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Lung GVHD: bronchiolitis obliterans explained | CION Cancer Clinics
Lung GVHD, most often called bronchiolitis obliterans syndrome, is when donor immune cells scar the small airways after a donor stem cell transplant. It starts quietly, with breathlessness on effort or a dry cough that stays. Breathing tests pick it up early, and treatment aims to stop further damage. This page explains the signs, the tests, the treatment and what it cannot tell you. At CION Cancer Clinics, our haematology team assesses whether a transplant or CAR-T fits your situation and coordinates care with qualified centres.
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Medically reviewed by Dr. Basudev PokhrelConsultant Haematologist · last reviewed September 2026, next review due September 2027
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On this page
- What is lung GVHD, and what is bronchiolitis obliterans?
- What are the early signs of lung GVHD?
- How do doctors check for bronchiolitis obliterans?
- What do the words on a breathing test report mean?
- How is lung GVHD treated, and what can treatment do?
- What do families often believe about breathlessness after transplant?
- Common questions about lung GVHD
The short answer
What is lung GVHD, and what is bronchiolitis obliterans?
Lung GVHD is when immune cells from your donor attack the small airways of your lungs after a donor stem cell transplant. The form doctors name most often is bronchiolitis obliterans syndrome, or BOS, where those tiny airways slowly scar and narrow, so air gets in but struggles to get out.
Why it matters to catch it early
The scarring builds up quietly. Many people feel only a little short of breath at first and put it down to being unfit after a long hospital stay. By the time breathlessness is obvious, some of the airway damage cannot be reversed. Treatment works mainly by stopping it getting worse, which is why your transplant team checks your breathing even when you feel well.
Who is more likely to get it
It is a form of chronic GVHD, the longer-lasting kind. It usually shows up months after the transplant, not in the first few weeks. It is more likely in someone who already has chronic GVHD in the skin, mouth or eyes. It is uncommon overall, and most people who have a donor transplant never develop it.
What it is not
A cough after transplant is far more often an infection than GVHD. Infections need a different treatment, and steroids given for the wrong reason can make an infection worse. That is why your team rules infection out first.
This page applies to donor (allogeneic) transplants. A transplant using your own stem cells does not cause GVHD.
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When breathlessness cannot wait
If you suddenly become breathless at rest, your lips look blue or grey, you have chest pain, or you have a fever with a cough, go to the nearest emergency department now or call 108. Say that you have had a donor stem cell transplant and are on medicines that lower immunity. Do not wait for your next clinic visit, and do not stop or change any medicine on your own.
Not sure whether this applies to you?
Ask an oncologistWhat to watch for
What are the early signs of lung GVHD?
Early signs are mild and easy to explain away. Tell your transplant team about any of these, even if they seem small.
Breathless on effort
Climbing stairs, walking to the market or carrying shopping leaves you more out of breath than it did a few weeks ago. The change is gradual, so compare with how you managed a month back.
A dry cough that stays
A cough with little or no phlegm that does not settle, and is not linked to a cold or fever. It may be worse in the morning or when you exert yourself.
Wheezing
A whistling sound when you breathe out, or a tight feeling in the chest. It can be mistaken for asthma, especially in someone who never had asthma before.
Sometimes nothing at all
Some people have no symptoms while their breathing tests are already falling. This is the reason for regular tests after transplant.
Tell your team if you also have
- Dry eyes or a dry, sore mouth
- Tight or thickened skin
- Tiredness that is getting worse
Finding out
How do doctors check for bronchiolitis obliterans?
A breathing test
You blow as hard and as fast as you can into a tube. This is called spirometry. It shows how quickly air leaves your lungs, and a fall compared with your earlier tests is often the first clue.
A CT scan of the chest
Pictures are taken while you breathe in and again after you breathe out. Trapped air shows up as patchy darker areas on the breath-out pictures.
Ruling out infection
Sputum and swab tests, blood tests and sometimes a camera test of the airways look for an infection that could explain the symptoms instead. This step matters before any stronger treatment.
Putting it together
The diagnosis usually rests on the pattern across tests, alongside GVHD elsewhere in the body. A lung biopsy is rarely needed.
On your report
What do the words on a breathing test report mean?
- FEV1
- How much air you can blow out in the first second of a hard breath. It is the number your team watches most closely over time.
- Obstruction
- Air is having trouble getting out of the lungs because the airways are narrowed. It is the pattern bronchiolitis obliterans causes.
- Air trapping
- Air stays in the lungs after you breathe out. On a CT report it describes the patchy areas seen on the breath-out pictures.
- BOS
- Bronchiolitis obliterans syndrome. The name used when the tests fit this condition without a biopsy.
- Reversibility
- Whether your breathing improves after an inhaler during the test. Little change points away from asthma.
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Treatment
How is lung GVHD treated, and what can treatment do?
Treatment aims to stop the scarring from spreading and to protect the breathing you still have. It rarely brings back airways that have already closed, so the earlier it starts, the more it can protect.
The medicines your team may choose
Many centres use a combination of an inhaled steroid, the antibiotic azithromycin used for its calming effect on airways, and montelukast. Steroid tablets are often added when GVHD is active elsewhere too. If the lungs keep worsening, newer medicines such as ruxolitinib or belumosudil may be considered. Your transplant team sets every medicine and every dose. Never start, stop or change one yourself.
Everything around the medicines
Lung rehabilitation, a guided exercise and breathing programme, helps many people do more with the lungs they have. Vaccines, avoiding smoke and cooking fumes, and early treatment of chest infections all matter. Some people need oxygen at home for a time.
What this page cannot tell you
It cannot tell you how your own lungs will do. That depends on how much breathing was lost before treatment began, how GVHD behaves elsewhere, and how you respond. Your haematologist and a lung specialist will explain your picture using your own test results.
CION's haematology team can review your reports and coordinate with your transplant centre and a lung specialist. CION does not perform transplants.Commonly believed
What do families often believe about breathlessness after transplant?
"He is just weak from the hospital stay. The breathlessness will go."
Weakness after transplant is real, but breathlessness that keeps getting worse is a reason to tell the team. A simple breathing test can show whether the airways are involved.
"The inhaler is helping, so we can stop the tablets."
Feeling better usually means the plan is working. Stopping one part of it can let GVHD flare. Ask your team before changing anything.
"A normal chest X-ray means the lungs are fine."
An X-ray often looks normal in early bronchiolitis obliterans. Breathing tests and a CT scan taken on breathing out are much better at picking it up.
"Exercise will strain damaged lungs."
Guided exercise is part of treatment for most people. It strengthens the muscles that help you breathe. Ask for a programme that suits your level.
Questions we are asked
Common questions about lung GVHD
Can bronchiolitis obliterans be reversed?
Airways that have already scarred usually do not open up again. Treatment aims to stop further damage, and many people stay stable for long periods once it starts working. That is why early testing matters so much. Your team will follow your breathing tests to see whether the decline has slowed or stopped.
How often should breathing tests be done after transplant?
It depends on your transplant centre's plan and on whether you have chronic GVHD elsewhere. Tests are usually repeated regularly in the first years after a donor transplant, and more often if a drop is found. Ask your team for the schedule, and keep copies of every report so results can be compared.
Is lung GVHD the same as a lung infection?
No. An infection is caused by a germ and is treated with antibiotics, antivirals or antifungals. Lung GVHD is caused by donor immune cells and is treated by calming the immune system. The symptoms can look alike, so your team checks for infection first, because the treatment for one can worsen the other.
Will I need oxygen at home?
Most people with lung GVHD do not. Oxygen is suggested when tests show your blood oxygen falls too low at rest, while walking or during sleep. If you need it, the team will arrange a concentrator and show you how to use it safely, including keeping it away from cooking flames.
Can I travel from my district for tests, or must I stay in the city?
Many people live outside Hyderabad and travel in for reviews. Breathing tests can sometimes be done closer to home and sent to your team. Discuss what can be done locally, and always carry a summary of your transplant and your current medicines when you travel.
Does air pollution or cooking smoke make it worse?
Smoke and dust irritate airways that are already narrowed. Keep away from cigarette smoke, burning waste, wood or coal stoves and incense in closed rooms. A mask can help on high-pollution days. Nobody in the home should smoke indoors.
Can I get the flu and pneumonia vaccines?
Vaccines are an important part of protecting your lungs after transplant, but the timing and type matter. Some live vaccines are not safe while immunity is low. Your transplant team follows a set re-vaccination plan. Ask them before taking any vaccine, including ones offered at a local clinic.
What should I bring to a CION appointment?
Bring your transplant discharge summary, every breathing test report, chest CT scans on a disc or as reports, and a list of the medicines you take now. If a family member helps with your care, bring them too. It helps the team see the full picture quickly.
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Sources
- National Cancer Institute — Stem Cell Transplants in Cancer Treatment
- Cancer.Net — Graft-Versus-Host Disease
- Leukemia & Lymphoma Society — Graft-Versus-Host Disease
- NHS — Stem cell and bone marrow transplants
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
Acute vs Chronic GVHDWhy lung GVHD belongs to the longer-lasting formChronic GVHD of the Eyes and MouthSigns that often appear alongside lung GVHDRuxolitinib and Second-Line GVHD TreatmentWhat comes next when steroids are not enoughLiving With Chronic GVHDDay-to-day life, work and follow-upGraft-versus-Host DiseaseEvery GVHD guide in one place
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