COVID-19 can cause you to cough up blood, a symptom doctors call hemoptysis. It is uncommon compared to the hallmark symptoms of fever and dry cough, but it is well documented in the medical literature and can range from faint streaks of blood in sputum to rare episodes of massive bleeding. The reasons trace back to the virus’s tendency to damage the delicate lining of the lungs and the blood vessels running through them, and the picture gets more complicated when blood thinners, secondary infections, or pre-existing lung conditions enter the mix.
Why COVID Damages Lung Tissue Enough to Cause Bleeding
The lining of your lungs is a thin, fragile barrier. On one side sit tiny air sacs called alveoli; on the other, an equally thin layer of blood vessel wall. Gas exchange happens across this membrane with every breath. SARS-CoV-2 targets both sides. Studies of fatal COVID cases show what pathologists describe as progressive diffuse alveolar damage paired with excessive clotting and eventual remodeling of lung tissue and blood vessels. The virus injures the cells that produce surfactant (the substance that keeps air sacs from collapsing), damages the endothelial cells lining pulmonary blood vessels, and disrupts the body’s normal tissue-repair processes.1PubMed Central. Lung epithelial and endothelial damage, loss of tissue repair, inhibition of fibrinolysis, and cellular senescence in fatal COVID-19
When the alveolar-capillary barrier breaks down, blood can leak into the air spaces. Sometimes that blood stays trapped deep in the lungs and shows up only on imaging. Other times it works its way up and you cough it out. The extent of bleeding depends on how much damage has occurred and how many blood vessels are involved. In mild cases it might be a pinkish tinge in your phlegm. In severe cases, especially when a clot blocks a pulmonary artery and the tissue downstream dies (pulmonary infarction), the bleeding can be substantial.
How Common Is Hemoptysis in COVID Patients
Among the broad spectrum of COVID symptoms, hemoptysis sits firmly at the uncommon end. Large observational studies from 2020 and 2021 consistently placed it alongside diarrhea, headache, and sore throat as a rarer presentation compared to fever, cough, and fatigue.2PubMed Central. Case Series of COVID-19 Presenting with Massive Hemoptysis Estimates of prevalence varied by study and setting, but most put the figure in the low single digits as a percentage of hospitalized COVID patients.
That said, rarity does not mean insignificance. When hemoptysis does appear in a COVID patient, clinicians pay close attention because it can signal complications like pulmonary embolism, alveolar hemorrhage, or a secondary fungal infection in the lungs. It also sometimes arrives before any of the more typical COVID symptoms, which created diagnostic surprises early in the pandemic.
When Coughing Up Blood Is the Very First Symptom
One of the more striking findings published during the pandemic was that some patients showed up at emergency departments coughing up large amounts of blood and had no other complaints: no fever, no shortness of breath, no body aches. Only after testing did they turn out to be positive for SARS-CoV-2. A case series from Turkey documented three such patients who arrived with massive hemoptysis as their sole presenting symptom. At the time of publication, the authors noted that massive hemoptysis as a first sign of COVID had not been previously reported.2PubMed Central. Case Series of COVID-19 Presenting with Massive Hemoptysis
A separate case report described a patient whose first sign of illness was hemoptysis, and imaging revealed bleeding concentrated in the left lung. CT angiography confirmed alveolar hemorrhage, and bronchoscopy pinpointed the source to the left upper lobe. The bleeding vessel was ultimately sealed using a procedure called bronchial artery embolization.3PubMed Central. Haemoptysis as the first presentation of COVID-19: a case report These cases mattered beyond their novelty because they highlighted a diagnostic blind spot: if a clinician did not think to test for COVID in a patient with unexplained lung bleeding, the infection could be missed entirely, with consequences for both the patient and the people around them.
The Role of Blood Clots
COVID-19 earned a reputation early on for causing abnormal clotting. Patients in intensive care frequently developed clots in the legs, lungs, and sometimes smaller vessels throughout the body. The virus provokes an intense inflammatory response in blood vessel walls, and that inflammation tips the balance toward clot formation. When a clot lodges in a pulmonary artery, the downstream lung tissue can become starved of blood, die, and bleed. This is one of the main pathways by which COVID leads to hemoptysis, especially the more severe variety.
Anticoagulant therapy, which became a standard part of COVID management for hospitalized patients, adds a layer of complexity. Blood thinners reduce the risk of dangerous clots but simultaneously make any existing area of vascular damage more prone to bleeding. Clinicians managing COVID patients who developed hemoptysis often faced a difficult balancing act: the very medication protecting against life-threatening clots in the lungs could be worsening the bleeding from damaged tissue. Adjusting doses and closely monitoring these patients became a recurring challenge in critical care settings.
Secondary Infections That Worsen Bleeding
Severely ill COVID patients, particularly those on ventilators or receiving steroids and other immune-modifying drugs, became vulnerable to secondary infections. One that caught particular attention was invasive pulmonary aspergillosis, a fungal infection that invades lung tissue and blood vessels. Aspergillus species thrive in damaged lung environments, and COVID-ravaged lungs provided a near-ideal foothold. When this fungus grows into blood vessel walls, it can cause sudden and severe hemoptysis.
Diagnosing aspergillosis in a COVID patient is tricky. The gold standard involves bronchoscopy with tissue samples and fluid cultures, but bronchoscopy generates aerosols that put healthcare workers at high risk of infection. During the pandemic, it was considered relatively contraindicated in patients with suspected or confirmed COVID.4PubMed Central. Spontaneous Hemoptysis in a Patient With COVID-19 Clinicians often had to rely on blood markers and imaging patterns to make a presumptive diagnosis and begin antifungal treatment without the confirmatory bronchoscopy they would normally have performed.
Nosebleeds Mistaken for Hemoptysis
Not every instance of blood appearing in the mouth or sputum during COVID originates in the lungs. Nosebleeds can produce blood that drains down the back of the throat and gets coughed up, creating what looks like hemoptysis but technically is not. This is sometimes called pseudohemoptysis, and it matters because the treatment and urgency are quite different from true lung bleeding.
A prospective study examined whether nosebleeds were more common in COVID-positive patients. Among patients presenting to hospital with nosebleeds, about 15 percent tested positive for SARS-CoV-2, compared to roughly 2.5 percent in a control group, a statistically significant difference.5PubMed Central. Epistaxis as a marker for severe acute respiratory syndrome coronavirus-2 status – a prospective study The virus can inflame the nasal mucosa, and frequent forceful coughing or nose blowing adds mechanical stress. If you are COVID-positive and see blood when you cough, it is worth considering whether the source might be your nose rather than your lungs. A few clues help distinguish the two: blood mixed thoroughly into sputum and accompanied by a cough that feels deep in the chest points toward a pulmonary source, while blood that drips from the nose or appears mostly in the back of the throat when you tilt your head forward suggests a nasal origin.
Tracheostomy Patients Face Higher Risk
People who breathe through a tracheostomy (a surgically created opening in the windpipe) already have a higher baseline risk of airway bleeding because the normal defense systems of the upper airway are bypassed. When SARS-CoV-2 infection is layered on top, the risk increases further. The virus reduces mucous production in the trachea and makes secretions thicker, which promotes the formation of dried crusts inside the airway. Those crusts irritate and damage the tracheal lining, trigger severe coughing, and aggravate bleeding.6PubMed Central. SARS-CoV-2 infection increases airway bleeding risk in patients after tracheostomies
This interaction mattered most in long-term care facilities and for patients who had tracheostomies placed during prolonged ICU stays for COVID itself. Vigilant suctioning, humidification of inspired air, and close monitoring for signs of infection were the practical countermeasures. For caregivers looking after someone with a tracheostomy during a COVID infection, any new or worsening blood in tracheal secretions warranted prompt medical evaluation.
When to Seek Emergency Care
A small streak of blood in your phlegm while you are coughing hard from any respiratory illness, COVID included, is not automatically an emergency. Intense coughing can irritate the throat and upper airways enough to produce minor blood-tinged sputum. However, certain scenarios warrant an immediate trip to the emergency department:
- Volume: Coughing up more than a teaspoon of bright red blood, or coughing up blood repeatedly over the course of hours.
- Breathing difficulty: Blood in sputum accompanied by worsening shortness of breath, chest pain, or a feeling that you cannot get enough air.
- Lightheadedness or rapid heartbeat: Signs that blood loss is affecting your circulation.
- Already on blood thinners: If you are taking anticoagulants for any reason and develop hemoptysis during a COVID infection, the bleeding risk is amplified and needs evaluation.
Three patients in one published case series arrived at the emergency department with massive hemoptysis as their only COVID symptom, which underscores that significant lung bleeding can happen even when you feel otherwise fine.2PubMed Central. Case Series of COVID-19 Presenting with Massive Hemoptysis Erring on the side of getting checked is reasonable whenever you are uncertain about the source or severity of bleeding.
How Doctors Investigate the Source
When a COVID patient presents with hemoptysis, the first-line imaging is usually a CT scan of the chest with contrast, often specifically a CT angiogram designed to show blood vessels in detail. This can reveal clots in the pulmonary arteries, areas of alveolar hemorrhage, cavities from secondary infection, or structural abnormalities. In the case report mentioned earlier, CT angiography was what revealed the alveolar hemorrhage in the left lung and pointed clinicians toward a treatable bleeding vessel.3PubMed Central. Haemoptysis as the first presentation of COVID-19: a case report
Bronchoscopy, which involves threading a thin camera into the airways, is the most direct way to locate a bleeding site and potentially treat it. But as noted earlier, the aerosol risk during COVID made it a last resort rather than a first step.4PubMed Central. Spontaneous Hemoptysis in a Patient With COVID-19 When imaging was sufficient to guide treatment or when bleeding stopped on its own, many clinical teams opted to skip bronchoscopy altogether. This pragmatic shift was a notable departure from pre-pandemic algorithms for hemoptysis evaluation, where bronchoscopy played a central diagnostic role.
Treating Hemoptysis in COVID Patients
Treatment depends entirely on the cause and severity. For mild cases where blood-streaked sputum is driven by mucosal irritation from intense coughing, managing the cough itself and supporting hydration is often enough. Codeine-based cough suppressants are sometimes used to reduce the mechanical trauma of repeated forceful coughing, though this is a balancing act since suppressing cough too aggressively in a patient with thick secretions can cause other problems.
For hemoptysis driven by pulmonary embolism, the treatment is anticoagulation, sometimes with an initial period of more aggressive clot-busting therapy if the clot burden is large. If the source is a fungal infection like aspergillosis, antifungal medications are started urgently. And when bleeding is massive or life-threatening regardless of the underlying cause, interventional radiology can perform bronchial artery embolization: threading a catheter through the blood vessels to the source of bleeding and blocking it off with tiny particles or coils. This was the technique that successfully stopped the hemorrhage in the patient whose hemoptysis was the first sign of COVID.3PubMed Central. Haemoptysis as the first presentation of COVID-19: a case report
Does Hemoptysis Predict a Worse Outcome
The evidence on this is mixed and somewhat limited by sample size, since hemoptysis was uncommon enough that most large COVID outcome studies did not have enough cases of it to draw strong conclusions. What is clear is that massive hemoptysis from any cause is a medical emergency with significant mortality, and that remains true when COVID is the trigger. Milder hemoptysis in an otherwise stable COVID patient does not appear to carry the same weight as, say, low oxygen levels or rapidly worsening shortness of breath, which are the better-established markers of severity.
That said, hemoptysis in a COVID patient should always prompt investigation because it can be the visible tip of a more dangerous process happening underneath. A small amount of coughed-up blood might be the first clue to a pulmonary embolism or a fungal co-infection that, if caught early, is treatable. Ignoring it because the volume seems small is not a good strategy.
Post-COVID Lung Healing and Residual Bleeding
Most people who experience minor hemoptysis during acute COVID find that it resolves as the infection clears and the lungs heal. The alveolar-capillary barrier, while fragile, is capable of repair in most cases. For patients who had more severe lung damage, particularly those who spent time on ventilators, recovery takes longer and may involve persistent cough and occasionally blood-tinged sputum for weeks after the acute illness has passed.
The lung remodeling described in pathology studies of fatal cases, including scarring and changes to blood vessel structure, represents the far end of the damage spectrum.1PubMed Central. Lung epithelial and endothelial damage, loss of tissue repair, inhibition of fibrinolysis, and cellular senescence in fatal COVID-19 Survivors with significant lung scarring (pulmonary fibrosis) may deal with ongoing respiratory symptoms, and in rare cases, the structural changes to blood vessels in the lungs can leave those areas more prone to bleeding in response to future respiratory infections or physical stress. If you had COVID-associated hemoptysis and continue to see blood in your sputum weeks later, follow-up imaging is warranted to check for residual damage, clots, or complications that might need treatment.