Coughing Up Blood – 7 Possible Causes

Coughing up blood: what does it mean, and when is it an emergency?

Coughing up blood immediately makes most people think of the worst possibility. Yet this symptom can have many causes, from simple bronchitis to lung cancer, and most are treatable. In medicine, hemoptysis refers to blood coming from the airways or lungs. In this article, we discuss how to tell whether the blood is really coming from the lungs, the most common causes, which situations are emergencies and what your doctor will do.

First, distinguish this: is the blood really coming from the lungs?

Not all blood coming from the mouth comes from the lungs. Blood may also come from the stomach, esophagus, nose, or mouth, and doctors call this pseudohemoptysis. For example, if your nose bled during the night or your gums are bleeding, you may see blood in your sputum in the morning. Rinsing your mouth first and checking your gums and nose may help identify the source.

The most common causes of coughing up blood

The distribution of causes varies greatly depending on where patients are assessed. Respiratory infections are the most common cause in outpatient settings such as primary care. In hospitalized patients, bronchiectasis, lung cancer, bronchitis, and pneumonia are prominent. In countries where tuberculosis is common, it is one of the most important causes.

1. Bleeding from the nose, mouth, and throat

If your nose bleeds while you are lying on your back asleep, blood may run down your throat and be coughed up in the morning. Gum disease can cause a similar picture. This is not true bleeding from the lungs. For a nosebleed, it is recommended to sit leaning forward and firmly pinch just above the nostrils for 10-15 minutes. Go to an emergency department if the bleeding does not stop in 10-15 minutes, is very heavy, follows a head injury, or is accompanied by weakness, dizziness, or difficulty breathing. We discuss when frequent nosebleeds may be a sign of cancer in this article.

2. Respiratory infections

Infections such as bronchitis, pneumonia, and laryngitis are the most common cause of coughing up blood, especially in outpatients. Severe coughing may damage small vessels in inflamed airways, causing streaks of blood in sputum. Fever, weakness, and sputum commonly accompany this. Viral bronchitis usually resolves on its own; bacterial infections and pneumonia may require antibiotic treatment. Severe pneumonia may require hospital treatment.

3. Bronchiectasis

Bronchiectasis is the permanent widening and structural damage of the airways. It usually develops after previous severe infections (such as childhood pneumonia, whooping cough, or tuberculosis). These patients have a persistent productive cough and recurrent infections. Bronchiectasis is among the most common causes of coughing up blood in cases assessed in hospital and is also an important cause of severe bleeding. Studies in Türkiye have reported coughing up blood in 2% to 60% of patients with bronchiectasis.

4. Chronic obstructive pulmonary disease (COPD)

COPD is a lung disease involving persistent and often progressive airflow obstruction that causes shortness of breath, cough, and sputum due to abnormalities in the airways (bronchitis, bronchiolitis) and/or air sacs (emphysema). Smoking is its most important cause. According to the World Health Organization, COPD is the third leading cause of death worldwide; it caused 3.4 million deaths in 2023. In a study in Adana, Türkiye, COPD was found in about 19% of adults over 40. Patients with COPD may have blood in their sputum during exacerbations. However, because most patients with COPD have smoked for a long time, coughing up blood must also be assessed for lung cancer.

5. Lung cancer

Coughing up blood is an important warning sign of lung cancer. About 10% of patients newly diagnosed with lung cancer cough up blood. In a UK study based on primary care records, respiratory tract cancer was subsequently detected in 7.5% of men and 4.3% of women presenting with coughing up blood; this proportion rose to 17% among men aged 75-84. In other words, the risk increases markedly with age and smoking.

The UK's National Institute for Health and Care Excellence (NICE) recommends that anyone aged 40 and over with unexplained coughing up of blood be referred for urgent assessment for suspected cancer. An important note: a normal chest X-ray does not rule out cancer; lung cancer can be detected in about 10% of patients who cough up blood despite a normal chest X-ray. People at risk therefore need computed tomography.

Other symptoms of lung cancer include a persistent cough or one that changes in character, shortness of breath, chest pain, hoarseness, unexplained weight loss, and fatigue. For details, see our lung cancer guide, and for symptoms that may differ in women, see this article. For smokers, another option for early detection before symptoms develop is screening with low-dose CT.

6. Tuberculosis (TB)

Tuberculosis is one of the most important causes of coughing up blood worldwide. In a study of hospitalized patients with tuberculosis, about one-third were found to cough up blood. A persistent cough, night sweats, fever, and weight loss are typical symptoms. Tuberculosis is transmitted through germs released into the air when people with the disease cough.

Treatment involves combining several antibiotics rather than using a single drug. The World Health Organization's standard treatment lasts 6 months: four drugs (isoniazid, rifampicin, pyrazinamide, and ethambutol) for the first 2 months, followed by two drugs (isoniazid and rifampicin) for 4 months. Shorter 4-month regimens can also be used in selected patients aged 12 and over. Completing treatment in full is essential both for recovery and to prevent drug resistance.

7. Pulmonary embolism

This is a clot formed in the leg veins blocking vessels in the lungs, and it requires emergency treatment. About 5–7% of patients with pulmonary embolism cough up blood; sudden shortness of breath and chest pain are more common symptoms. Recent surgery or trauma, a fracture, pregnancy and the postpartum period, active cancer, use of birth control pills, and immobility lasting more than 3 days are risk factors.

8. Blood-thinning medications

Coughing up blood may be a sign of bleeding in people taking warfarin or newer blood thinners. Seek medical attention immediately if you notice severe or recurrent bleeding while taking these drugs. Do not stop your medication on your own, but be sure to inform your doctor. Taking blood thinners does not mean there cannot also be another disease causing the bleeding; the cause still needs to be investigated. For general information about bleeding in different parts of the body, see our article on bleeding.

9. Heart diseases

Heart failure and narrowing of the mitral heart valve can increase pressure and cause fluid to build up in the lungs, leading to pink, frothy sputum or coughing up blood. These patients usually also experience shortness of breath, particularly when lying down, and swelling in the legs.

10. Rarer causes

• Pulmonary vascular abnormalities (arteriovenous malformations): Abnormal connections between blood vessels may cause bleeding if they rupture.
• Fungal infections: Aspergilloma, particularly when it develops in old tuberculosis cavities, can cause severe bleeding.
• Blood vessel inflammation (vasculitis): Diseases such as granulomatosis with polyangiitis, Goodpasture syndrome, and lupus.
• Other causes: A foreign body, lung abscess, cocaine use, and pulmonary endometriosis, which causes recurrent bleeding with menstruation in women.

Coughing up blood in people with cancer

Coughing up blood in a patient receiving cancer treatment must always be taken seriously. The lung tumor itself, a low platelet count, anticoagulant treatment, or some cancer drugs may cause bleeding. For example, bevacizumab is not used in patients with squamous cell lung cancer because it causes serious lung bleeding in these patients; it should also not be given to patients who have recently coughed up half a teaspoon or more of blood. If you are receiving cancer treatment and cough up blood, even a small amount, call your oncology team immediately. We explain in detail which symptoms during treatment require you to contact your team in this article.

When is it an emergency?

The vast majority of episodes of coughing up blood (more than 90%) involve small amounts and are not life-threatening. However, coughing up blood is a symptom that requires medical advice even if it happens only once. Some situations require emergency intervention:

Severe (massive) hemoptysis is defined as coughing up more than 200 milliliters of blood in 24 hours; however, the rate of bleeding and whether it obstructs the airway are now considered more important than the amount. The main danger in this situation is blood filling the airways and preventing breathing rather than blood loss itself. The first option for severe bleeding is to close the bleeding vessel through access via the groin or arm, a procedure called bronchial artery embolization; this can stop the bleeding in most patients. The most common causes of this type of bleeding are bronchiectasis, lung cancer, and tuberculosis.

What will the doctor do?

The doctor will first ask about the amount of blood, how long it has been happening, accompanying symptoms, your smoking history, and the medications you take. A stepwise assessment is then performed to identify the source and cause of the blood:

Computed tomography is more sensitive than bronchoscopy for identifying the site and cause of bleeding and is now the first-choice advanced investigation. We explain what it means if a lung nodule is found on CT in our article on lung nodules. Sputum tests are performed if tuberculosis is suspected, and blood tests if a bleeding tendency is suspected. Despite all investigations, no cause is found in a substantial proportion of patients; the course is usually favorable in these cases, but people at risk need continued follow-up.

What should you do in practice?

• Stay calm, but do not ignore it. Most episodes of coughing up blood are not serious, but the cause still needs to be investigated.
• Check the source. Rinse your mouth and check your gums and nose.
• Make a note. Record the amount of blood (a streak, a clot, or a spoonful), its color, when it started, and accompanying symptoms; take a photo if possible.
• Know your risk factors. Do not wait if you are over 40, smoke or used to smoke, take blood thinners, or are receiving cancer treatment.
• Recognize emergency symptoms. Call 112 immediately if there is a large amount of blood, shortness of breath, chest pain, or dizziness.
• Stop smoking. Many of the most serious causes of coughing up blood are related to smoking.

Frequently asked questions

I saw a streak of blood in my sputum once; should I be concerned?

A small amount of blood on a single occasion is often due to severe coughing or an infection. Still, consult your doctor; assessment is needed particularly if you are over 40, smoke, or the blood recurs.

Does coughing up blood always mean cancer?

No. The most common causes are infections, bronchiectasis, and COPD. However, lung cancer is an important possibility, and risk increases with age and smoking. The possibility of cancer must therefore be assessed with CT in people at risk.

My chest X-ray was normal; does that rule out cancer?

No. Lung cancer can be detected in about 10% of patients who cough up blood despite a normal chest X-ray. If you are at risk, you may need computed tomography.

No cause was found for my coughing up blood; what does this mean?

Despite all investigations, no clear cause is found in 20–50% of patients, and most of these people do not have another bleeding episode or have a favorable course. However, reassessment is needed if bleeding recurs or new symptoms appear.

I take blood thinners and saw blood in my sputum; what should I do?

Contact your doctor or an emergency department immediately without stopping the medication on your own. Severe or recurrent bleeding requires emergency assessment.

How can I distinguish coughing up blood from vomiting blood?

Blood from the lungs comes out with coughing and is bright red and frothy. Blood from the stomach comes with vomiting, is dark red or looks like coffee grounds, and may be accompanied by black stools. Medical attention is needed in both cases.

Glossary

Hemoptysis

Coughing up blood from the airways or lungs.

Pseudohemoptysis

Blood coming from somewhere other than the lungs (the nose, mouth, throat, or stomach) and appearing to be coughed up.

Hematemesis

Vomiting blood from the stomach or esophagus.

Bronchiectasis

Permanent widening and structural damage of the airways, involving persistent sputum production and recurrent infections.

COPD

Chronic obstructive pulmonary disease. A lung disease involving persistent and often progressive airflow obstruction, most commonly caused by smoking.

Bronchoscopy

Examination of the inside of the airways with a thin, flexible camera, with sampling if necessary.

Bronchial artery embolization

A procedure for severe lung bleeding in which a catheter is used to reach and block the bleeding vessel.