’s a good idea to talk to a doctor. But it can be an emergency situation depending on the amount of blood and other symptoms you may have.

It’s also important to know that coughing up blood is not the same as vomiting blood. It’s always a medical emergency if you’re vomiting blood. (To learn more, skip ahead to the section on coughing blood vs. vomiting blood.)

The more blood that comes up, the sooner you should see a doctor

Most of the time, blood that you cough up comes from the lower respiratory tract – the space with your voice box, windpipe and bronchi (the main airways in the lung). The medical term for coughing up blood from the lower respiratory tract is hemoptysis.

Doctors classify hemoptysis into three types based on how much blood you cough up at once or over 24 hours. Here’s what to do based on the amount of blood you’re coughing up:

Get emergency care if you have any of these symptoms

If you’re coughing up blood, it’s likely that you’ll have other symptoms. No matter the type of hemoptysis you have, you should get emergency care if you have:

• Chest pain, shortness of breath or dizziness
• Blood in your stool or urine
• Signs of shock such as a rapid heartbeat or pale, clammy skin

Conditions that cause hemoptysis and why it happens

Hemoptysis can be caused by various conditions that affect your lower airway. These conditions can cause tissue inflammation and irritation, leading to bleeding and other symptoms.

Infections: The most common causes of coughing blood up

Many infections can affect your lungs and airways, and some can cause you to cough up blood or have red-colored mucus. But keep in mind that common viral infections, like colds and the flu, are unlikely to cause hemoptysis because the symptoms are less severe and don’t last as long.

If hemoptysis is caused by an infection, other common symptoms are a cough, fever, chills, shortness of breath, chest pain, weakness, fatigue and a sore throat.

Many lung infections can cause hemoptysis, but here are some of the more common ones:

• Bronchitis – Bronchitis is inflammation or swelling in the bronchial tubes. The main symptom of bronchitis is a cough, which can make hemoptysis more likely.
• Fungal infections – Fungal lung infections are rare but can cause hemoptysis and become serious without treatment. They are more common in people who are immunocompromised or have another lung condition.
• Lung abscess – An abscess is a pocket of pus that forms when your body tries to fight off an infection. As the lump gets bigger, it can damage the surrounding tissues and cause bleeding.
• Pneumonia – Different types of pneumonia cause inflammation in the air sacs of one or both of your lungs. Hemoptysis is more likely if you have a severe infection.
• Tuberculosis – Tuberculosis (TB) is a rare infection that damages lung tissue and blood vessels. Hemoptysis is a common symptom of TB and, in some cases, the amount that comes up can be life threatening (massive hemoptysis).

Medicines and supplements: Some can increase your chance of coughing up blood

Some medications and supplements increase the risk of bleeding or can directly irritate lung tissues. If you recently started taking a new medication or supplement, it may be the cause of hemoptysis, but you’ll want to talk to your doctor to make sure.

Medications that can cause hemoptysis include blood thinners, antiplatelet drugs and nonsteroidal anti-inflammatory drugs (aspirin, ibuprofen and naproxen). Don’t stop taking prescribed medicine before you clear it with your doctor.

Herbal supplements such as garlic, ginkgo biloba and ginseng can increase the risk of hemoptysis, especially in people with bleeding disorders. Always talk to your doctor before taking supplements, as some may not be safe for you.

Chronic lung diseases: Coughing up blood is a common symptom

Hemoptysis can be a common symptom of chronic lung disease because these conditions can cause long-term inflammation and tissue damage in the airways and lungs. These conditions may also include structural changes, such as scarring and airway widening, that make bleeding more likely when lungs are inflamed or under pressure.

Other symptoms of chronic lung disease include a cough that doesn’t go away, wheezing and shortness of breath. These symptoms are common with other conditions, including lung infections. The best way to find out if hemoptysis is caused by a chronic lung disease is to talk to your primary care doctor.

• Bronchiectasis – With this condition, the airways become abnormally widened and inflamed, making them prone to infection and bleeding.
• Chronic obstructive pulmonary disease (COPD) – COPD causes persistent inflammation and mucus buildup, which can damage airway linings and blood vessels, causing bleeding in the airway.
• Pulmonary arteriovenous malformations (AVMs) – AVMs are unusual connections between blood vessels in the lungs. Normally, blood flows through capillaries (the smallest blood vessels) where it picks up oxygen. In AVMs, blood skips this step and flows directly from arteries to veins. These abnormal connections are often weak and can break more easily, which may lead to coughing up blood.

Injuries and foreign materials: Coughing up blood can be a sign of tissue damage

Injuries can cause hemoptysis if they damage the structures or blood vessels within the lungs or airways. If you start coughing up blood following an injury, see a doctor right away.

• Trauma – There are several ways injuries can lead to bleeding in the respiratory system. A strong impact to the chest (blunt force trauma) can compress lung tissue enough to rupture blood vessels, causing internal bleeding. In other cases, bleeding results from penetrating trauma, such as when a broken rib or breastbone punctures the lung tissue. This kind of damage can tear blood vessels within the lungs, leading to bleeding into the airways or surrounding areas.
• Foreign substances – Breathing in hot air or chemicals or swallowing small objects can damage your airways and cause bleeding.
• Medical procedures – Sometimes medical tools used to help you breathe or look inside your lungs can accidentally hurt the airways, especially if your blood vessels are weak.

Cardiovascular conditions: Coughing up blood can mean you need emergency care

Coughing up blood is not a usual symptom of cardiovascular conditions, and it can mean that a heart or vascular condition is getting worse. Hemoptysis can be caused by increased pressure in the circulatory system related to blood clots and heart valve problems.

If your hemoptysis is caused by a cardiovascular condition, you may need emergency care. Be on the lookout for severe symptoms such as chest pain, skin that starts to look blue and shortness of breath. If you have a cardiovascular condition but don’t have severe symptoms, you should still follow up with your cardiologist, pulmonologist or primary care doctor as soon as you can.

• Pulmonary embolism (blood clot in the lungs) – This is when a clot travels to the lungs and becomes lodged in a pulmonary artery, blocking blood flow to parts of the lung tissue. When pressure builds up around the clot, it can damage the surrounding tissue and cause bleeding. Pulmonary embolisms are usually emergency situations.
• Heart failure – With heart failure, the heart doesn’t pump blood as well as it should. Because of this, blood can collect in the lungs. This causes pressure to build up in the tiny blood vessels in the lungs. If the pressure gets too high, the blood vessels can leak or burst, leading to hemoptysis.

Autoimmune and inflammatory conditions: Rare causes of coughing up blood

Some conditions, including autoimmune disorders, cause ongoing inflammation that can damage the blood vessels in the lungs and lead to bleeding into the alveoli (the tiny balloon-like air sacs in your lungs that exchange carbon dioxide for oxygen). If blood vessels or alveoli become damaged, you may cough up blood.

If the hemoptysis is caused by an autoimmune or inflammatory condition, you may or may not have a cough. However, you're likely to experience symptoms that affect other parts of your body.

Substance misuse: Can cause you to suddenly cough up blood

Crack cocaine and cocaine laced with levamisole will damage your lungs. It irritates and inflames the airways, making it more likely for blood vessels to burst. If hemoptysis is caused by substance use, it may start suddenly and without warning, especially in users with repeated exposure or underlying lung disease. Substance misuse can cause serious health problems. Talk to your primary care doctor about how to get help.

Cancer and abnormal cell growth: Rarely, coughing up blood is an early sign of cancer

Coughing up blood or bloody mucus can be a sign there’s a tumor or growth in your airways or lungs. Tumors or growths in the airway, throat and lungs may not cause noticeable symptoms if they’re small. But as they grow, they may press against surrounding tissues or damage nearby blood vessels, leading to bleeding. And if you have a lump in your neck that blocks the airway, you may also be more likely to develop respiratory infections like pneumonia or bronchitis.

Signs that the blood that came up isn’t from your lower airway

Here are some differences to keep in mind:

Coughing up blood vs. vomiting blood

Vomiting blood isn’t the same as coughing up blood. Vomiting blood is called hematemesis, and it’s always a medical emergency. Call 911 or go to the emergency room immediately, especially if you vomited a lot of blood.

Vomiting blood is caused by bleeding in the upper gastrointestinal tract, which includes the stomach and the esophagus (the tube that connects your mouth to your stomach).

Vomited blood is usually dark brown and clumpy, like coffee grounds. But it can also be bright red and liquid. Bright red blood is a sign of active bleeding, usually in the esophagus or stomach.

Vomiting blood can be a symptom of stomach ulcers, inflammation in your digestive system (gastritis) or swollen veins in the lower part of the esophagus (esophageal varices). Very rarely, it’s a symptom of esophageal cancer.

If you vomit blood, you may have other symptoms related to your stomach or digestion system, including stomach pain, bloating, nausea, loss of appetite or black stool color.

Coughing up blood or other red material that’s not frothy

If you cough up something that looks like blood, but it’s not frothy, it may be blood from the upper airway (mouth, nose, throat). Causes may include bleeding gums, nosebleeds, an injury to the mouth or a bacterial infection. It may also be a non-blood substance such as red dyes in food and beverages.

If the upper airway or mouth is the reason for coughing up blood (or red material), you are unlikely to have respiratory symptoms like wheezing or shortness of breath. It’s a good idea to talk to a doctor to make sure of the cause.

See a doctor if you’re coughing up or vomiting blood

If you’re coughing or vomiting blood, it’s important to see a doctor. And the more blood that comes up, the sooner you need help.

If you’re vomiting blood or coughing up a lot of blood, call 911 or go to the emergency room. If there’s not a lot of blood, make a primary care appointment. Your doctor will be able to diagnose the problem and connect you with the care you need.