Is Blood in Sputum a Sign of Cancer?

This page is for anyone who has seen blood in the mucus they cough up and is worried about cancer. It explains what counts, how much blood needs emergency care, the many causes that are not cancer, and what tests come next.

Sputum is the mucus you cough up. Hemoptysis is the medical word for coughing up blood from the airways. MedlinePlus describes what it usually looks like. It is bubbly, because it is mixed with air and mucus. It is most often bright red, though it can be rust-colored. Sometimes the mucus carries only streaks.

One distinction matters early. This is not the same as bleeding from the mouth, throat or gut. Blood from a nosebleed running backward, or from bleeding gums, can end up in a tissue and look identical.

MedlinePlus, the US National Library of Medicine's health site, publishes clear lines for when to act. It does not treat small amounts as nothing.

• Get help right away, per MedlinePlus, for a cough producing more than a few teaspoons of blood. In the US, that means calling 911.
• Get help right away, per MedlinePlus, if blood comes with chest pain, severe shortness of breath, dizziness, lightheadedness, fever, or blood in the urine or stools.
• Get help right away, per CDC, for the signs of a clot in the lung: difficulty breathing, chest pain that often worsens with a deep breath or cough, coughing up blood, or a faster than normal or irregular heartbeat.
• Contact a provider anyway, per MedlinePlus, any time blood is coughed up, even with no other symptoms.

One more pattern is worth naming. MedlinePlus explains that a clot in the lung most often starts as a clot in a deep vein of the leg or pelvis, called a deep vein thrombosis, which breaks off and travels to the lungs. The signs of a leg clot are swelling, pain or tenderness, and skin that is warm, red or discolored. CDC says to alert your doctor as soon as possible about those. If they come with chest pain, trouble breathing or coughing up blood, MedlinePlus says to call 911.

MedlinePlus adds a warning about self-treatment. Cough suppressants may help when the bleeding comes from coughing hard. But they can block the airway, so they should be checked with a provider first.

On outlook, MedlinePlus says it depends on the cause, and most people do well once the underlying problem is treated. It also notes that severe bleeding from the lungs can be life-threatening. That is why a large amount of blood is treated as an emergency. There is no percentage attached, and inventing one would be worse than the silence.

Once emergencies are ruled out, the next question is what is causing the bleeding. MedlinePlus lists fifteen causes. Lung cancer is one of them. The rest fall into three groups.

Infections and airway conditions

• Bronchitis.
• Bronchiectasis, meaning permanently widened airways.
• Pneumonia and other lung infections.
• Tuberculosis.
• Cystic fibrosis.
• Breathing food or other material into the lungs.

Clots, fluid, blood vessel and immune conditions

• A blood clot in the lung.
• Pulmonary edema, meaning fluid in the lungs.
• Inflammation of the lung's blood vessels, called vasculitis.
• Injury to the arteries of the lung.
• Systemic lupus erythematosus.

Medicines, hard coughing and tests

• Blood that is too thin, most often from a blood-thinning medicine above its intended level.
• Irritation of the throat from violent coughing, which produces small amounts.
• Bronchoscopy with biopsy, as a known effect of the test itself.

That last group explains a lot of cases. Violent coughing can irritate the throat enough to bring up small amounts of blood, and a recent procedure can too. It is also worth checking the medicine list before assuming anything, since blood thinners appear on this list in their own right.

NCI's summary on non-small cell lung cancer lists coughing up blood among the most common symptoms at diagnosis. The others it names are a worsening cough, chest pain, weight loss, breathlessness, hoarseness and a general unwell feeling.

That combination is the thing to notice, rather than the blood alone. NCI also describes symptoms from pressure on nearby structures:

• trouble swallowing when the esophagus is squeezed.
• hoarseness when the nerve to the voice box is caught.
• swelling of the face and neck veins when the large vein draining the head is compressed.

Smoking history changes the weight a clinician gives all of this. NCI reports that smoking raises lung cancer risk about tenfold on average against a lifetime nonsmoker. A lifetime nonsmoker is defined as someone who has smoked fewer than 100 cigarettes. NCI also reports that former smokers stay at raised risk for years. For a separate look at the same symptom, see coughing up blood and a persistent cough.

MedlinePlus publishes the questions, which makes them a useful list to prepare against:

• How much blood, and is it large amounts at a time?
• Is it blood-streaked mucus rather than blood alone?
• How many times has it happened, and how often?
• How long has this been going on, and is it worse at any particular time, such as at night?
• What other symptoms are there?
• Is any blood-thinning medicine being taken?

MedlinePlus also suggests keeping track of how long the bleeding continues and how much blood is mixed with the mucus. That record is more useful than a memory of one alarming morning.

A complete physical examination comes first, with the chest and lungs checked. MedlinePlus then lists the tests that may be done:

• Chest x-ray.
• Chest CT scan.
• Bronchoscopy, which looks directly inside the airways.
• Complete blood count.
• Clotting tests such as PT with INR, or PTT.
• Sputum culture and smear.
• A lung scan, pulmonary arteriography, or a lung biopsy.

Which of these gets ordered depends on the pattern, the examination and the risk factors, not on the word "blood" by itself. A clotting test and a blood count answer a different question from a CT scan. The first asks whether the blood itself is behaving. The second asks what the lung looks like. For the broader picture of how symptoms are worked up, see symptoms of cancer.

Set out as actions, the lines above look like this.

• Call 911 if you cough up more than a small amount of blood. MedlinePlus puts its line at more than a few teaspoons. Call 911 too if coughed-up blood comes with chest pain, severe shortness of breath or trouble breathing, a fast or irregular heartbeat, dizziness or lightheadedness, fever, or blood in your urine or stools. Do not drive yourself.
• Call your doctor or care team today if you cough up any blood at all, even a streak, and even with no other symptom. MedlinePlus says to contact a provider any time blood is coughed up. Call today too for swelling, pain or tenderness in one leg or arm with skin that is warm, red or discolored, which can be a clot in a deep vein. If those leg signs come with chest pain or trouble breathing, call 911.
• Ask before you treat it. MedlinePlus warns that cough suppressants can block the airway, so check with a provider first rather than reaching for one.

• https://medlineplus.gov/ency/article/003073.htm
• https://medlineplus.gov/ency/article/000132.htm
• https://medlineplus.gov/ency/article/000156.htm
• https://www.cdc.gov/blood-clots/risk-factors/cancer.html
• https://www.cancer.gov/types/lung/hp/non-small-cell-lung-treatment-pdq