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Shortness of Breath
Cancer and cancer treatment may cause shortness of breath or a feeling of not being able to catch your breath. This is called dyspnea. Learn more about what causes shortness of breath and how it can be managed.
How serious is shortness of breath?
People do not suffocate or die from being short of breath. However, it can be upsetting and can affect your daily life.
Shortness of breath can come on quickly and be severe, or it can be mild and bothersome when doing daily activities. It can limit what you are able to do and can make fatigue, anxiety, and depression worse.
There is also a chance it can be a sign of a more serious problem that needs medical attention, especially if it comes on quickly.
What causes shortness of breath in people with cancer?
You might have shortness of breath for many reasons. You might become short of breath because of your cancer, cancer treatment, or other problems. For example, some cancer treatments can irritate or damage your lungs, making it hard to get enough air. These side effects might come on quickly or develop slowly after treatment is finished.
Cancer blocking your airway
If you have cancer in or near your lungs, the tumor may partly or fully block your airway. This can happen with cancer in your chest or throat, or cancer that has spread to your lungs or other parts of the respiratory system. People with advanced cancer often have shortness of breath.
Infusion or immune reaction to cancer treatment
Certain anti-cancer medicines can cause an infusion or immune reaction when given through an IV (intravenously). These reactions usually happen quickly and can be mild, severe, or even life-threatening at times. They may make you feel short of breath and cause coughing and chest discomfort.
Lung inflammation
Pneumonitis is inflammation of the lungs. It can be caused by radiation therapy to your chest, such as for breast or lung cancer. It can also be caused by some types of chemo, immunotherapy, targeted therapy, or stem cell transplant. Pneumonitis usually goes away on its own, but sometimes it needs medical treatment.
Stiffening or scarring of the lungs
Pulmonary fibrosis is stiffening or scarring of the lungs that makes it hard for your lungs to take in air like they should. It can happen if pneumonitis doesn’t go away after cancer treatment. It usually doesn’t start until months to years after treatment and can continue to get worse over time.
Fluid buildup (effusions)
Effusions are collections of fluid in different parts of your body. Fluid can build up for many reasons, including cancer, blockages in blood vessels or lymph nodes, infection, inflammation, or problems in your heart, liver, or other organs.
There are 3 kinds of effusions that can affect your breathing:
Pleural effusions can build up in the layers around the lungs. When this fluid builds up, it can compress the lungs so that you can’t take a full breath.
Pericardial effusions can form in the layers around the heart, which can prevent the heart from pumping out enough blood. This can cause fluid to back up in the lungs, making you feel short of breath.
Ascites is the buildup of fluid in your abdomen (belly). This can cause your belly to swell and push up on your lungs so that you can’t get a full breath.
Other causes of shortness of breath
Many people with cancer have other symptoms, side effects, or non-cancer health issues that can cause breathing problems:
- Low blood counts (anemia)
- Fatigue
- Pneumonia (lung infection)
- Poor nutrition
- Stress or anxiety
- Blood clots in your lungs
- A history of other lung or breathing problems such as COPD, emphysema, chronic bronchitis, or asthma
Symptoms of shortness of breath
Shortness of breath can be different from person to person. You might only feel short of breath when you’re exercising or going up stairs, or you might have trouble breathing even when you’re resting.
People describe shortness of breath as:
- Not being able to get enough air into their lungs
- Not being able to take a full breath or needing to breathe more often to get enough air
- Tightness or discomfort in your chest
- Feeling like you are smothering, drowning, or suffocating
You might also have chest pain, wheezing, or feel like you’re breathing faster than usual.
Call 911 or go to the emergency room if you have
- Shortness of breath that starts suddenly and doesn’t get better
- Wheezing that you’re not already being treated for
- Trouble speaking because of your shortness of breath
- Chest pain or pressure
- Dizziness or weakness
Medical treatment for shortness of breath
How your shortness of breath is treated will depend on the cause.
- If your shortness of breath is because of a reaction to your treatment, the treatment will be stopped and you will be given medicines to stop the reaction. This might include antihistamines, steroids, or other medicines to help your airway relax.
- If your airway is being blocked by your cancer, you can be given treatments to help shrink the cancer or clear the block in your airway.
- Opioids might be used to help relieve your symptoms, either as pills or in an IV.
- If the level of oxygen in your blood is low, you might be given oxygen therapy.
You might also be referred for pulmonary rehabilitation or exercise training if you are feeling weak and having trouble being active.
How to manage symptoms of shortness of breath
Even if you are receiving medical treatment for your shortness of breath, there are things you or your caregiver can do to make you more comfortable. You can:
- Sit up or raise your upper body by elevating the head of your bed or using pillows behind your back.
- Inhale deeply through your nose and exhale slowly through puckered lips. Exhale for twice as long as it took you to inhale. (This is called pursed-lip breathing.)
- Remove or loosen any tight clothing.
- Try mindfulness and relaxation strategies.
- Try ways to distract yourself, such as listening to music, watching TV, or reading.
- Ask your doctor whether there are medicines or treatments that might help you.
- Avoid smoking, secondhand smoke, and allergens like dust and pet dander.
- Check and replace filters in your heating and cooling systems. Home air purifiers can be helpful, too.
If you have home oxygen, be sure you know how to set it up, use it safely, and what flow rate to use. Do not change the flow rate without first talking to your cancer care team.
When to call your health or cancer care team
Contact your health or cancer care team if you:
- Have trouble breathing at rest or during exercise
- Start wheezing
- Have trouble speaking
- Have chest pain
- Cough up thick, yellow, green, or bloody sputum
- Feel confused or restless
- Written by
- References
Developed by the American Cancer Society medical and editorial content team with medical review and contribution by the American Society of Clinical Oncology (ASCO).
American Society of Clinical Oncology. Shortness of Breath or Dyspnea. Cancer.net. Content is no longer available.
Gardom MR. Pulmonary symptom: Dyspnea. In: Maloney-Newton S, Hickey M, Brant JM (eds.), Mosby’s Oncology Nursing Advisor: A Comprehensive Guide to Clinical Practice. Elsevier; 2024: 386-388.
National Comprehensive Cancer Network (NCCN). Palliative Care. Version 2.2025. Accessed at https://www.nccn.org/professionals/physician_gls/pdf/palliative.pdf on July 28, 2025.
Oncology Nursing Society (ONS). Symptom interventions: Dyspnea. Accessed at https://www.ons.org/pep/dyspnea on July 14, 2025.
Shin J, Kober KM, Yates P, Wong ML, Miaskowski C. Multifactorial Model of Dyspnea in Patients With Cancer. Oncol Nurs Forum. 2023;50(3):397-415. doi:10.1188/23.ONF.397-415.
Last Revised: August 19, 2025
American Cancer Society medical information is copyrighted material. For reprint requests, please see our Content Usage Policy.
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