Coughing up blood, or hemoptysis, occurs when blood originates from the lower respiratory tract—including the trachea, bronchi, or lung parenchyma—and is expelled through a cough reflex. The blood is typically bright red, often frothy, and may be mixed with sputum.

Doctor Dang Thi Mai Khue, Deputy Head of the General Internal Medicine Department at Tam Anh General Hospital, Ho Chi Minh City, notes that many people confuse coughing up blood with vomiting blood due to stomach issues or bleeding from the nose or throat. Correctly identifying the source of bleeding is crucial for determining the cause and selecting appropriate treatment.

Pneumonia and bronchitis are common causes of hemoptysis, especially when the inflammation is severe or prolonged. Patients often experience fever, persistent coughing, phlegm production, chest pain, fatigue, and may notice streaks of bright red or light pink blood in their sputum.

When the respiratory tract is inflamed, the bronchial lining and underlying small capillaries become engorged, edematous, and more vulnerable to damage. Prolonged or violent coughing can rupture these capillaries, leading to small amounts of blood mixing with sputum and being expelled during a cough. In most cases, hemoptysis improves once the infection is controlled and inflammation subsides.

Bronchoscopy is one of many methods used to identify the cause of coughing up blood. Photo: Tam Anh General Hospital

Pulmonary tuberculosis remains a frequent cause of hemoptysis. Patients may also experience afternoon fevers, night sweats, weight loss, loss of appetite, fatigue, or chest pain.

Tuberculosis bacteria cause chronic inflammation and destroy lung tissue, forming cavities or necrotic areas. When these lesions extend to blood vessels, the vessel walls can erode, causing blood to leak into the airways. Depending on the extent of the damage, patients may only cough up a few specks of blood, but some cases involve large amounts of blood, which can be life-threatening if not treated promptly.

Bronchiectasis is a condition where the bronchi are permanently widened due to chronic inflammation or damage. Patients frequently experience persistent coughing with significant sputum production, recurrent respiratory infections, and may cough up blood multiple times.

Chronic inflammation destroys the bronchial walls and promotes the growth of new blood vessels around the damaged areas. These new vessels are often thin, fragile, and prone to rupture during forceful coughing or acute infection episodes. Blood then flows into the bronchial lumen, mixes with sputum, and is expelled when the patient coughs.

Coughing up blood is a significant warning sign of lung cancer, particularly in individuals over 40 with a history of smoking or prolonged exposure to smoke, dust, or chemicals. This symptom often accompanies persistent coughing, chest pain, hoarseness, weight loss, fatigue, or shortness of breath.

Doctor Khue explains that a growing tumor can invade the bronchial lining or erode into blood vessels within the lungs. Blood from damaged vessels then enters the airways and is expelled with sputum when the patient coughs. Recurrent hemoptysis, especially in individuals with risk factors, requires early examination to rule out lung cancer or other malignancies.

Pulmonary embolism occurs when a blood clot blocks a pulmonary artery, leading to acute ischemia in a portion of the lung tissue. Patients typically experience sudden shortness of breath, chest pain that worsens with deep breaths, rapid heartbeat, palpitations, and may cough up blood.

In the infarcted lung area due to lack of blood supply, capillaries can be damaged, leaking blood into the alveoli. This blood is then brought into the airways and expelled through the cough reflex. Pulmonary embolism is a medical emergency requiring urgent treatment due to the risk of respiratory failure and death.

Beyond respiratory conditions, certain cardiovascular diseases, such as mitral stenosis or heart failure, or autoimmune conditions causing vasculitis, can also lead to hemoptysis.

Doctor Khue states that in individuals with mitral stenosis or left heart failure, increased pressure in the pulmonary circulation makes lung capillaries more susceptible to rupture and bleeding. Meanwhile, autoimmune diseases like vasculitis can directly damage blood vessel walls in the lungs, leading to alveolar hemorrhage and manifesting as hemoptysis. Although less common, these are causes that doctors must carefully evaluate to avoid missing serious underlying conditions.

Doctor Khue advises that not all cases of coughing up blood indicate cancer, but even small amounts of blood should not be dismissed. A few streaks of blood mixed in sputum can be an early sign of many respiratory diseases that require timely detection and treatment.

To determine the cause, doctors may order chest X-rays, chest CT scans, bronchoscopy, sputum tests, or other specialized tests depending on the individual case. Patients should never self-medicate with hemostatic drugs, antibiotics, or cough suppressants without a diagnosis, as this can mask symptoms and delay the detection of the underlying condition.

Doctor Khue also recommends that individuals experiencing hemoptysis, especially if it recurs frequently, involves increasing amounts of blood, or is accompanied by persistent fever, shortness of breath, chest pain, weight loss, or fatigue, should seek medical attention. Early diagnosis and correct treatment help control symptoms and improve the chances of effective recovery.

Nhat Thanh