Is interstitial lung disease the same as pulmonary fibrosis?

Not exactly. Pulmonary fibrosis (scarring) is a feature of many ILDs, and IPF (idiopathic pulmonary fibrosis) is one specific, well-known type. ILD is the broader umbrella term covering 200+ conditions, only some of which are predominantly fibrotic.

Can ILD be cured or reversed?

Some can improve or stabilise — particularly inflammation-driven ILD from an identified trigger or an autoimmune disease that responds to treatment. Established fibrosis generally cannot be reversed, but antifibrotic drugs, oxygen and rehabilitation can slow decline and improve quality of life.

Causes include autoimmune/connective-tissue diseases (e.g. rheumatoid arthritis, scleroderma), inhaled organic dusts/moulds/bird proteins, sarcoidosis, certain medications, and occupational dust exposure (asbestos, silica). In IPF, no cause is found. Smoking can cause or worsen some ILDs.

How is ILD diagnosed?

Through a detailed exposure history, lung function tests (a restrictive pattern with reduced gas transfer), high-resolution CT (HRCT), blood tests, and sometimes bronchoscopy or lung biopsy — with the final diagnosis ideally confirmed at a multidisciplinary meeting in an ILD clinic.

Interstitial Lung Disease (ILD): Causes, Diagnosis & Treatment (Singapore)

Q: When should I see a doctor?

See a doctor if you have breathlessness on exertion that is gradually getting worse, or a persistent dry cough lasting more than a few weeks — especially if you have an autoimmune condition or a history of dust, mould or bird exposure. Early specialist referral improves the chance of finding treatable disease.

Written & reviewed by the BestDoctors.sg editorial team · Last updated 3 Sep 2026 · General information, not medical advice

Quick answer. Interstitial lung disease (ILD) is not one disease but an umbrella term for a large group of more than 200 conditions that cause inflammation and/or scarring (fibrosis) of the lung tissue – the interstitium, the tissue around the air sacs. This makes the lungs stiff and less able to move oxygen into the blood, so the main symptoms are gradually worsening breathlessness and a persistent dry cough. Idiopathic pulmonary fibrosis (IPF) is one well-known type, but ILD also arises from autoimmune diseases, inhaled dusts and moulds, certain drugs, and occupational exposures. Some ILDs are treatable or reversible; fibrotic types tend to be progressive. It needs specialist respiratory assessment.

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“ILD” is really a family name, not a single diagnosis – and because the many types differ so much in cause, course and treatment, getting the specific diagnosis right is what everything depends on.

What it is

Interstitial lung disease is a broad family of conditions in which the interstitium – the delicate supportive tissue that surrounds the alveoli (air sacs) and holds the tiny blood vessels of the lung – becomes inflamed, scarred, or both. When this tissue thickens with scar (fibrosis), two things happen. The lungs become stiff and harder to expand, so each breath moves less air; and the barrier that oxygen must cross to reach the bloodstream becomes thicker, so less oxygen transfers with each breath. The result is a lung that works harder for less reward, which is why breathlessness is the defining feature.

The word “interstitial” simply describes where the problem sits – in the tissue between and around the air sacs, rather than in the airways (as in asthma) or the air spaces themselves (as in most pneumonia). Idiopathic pulmonary fibrosis is the best-known single type, but it is only one member of a very large group. Some forms are dominated by inflammation and may settle or improve; others are dominated by established fibrosis and tend to progress. Telling these apart is the whole point of specialist assessment.

Symptoms

The most typical symptom is breathlessness – at first only on exertion, such as climbing stairs or walking uphill, and worsening gradually over months or years. Many people unconsciously slow down or avoid activities to stay comfortable, so the change can be easy to overlook. A second common feature is a persistent dry cough that does not bring up phlegm and does not respond to the usual cough remedies. Other symptoms include tiredness and reduced stamina, unintended weight loss in more advanced disease, and sometimes clubbing of the fingertips – a broadening and rounding of the ends of the fingers and nails that develops slowly.

Because the onset is so gradual and the symptoms are non-specific, ILD is often mistaken at first for normal ageing, being unfit, asthma or a heart problem, which can delay diagnosis. Anyone with breathlessness on exertion that is slowly getting worse, or a dry cough that lasts more than a few weeks, should be assessed by a doctor rather than assuming it is simply age or fitness.

Causes and types

There are many causes, and identifying the driver shapes the treatment. Autoimmune and connective-tissue diseases – such as rheumatoid arthritis, scleroderma (systemic sclerosis) and other rheumatological conditions – can inflame and scar the lungs. Occupational and environmental exposures are another major group: inhaled mineral dusts such as asbestos and silica cause occupational lung diseases like asbestosis and silicosis, while organic dusts, moulds and bird or animal proteins can trigger hypersensitivity pneumonitis, an immune reaction to something repeatedly breathed in at home, work or a hobby. Certain medicines (including some chemotherapy, some heart drugs and some antibiotics) and radiotherapy to the chest can injure lung tissue. Sarcoidosis is a distinct inflammatory condition that often involves the lungs.

In a proportion of cases, no cause can be found despite thorough testing; these are labelled idiopathic. Idiopathic pulmonary fibrosis is the most important of these and tends to be progressive. Because the same scarring can arise from so many directions, a careful search for a cause – including a detailed history of jobs, home environment, hobbies, pets and medicines – is a central part of the work-up.

Who is at risk

ILD can affect anyone, but several factors raise the risk. Older age is the strongest for many of the fibrotic types, which usually appear in later adult life. Smoking is linked to several forms of ILD and worsens outcomes generally. Certain jobs and exposures – construction, shipyard and demolition work, stone and quarry work, farming, and exposure to birds or mould at home – increase risk through inhaled dusts and antigens. Having an autoimmune condition such as rheumatoid arthritis or scleroderma raises the risk of associated ILD. In some types there is a family history, pointing to an inherited tendency. Having a risk factor does not mean ILD will develop, but it makes symptoms worth taking seriously and mentioning to a doctor.

How it is diagnosed

Diagnosis begins with a careful history and examination, including detailed questions about occupation, home and environmental exposures, hobbies, pets, medicines and any autoimmune symptoms; on listening to the chest, a doctor may hear fine crackles. Key tests include lung function tests (spirometry and gas transfer), which in ILD typically show a restrictive pattern with reduced gas transfer; a high-resolution CT (HRCT) scan of the chest, which shows the pattern and distribution of inflammation and scarring in fine detail and is central to diagnosis; and blood tests looking for autoimmune and connective-tissue causes. Oxygen levels may be checked at rest and during a walking test.

In some cases a lung biopsy is needed to confirm the type, obtained through a bronchoscope or, in selected people, by a surgical sample. Because the many types can look similar and the treatment differs so much, the findings are often reviewed by a specialist multidisciplinary team – a respiratory physician, a chest radiologist and a pathologist together, sometimes with a rheumatologist – in a dedicated ILD clinic. This team approach gives the most reliable diagnosis and is well worth the time it takes.

Complications

As scarring advances, ILD can lead to progressive breathlessness and persistently low oxygen levels, which may eventually require supplemental oxygen. Raised pressure in the blood vessels of the lungs, called pulmonary hypertension, can develop and adds extra strain on the right side of the heart. Some people experience flare-ups (acute exacerbations) – a sudden worsening of breathlessness over days, sometimes triggered by infection and sometimes with no clear trigger – which need prompt medical assessment. Reduced lung function can also make ordinary chest infections more serious, which is one reason vaccination and early treatment of infections matter.

Treatment

Treatment depends heavily on the type and cause, which is why getting the specific diagnosis right comes first. Where a trigger is identified – a mould, a bird, an occupational dust or a causative medicine – removing or avoiding that exposure is a cornerstone and can halt or partly reverse the process. For inflammatory and autoimmune-associated ILD, immune-suppressing medicines (such as corticosteroid and other immunosuppressant classes) are used to calm the inflammation. For certain progressive fibrotic types, including IPF, antifibrotic medicines can slow the rate of scarring, though they do not reverse damage already done; these are prescribed and monitored by a respiratory specialist.

Supportive treatments are important whatever the type. Oxygen is prescribed when levels are low, to ease breathlessness and reduce strain on the heart. Pulmonary rehabilitation – a supervised programme of exercise, breathing techniques and education – improves stamina and quality of life. Vaccinations (such as influenza and pneumococcal) help prevent chest infections that can trigger flare-ups. For a selected minority with advanced disease, lung transplant assessment may be considered. Because ILDs are so varied, respiratory-specialist and multidisciplinary care is essential to match treatment to the type.

Living with it

Day-to-day self-care makes a real difference. Stopping smoking is the single most valuable step for anyone who smokes, and avoiding second-hand smoke helps too. Completing and keeping up with pulmonary rehabilitation builds confidence and fitness within safe limits, and staying active at a pace that suits you helps maintain strength and mood. Keep vaccinations up to date, use oxygen as prescribed if it has been recommended, and treat chest infections early. Pacing activities, planning rest, and asking for support – from family, from a respiratory nurse or physiotherapist, and from patient support networks – all help with the emotional as well as the physical side of living with a long-term lung condition. In Singapore, a GP or polyclinic can start the assessment and refer on, and HealthHub offers reliable general information on lung health.

When to see a doctor

See a doctor for breathlessness on exertion that is gradually worsening, or a persistent dry cough that lasts more than a few weeks – especially if you have an autoimmune condition, a dusty or high-exposure job, or a family history of lung fibrosis. Because ILD is easily mistaken for ageing or being unfit, it is better to be checked and reassured than to wait. A GP or polyclinic can arrange initial tests and refer you to a respiratory physician, who can assess the pattern and plan the right investigations.

Red flags – seek prompt or urgent care. Get an urgent medical assessment if you notice worsening breathlessness, a sudden increase in symptoms over days, chest pain, or a fever with new breathlessness. Go straight for emergency help – call 995 – for severe difficulty breathing, breathlessness at rest, or blue lips or fingertips. These can signal a flare-up, an infection or dangerously low oxygen, and need immediate attention.

Related respiratory & lung topics

Sources

American Lung Association — interstitial lung disease: a group of many conditions; types, symptoms, treatments.
HealthXchange (SingHealth) — interstitial lung disease: Singapore patient-facing symptoms and management.
Singapore Medical Journal / SGH — ILD service and multidisciplinary diagnosis; rheumatology-associated ILD.
StatPearls (NCBI) — ILD: inflammation/fibrosis, common types, cough + exertional dyspnoea, clubbing; antifibrotics.

General information only. This guide is general information about a lung or breathing condition and is not a diagnosis or personalised medical advice. See a doctor — a GP or a respiratory physician — for assessment, tests and treatment. Call 995 or go to A&E for sudden severe breathlessness, sudden chest pain with breathlessness, coughing up a lot of blood, or a child with fast/laboured breathing, breathing pauses or blue lips.

Interstitial Lung Disease (ILD) in Singapore