Is Shortness of Breath a Sign of Cancer?

This page is for people who feel short of breath and wonder whether it could be cancer. It covers when to get help right away, how cancer can affect breathing, and what a visit may involve.

Shortness of breath is not usually cancer on its own. MedlinePlus lists many causes. Lung problems include a blood clot in the lung, COPD (chronic obstructive pulmonary disease, a long-term lung disease) and pneumonia. Heart problems include angina, heart attack, heart failure and heart rhythm problems. Other causes include allergies, obesity, anxiety and panic attacks, and anemia (a low red blood cell count). Lung cancer can be part of the picture. The American Cancer Society lists shortness of breath among the most common symptoms of lung cancer, alongside others such as a cough that does not go away or gets worse.

Breathlessness is an emergency when it comes on suddenly or is severe. It is also an emergency when it arrives with chest pain or blood.

• Call 911 if… breathing difficulty comes on suddenly, or is bad enough that it is hard to talk. MedlinePlus gives both as reasons to call 911. The American Cancer Society adds shortness of breath that is severe or does not get better with rest, and new wheezing that makes it hard to breathe.
• Call 911 if… breathlessness comes with chest pain, tightness or pressure that starts suddenly, is severe, lasts more than a few minutes, or comes and goes. The American Cancer Society adds feeling you might pass out, or feeling confused. MedlinePlus adds bluish lips or fingernails, a sign of shock.
• Call 911 if… breathlessness comes with coughing up blood, or with chest pain that worsens with a deep breath or a fast or irregular heartbeat. CDC lists these as possible signs of a blood clot in the lung, which needs immediate medical attention.
• Call your doctor or care team today if… one leg or arm is swollen, painful or tender, with skin that is warm, red or discolored. CDC says to alert your doctor as soon as possible about these signs of a clot in a deep vein. If breathing trouble or chest pain comes with them, call 911.
• Call your care team right away if… your face, neck, arms or upper chest are swelling. The American Cancer Society explains that a tumor can press on the large vein that drains the head and arms. This is called superior vena cava syndrome. It can become life-threatening and needs to be treated right away. If it comes with trouble breathing, call 911.
• Contact your doctor soon if… you are short of breath at rest or after only slight activity. The same goes if it wakes you at night, you need to sleep propped up, or it keeps getting worse. MedlinePlus lists these as reasons to see a provider.

The American Cancer Society describes several ways cancer can affect breathing. A tumor in or near the lungs may partly or fully block an airway. Fluid can collect in the layers around a lung, called a pleural effusion, and press on the lung so you cannot take a full breath. Anemia, pneumonia and blood clots in the lungs can add to breathlessness, and some cancer medicines can cause a reaction that makes you short of breath. That is why timing matters. Breathlessness during treatment, after treatment, or with a known cancer history may lead to a different workup than breathlessness in an otherwise healthy person.

A breathing change matters more when:

• It is new, unexplained, or getting worse.
• It happens at rest, or limits normal activity.
• It comes with cough, chest discomfort, fever, swelling, dizziness, weight loss, or coughing up blood. These patterns do not prove cancer. They do give a clinician reasons to check the lungs, heart, blood counts, and oxygen level.

A clinician may ask how long you have had trouble breathing, when it started, and what makes it worse. They may also ask about smoking history, recent infections, medicines, cancer treatment, and clot risk. MedlinePlus lists tests that may follow. These include a blood oxygen check, blood tests, a chest x-ray and a chest CT scan. Heart tests and lung function tests may also be done.

A short symptom timeline is often more useful than a perfect medical explanation. Write down when it started and whether it is changing. Note what makes it better or worse, and what else changed then. Include medicines, recent infections, recent procedures, and any cancer treatment history if those apply.

This page can help you see why the symptom may deserve attention, and which details are useful to share. It cannot tell you whether your symptom is cancer, and it cannot replace an exam or testing. MedlinePlus says many causes of breathing trouble are not dangerous and are easily treated. But breathing trouble that is new or getting worse may be due to a serious problem. MedlinePlus says to contact your provider for any breathing difficulty.

• MedlinePlus — Breathing difficulty
• American Cancer Society — Shortness of Breath
• American Cancer Society — Signs and Symptoms of Lung Cancer
• CDC — Blood clots and cancer
• MedlinePlus — Shock
• National Cancer Institute — Symptoms of Cancer