Can chemotherapy cause shortness of breath?

Yes, shortness of breath can occur during or after chemotherapy, and it can have heart-related and lung-related causes. Certain cancer treatments may affect heart muscle or rhythm, or trigger inflammation and scarring in the lungs, all of which can make breathing harder. ^{[1] [2]} Some targeted therapies, immunotherapies, and radiation can also contribute to breathing problems. ^[1]

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Why chemo can cause breathlessness

• Heart effects (cardiotoxicity). Some treatments can weaken the heart muscle (cardiomyopathy), inflame the heart (myocarditis or pericarditis), change valve function, cause rhythm problems (arrhythmias), or lead to fluid around the heart (pericardial effusion). These can present as shortness of breath, especially with activity or when lying flat. ^{[2] [3]}

• Lung effects (pulmonary toxicity). Several anticancer agents are linked to inflammation of the lung (pneumonitis), interstitial lung disease (ILD), scarring (fibrosis), fluid in the lungs, bronchospasm during infusions, or even acute lung injury. Breathlessness may come with dry cough, fever, or chest discomfort. Bleomycin, cyclophosphamide, carmustine, lomustine, mitomycin-C, and some targeted therapies (e.g., KRAS or MET inhibitors) are known examples. ^{[4] [5] [6] [7] [8]}

• Other contributors. Prior chest radiation, pre-existing lung disease, high cumulative drug doses, kidney dysfunction, oxygen exposure at high concentrations, and concomitant use of other lung-toxic agents can increase risk. ^{[9] [7]}

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Red flags: when to seek urgent care

Seek immediate medical attention or go to an Emergency Department if you have:

• New or worsening shortness of breath, especially if sudden or severe. ^[10]
• Shortness of breath with chest pain, fast heartbeat, fainting, blue lips or nails, confusion, or fever. ^{[11] [10]}
• Trouble breathing at rest or with simple tasks after recent chemo. ^[12]

Many treatment programs advise reporting chest pain or breathlessness right away because these symptoms can signal serious heart or lung complications. ^{[11] [13] [14]}

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How clinicians typically evaluate breathlessness during chemo

• Clinical assessment and monitoring. Doctors often check oxygen levels, listen to the lungs and heart, and review recent treatments and risk factors. ^[15]
• Imaging and tests. Chest X-ray or CT scan, pulmonary function tests (PFTs), echocardiogram, ECG, and lab work may be ordered to pinpoint heart vs. lung causes. ^[16]
• Treatment adjustments. If drug-induced lung toxicity is suspected, prompt withholding or discontinuation of the offending agent is common, with careful consideration of the cancer treatment plan. ^{[16] [15]}
• Medications and supportive care. Corticosteroids are frequently used for inflammatory lung toxicity, though evidence is largely observational; supplemental oxygen and supportive measures may be provided. ^{[16] [17]}
• Specialist input. Early referral to a respiratory (pulmonary) specialist may be considered for complex or severe cases. ^[15]

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Practical coping strategies for breathlessness

These techniques do not replace medical care, but they can help you feel more in control:

• Positioning and pacing. Lean forward slightly when sitting, pace activities, and plan your day to conserve energy for essential tasks. This can reduce the sensation of breathlessness during routine activity. ^{[18] [19]}
• Breathing techniques. Focused breathing, such as pursed‑lip breathing (inhale through the nose, exhale slowly through puckered lips), and timing your breaths with movement can ease symptoms. ^[18]
• Relaxation to reduce anxiety. Anxiety can worsen breathlessness; try music, guided imagery, meditation, or prayer to calm your mind during episodes. ^[20]
• Pulmonary rehab-style tips. Breath training and gentle muscle relaxation exercises may help you manage episodes more effectively. ^[21]
• Safety at home. Use shower aids, sit for longer tasks, and avoid bending/straining without planning your breaths to prevent sudden dyspnea and fatigue during self-care. ^[22]

Always tell your care team if breathlessness is new or getting worse; more treatments are available beyond the basics above. ^[19]

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Common chemo and targeted agents linked to lung issues

While not exhaustive, the following are illustrative examples associated with pulmonary toxicity:

• Bleomycin: ILD, eosinophilic pneumonia, organizing pneumonia, pulmonary edema; higher risk with high cumulative dose, prior chest radiation, high oxygen exposure. ^{[4] [9]}
• Cyclophosphamide: ILD, eosinophilic pneumonia, diffuse alveolar damage, pulmonary fibrosis. ^[5]
• Carmustine and Lomustine: ILD, eosinophilic pneumonia, organizing pneumonia, pulmonary fibrosis; risk increases with cumulative dose and prior lung issues. ^[6]
• Mitomycin‑C: Interstitial pneumonitis and ILD. ^[7]
• Targeted therapies (examples): KRAS inhibitors (e.g., sotorasib) and MET inhibitors (e.g., tepotinib) have reported ILD/pneumonitis and respiratory failure in rare cases. ^[8]

If you are receiving any of these or similar agents, your team may monitor your lung function and advise early reporting of respiratory symptoms. ^[23]

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Key takeaways

• Shortness of breath during chemo can be related to heart or lung effects, and both can be serious if ignored. ^{[2] [16]}
• Urgent symptoms like sudden dyspnea, chest pain, fast heartbeat, blue lips, fainting, or confusion need emergency care. ^{[10] [11]}
• Management often includes stopping the suspect drug, supportive care, and sometimes corticosteroids, plus targeted testing to identify the cause. ^{[16] [17]}
• Simple coping strategies pursed‑lip breathing, positioning, pacing, and relaxation can help you feel more comfortable while your care team investigates. ^{[18] [20] [19] [21]}

If you’re experiencing breathlessness during treatment, loop in your oncology team promptly so they can assess and tailor care to your specific situation. ^[12]