Medical Oncologist
Lung reactions
Breathlessness and Cough on Targeted Therapy — Ruling Out ILD
New breathlessness or a dry cough that starts during targeted therapy is not always a harmless side effect. It can be the first sign of ILD — drug-induced inflammation of the lung — and that needs to be assessed the same day, not at your next scheduled visit.
Medically reviewed by Dr. Bharati Devi Gorantla, Medical Oncologist, MBBS · MD · DM (Adyar, Chennai) · ECMO · MRCP SCE (UK) · Last reviewed August 2026
- ILD is a known risk — Drug-induced lung inflammation is a recognised side effect of several targeted therapies used in lung and other cancers.
- The symptom is the signal — A new dry cough or breathlessness that starts during treatment is the first thing your team needs to hear about.
- Early detection changes outcomes — ILD caught early is manageable. Delay is what allows a mild reaction to become dangerous.
- Not every cough is ILD — Your team needs to rule it out — not assume it — before anything can be managed safely.
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New breathlessness or a dry cough during targeted therapy can be drug-induced interstitial lung disease, or ILD. NCCN and ESMO guidance treats any new respiratory symptom during targeted therapy as needing prompt assessment to rule out lung inflammation. Do not wait for your next appointment — call your team today.
If a symptom below applies to you, do not wait for a callback. Call 1800-202-8726 or go to your nearest emergency department.
How do you tell an ordinary symptom from something that needs urgent review?
| Feature | Less urgent — but still report at next visit | Needs same-day urgent review |
|---|---|---|
| Breathlessness | Only on significant exertion, unchanged since before treatment | New, or clearly worse than before, with everyday activity or at rest |
| Cough | Productive, with mucus or phlegm, not changing | Dry, persistent, new since starting targeted therapy |
| Fever | Absent | Present alongside any new respiratory symptom |
| Chest discomfort | Absent | New tightness or pain alongside breathlessness or cough |
| Response to rest | Improves after sitting quietly for a few minutes | Little improvement after rest, or getting worse |
| Typically starts | Can occur at any point during treatment | Commonly weeks to months after starting targeted therapy, but can appear earlier or after a dose change |
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Dr. C. Raghavendra Reddy
MBBS(Gold Medal), DNB(General Medicine), DM(Medical Oncology)(Gold Medal)
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Dr. Bharati Devi Gorantla
MBBS, MD(General Medicine), DM(Medical Oncology)(Adyar,Chennai), ECMO, MRCP SCE(UK)
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Dr. Owais Mohammed
MBBS, MD (General Medicine), DrNB (Medical Oncology), ECMO, MRCP SCE (Medical Oncology) (UK)
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What can you do at home while you wait for advice?
If your symptoms are mild and not worsening, sit upright and rest. Avoid any activity that makes the breathlessness worse while you wait to speak to your team.
Do not take cough suppressants or decongestants without asking your oncology team first. These do not treat lung inflammation and can mask the worsening your team needs to track.
Note when the symptom started, whether it is improving or getting worse, and whether anything brings it on or relieves it. Your team will ask these questions when you call.
**Call your team today if breathlessness or cough is new, has increased since yesterday, or comes with any fever or chest tightness — even if it feels mild.**
Did you know?
Drug-induced lung inflammation can appear identical on a CT scan to infection, fluid around the lungs, or disease progression — which is why your team needs imaging and sometimes a specialist respiratory review before they can name the cause.
Telling your oncologist early is what keeps all the treatment options open.
Source: ESMO Clinical Practice Guidelines: Targeted Therapy Toxicity Management
Questions patients and families ask most
What exactly is ILD and why does targeted therapy cause it?
ILD stands for interstitial lung disease. In this context it means inflammation of the tissue between the air sacs in your lungs, caused by the drug rather than by infection or the cancer itself. Targeted therapies work by blocking specific signals that cancer cells rely on to grow. In some people, those same signals also play a role in protecting lung tissue. When they are blocked, the immune system or the lung cells can respond with inflammation. Not everyone who takes these medicines develops ILD, and your team will know whether the drug you are on carries a recognised risk.
Does ILD mean I have to stop my targeted therapy permanently?
Not necessarily. The decision depends on how severe the inflammation is and how well it responds to treatment. Milder reactions are sometimes managed with a pause and monitoring, with a possible restart once you have recovered. More severe reactions may mean stopping the drug and switching to an alternative. Your oncologist will weigh the risk of continuing against the benefit the treatment is providing for you. Reporting symptoms early is what keeps the milder options available — a severe reaction that was not reported promptly leaves fewer choices.
Can ILD look like something else on a scan?
Yes, and this is one of the reasons your team takes new respiratory symptoms seriously rather than assuming a cause. Drug-induced lung inflammation can appear very similar to infection, fluid around the lungs, or disease progression on a CT scan. Your oncologist will typically need blood tests, a scan, and sometimes a specialist respiratory opinion before they can say with confidence what is causing the change. This is not delay for its own sake — it is what stops the wrong treatment being started.
Is a dry cough always a sign of ILD?
No. A dry cough has many causes, and most coughs during cancer treatment are not ILD. What matters is whether the cough is new since starting targeted therapy, whether it is getting worse rather than staying the same, and whether it comes with breathlessness, fever or chest discomfort. A productive cough with phlegm that has been present for some time and is not changing is less likely to be drug-induced, but still worth mentioning at your next appointment. A cough that is new, dry, persistent and worsening since starting treatment is worth reporting the same day.
We live far from the hospital. What should we do if symptoms worsen at night?
If symptoms worsen rapidly — you become breathless at rest, cannot finish sentences, or notice blue or grey discolouration around the lips or fingernails — go to the nearest emergency department rather than waiting to reach your oncology team. Let the emergency doctors know what targeted therapy you are taking and when symptoms started. If symptoms are mild and stable overnight, contact your oncology team as early as possible the next morning. Keep the name of your drug and your team's contact number somewhere easy to find so you are not searching for them in a stressful moment.
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Common questions
Frequently asked questions
How quickly can ILD develop on targeted therapy?
ILD most often appears weeks to months after starting treatment, but it can develop at any point — including early in treatment or after a dose change. Because the timing is unpredictable, any new respiratory symptom during targeted therapy is worth reporting promptly rather than watching at home. NCCN and ESMO both recommend that new breathlessness or cough during targeted therapy be assessed rather than assumed to be minor.
Will I need a CT scan to rule out ILD?
Usually yes. A high-resolution CT scan of the chest is the main way doctors identify the pattern of changes that suggest drug-induced lung inflammation, alongside blood tests. CION coordinates CT imaging through partner imaging centres, so ask your care coordinator how quickly this can be arranged if your team requests it. The scan result, combined with your symptoms and blood tests, is what guides the decision about your treatment.
Should I stop my targeted therapy now while I wait to be seen?
Do not stop without speaking to your oncology team first. Stopping without guidance can create its own risks, and your team may want you to pause rather than stop, or to continue while they investigate, depending on how mild your symptoms are. Call your team and describe what you are experiencing. They will tell you whether to continue, pause, or go to emergency care. If you cannot reach them and your symptoms are severe or worsening, go to the emergency department and tell them which drug you are taking.
Could breathlessness be caused by something other than ILD?
Yes, and that is exactly what your team needs to determine. Breathlessness during cancer treatment can have several causes — anaemia, fluid around the lungs, infection, the cancer itself, or a blood clot in the lungs, which is its own emergency. This is why your team will not assume it is ILD without investigating, and why early reporting matters. Calling early means the right cause is identified and the right treatment given, rather than time being lost.
What will happen when I call my oncology team?
Your team will ask when the symptom started, how much it has changed, whether you have a cough, fever or chest discomfort, and whether you are breathless at rest or only with activity. Depending on your answers you may be asked to come in the same day, or directed to emergency care if symptoms sound severe. You will likely need blood tests and a chest CT scan. It helps to have the name of your drug and a brief note of when symptoms started before you call.