Interstitial lung disease (ILD)

The interstitium is the fine scaffolding of tissue that sits between the lungs' tiny air sacs and holds them in place. Interstitial lung disease, or ILD, is the umbrella name for a large family of conditions in which that tissue becomes inflamed and, with time, scarred. Fibrosis is the medical word for scarring, which is why the problem is so widely known as pulmonary fibrosis. Once scarred, the tissue is thicker and stiffer, oxygen crosses into the bloodstream less easily, and breathing costs more effort.

Pulmonary fibrosis, in other words, is one form ILD takes rather than a condition apart from it. ILD has many causes. Sometimes no cause can be found, which is the case in idiopathic pulmonary fibrosis. Sometimes the cause is exposure to particular dusts or medicines, and sometimes it is another illness. The connective tissue diseases are one of the most important causes of all, and they are the reason a rheumatologist may be involved.

An overactive immune system underlies several rheumatic conditions, and the harm it does to the joints or the skin it can also do to the lungs, inflaming and then scarring them. In someone with one of these conditions, then, breathlessness or a cough gets the same attention as a painful joint.

Among the conditions on a rheumatologist's watch list are:

• Systemic sclerosis (scleroderma), where involvement of the lungs is common, so everyone with it is screened
• Rheumatoid arthritis, where the joints are not the only site: the lungs can be affected too
• The inflammatory myopathies (myositis), where a particular risk to the lungs goes with certain antibody patterns
• Sjögren's syndrome: for some people the lungs are part of it
• Mixed and undifferentiated connective tissue disease, where in the mixed form the lungs are involved about as often as in systemic sclerosis, so everyone with it is screened too
• Sarcoidosis, itself among the commoner forms of ILD

ILD can be developing quietly before it causes any obvious symptom, so in the conditions that carry a higher risk, thinking about the lungs from the very start is part of what specialist rheumatology care means.

Two symptoms stand above the rest:

• Breathlessness that is new or getting worse, most of all on exertion such as a hill or a flight of stairs
• A dry cough that persists, three weeks or more, and will not settle

Tiredness, less stamina than before, and a sense of being unable to fill the lungs can come with them. They tend to creep up gradually, which makes them easy to blame on age, on being out of condition or on a cold that has hung around. For someone with a connective tissue disease that is precisely the wrong assumption: new or worsening breathlessness, or a cough that persists, should always be looked into rather than written off as unfitness, because lung involvement is far better caught early. Breathlessness severe enough to leave you gasping, choking or unable to speak is a 999 or A&E emergency; breathlessness that is new or getting worse is a same-day matter (in pregnancy, breathlessness that comes on suddenly, or when you lie down, or with dizziness, is for your midwife or maternity unit straight away), and a slow drift one to raise promptly, as the section on seeking help below sets out.

A careful history and examination come first, with the chest listened to and the oxygen level read from a small clip on a fingertip, at rest and sometimes during a six-minute walk. Two investigations do most of the work:

• Lung function tests (breathing tests): the capacity of the lungs, and the ease with which oxygen reaches the blood, are what these measure
• High-resolution CT of the chest: this detailed scan reveals where inflammation or scarring is, what form it takes and how much there is

In systemic sclerosis everyone has a CT scan and breathing tests at diagnosis, whether or not there are symptoms, and the breathing tests are then repeated every year, as part of the annual screen for raised pressure in the blood vessels of the lungs, or, once ILD has been found, every three to six months for the first few years and at least every six to twelve months after that. In mixed connective tissue disease a CT scan at diagnosis is advised for everyone too, and in the myopathies for those at higher risk (certain antibodies, arthritis, the roughened fingertips called mechanic's hands, or a rash with little muscle weakness); in rheumatoid arthritis and Sjögren's syndrome a scan may be offered to those with risk factors, so that a change is picked up early rather than waited for. Antibody tests on the blood help to identify the rheumatic condition behind it and to judge how likely the lung disease is to progress. Joints that are affected as well can be assessed for inflammation: point-of-care ultrasound is part of the consultation with Dr Borukhson, and the ultrasound clinic page covers it.

What drives the disease, and how it is behaving, set the course of treatment, and respiratory specialists always share in it.

In connective tissue disease-associated ILD the main problem is often inflammation, and where that is so, treatment is aimed at quietening the immune response. A common choice is mycophenolate; cyclophosphamide or rituximab, a biologic, are among the others that may be considered for selected cases; in systemic sclerosis with early, widespread skin disease and either raised inflammatory markers or skin that has recently got worse, tocilizumab, another biologic, is used; and a corticosteroid such as prednisolone is sometimes used alongside them, though with care. If the scarring goes on advancing even though the inflammation is being treated, an antifibrotic medicine such as nintedanib may be added to slow the rate of scarring; in systemic sclerosis it can be started alongside mycophenolate from the outset where the scarring is already extensive. Pirfenidone, another antifibrotic, belongs mainly to idiopathic pulmonary fibrosis, though it is an option in some rheumatoid arthritis-related ILD. None of these is prescribed lightly: each is a specialist medicine, chosen for the person taking it, given under close supervision and monitored regularly.

Medicines are not the only help. Many people are helped to stay active and breathe more comfortably by pulmonary rehabilitation, a supervised programme of exercise and education, and oxygen is prescribed where breathlessness and the oxygen level call for it. The lungs are also protected by not smoking, by up-to-date vaccinations and by getting help for a chest infection the same day it starts, from your GP, your rheumatology or respiratory team, or NHS 111, as the When to seek help section says.

ILD lies where rheumatology and respiratory medicine meet, and it is managed best when the two specialties pull together. Dr Borukhson practises within a world-renowned tertiary centre; the respiratory physicians, radiologists and other specialists ILD may need are consultant colleagues she works alongside. A respiratory physician can join your care early where that is useful, and a multidisciplinary team meeting (MDT) is there for the most complex cases, where rheumatologists, respiratory physicians, radiologists and others settle the plan between them, so that screening, monitoring and treatment can be agreed together, and agreed promptly.

Alongside the treatment, there are things you can do for yourself that help to protect the lungs and your health more broadly:

• If you smoke, stop. Nothing does more for the lungs, and the NHS stop-smoking services are there to help.
• Keep moving, as far as you are able. Stamina is kept up by regular gentle activity and by any exercises you were set in pulmonary rehabilitation; pace yourself, and build up a little at a time.
• Protect yourself from chest infections. Have every vaccination your team recommends, the flu, COVID-19, pneumococcal and RSV ones among them, where you are eligible, and get a chest infection assessed the same day, as soon as it starts, by the routes the When to seek help section gives.
• Keep to the monitoring. A change is caught early by repeating the breathing tests and scans over time, even while you feel well.
• Talk to your team before trying for a baby. Mycophenolate and nintedanib are among the medicines that are avoided in pregnancy: they are stopped beforehand, with a gap before conception. Our guide to arthritis, autoimmune conditions and pregnancy covers planning a pregnancy, and what to do if one has already begun.
• Mind your mood as well. A lung condition can weigh on you, and help with how you are coping belongs in good care.

Long spells of stability are common in ILD, most of all when it was found early and has been closely monitored since.

ILD can change over time, and when it does some symptoms need a prompt response, not a place on the list for the next routine review.

Treat any of these as a 999 or A&E emergency: call 999 and do not drive yourself to A&E.

• Severe illness with suspected sepsis: a high fever with shaking, confusion, rapid breathing, or feeling dramatically worse over hours
• With a fever or feeling unwell, a rash that does not fade when you press it, a stiff neck with eyes that cannot bear bright light, or skin, lips or tongue turning blue, grey, pale or blotchy, since these can be signs of meningitis or sepsis; on black or brown skin the rash and the change of colour may be easier to see on the palms of the hands or the soles of the feet
• Chest pain that is crushing, tight or like a pressure, that spreads to an arm, the jaw, the neck, the stomach or the back, that comes with breathlessness, sweating, feeling sick or feeling light-headed, or that came on suddenly and does not go away
• Breathlessness that is severe, with gasping, choking or no breath to get words out; or coughing up blood
• Palpitations happening now that do not stop, or that come with chest pain, breathlessness, feeling faint or fainting, since a heart whose muscle or rhythm is affected has to be checked at once
• A blackout, since raised pressure in the blood vessels of the lungs, which ILD can bring about, can be behind it
• Sudden weakness or numbness on one side, a drooping face or difficulty speaking, a sudden severe headache, sudden confusion or a seizure, or sudden loss of vision, any of which can be a stroke, even if it stops after a short time
• An eye that suddenly and completely loses its sight
• Vomiting that will not let your tablets stay down, or, during an illness or after an injury, becoming very drowsy or confused, or fainting, after more than a few weeks on steroid tablets, or repeated courses or injections in the past year, since your body may be running short of cortisol and the steroid may need to be given by injection; have your NHS Steroid Emergency Card ready
• Sudden severe pain in the abdomen or back, since the pancreas can react to prednisolone
• Lips, mouth, throat or tongue that suddenly swell, a throat that feels tight, very fast breathing or a struggle to breathe or to swallow, skin, tongue or lips turning blue, grey or pale (on black or brown skin this may be easier to see on the palms of the hands or the soles of the feet), becoming suddenly very confused, drowsy or dizzy, or fainting and not being able to be woken, since this can be a severe allergic reaction, anaphylaxis, which can follow a dose of any medicine
• Vomiting blood, or bleeding from the back passage that is heavy or will not stop, most of all with faintness, confusion or pain in the abdomen, or vomit that is black or dark brown, since a stomach ulcer on prednisolone can bleed
• Serious harm you have already done to yourself, such as an overdose, or a feeling that you may be about to harm yourself, since you need help to keep you safe now

Any of these needs an assessment that is urgent, on the same day, from your GP, your rheumatology or respiratory team, or NHS 111:

• A fever, or feeling generally unwell, on immunosuppressant, biologic or steroid treatment, since an infection has to be treated early
• A persistent dry cough with a fever, with new breathlessness, or that is worsening over hours to days
• A fever with a chesty cough, or with breathlessness, whatever medicines you take, since a chest infection on scarred lungs needs treating early
• New chest pain, new palpitations, or breathlessness that is new or getting worse; palpitations happening now that do not stop, or that come with chest pain, breathlessness, feeling faint or fainting, belong to the first list; in pregnancy, breathlessness that comes on suddenly, or when you lie down, or with dizziness, is for your midwife or maternity unit straight away, as the pregnancy line below says
• A new red, painful eye, or sight that has blurred, dimmed or changed, which needs an eye casualty or urgent eye clinic the same day, as does an eye that light hurts; in pregnancy, any change in sight, blurring or flashing lights among them, is also for your midwife or maternity unit straight away, as the pregnancy line below says, since it can be a sign of pre-eclampsia
• Finding suddenly that you can walk less far, or manage less, than before
• Thoughts of ending your life or of hurting yourself, or harm you have done to yourself that is not serious, short of the line in the first list, which steroids can bring on: ask your GP to see you that day or call NHS 111, and Samaritans answer at any hour on 116 123
• A marked change in mood or behaviour, confusion, or seeing or hearing things that are not there, on steroid treatment, since prednisolone can do this, the more so the higher the dose; confusion that comes on suddenly is a 999 or A&E emergency, as the first list says, and so, after more than a few weeks on steroid tablets, or repeated courses or injections in the past year, is becoming very drowsy or confused during an illness or after an injury
• Unusual thirst or hunger, passing urine more often, or feeling sleepy or confused, on steroids, or swelling of the arms or legs, bruising or bleeding that is not normal, black or dark red stools, severe stomach pain, severe back pain, a severe upset stomach, being sick, or very bad dizziness, since each can be a steroid effect that needs checking without delay; pain in the abdomen or back that comes on suddenly and severely is a 999 or A&E emergency, as the first list says, and so, after more than a few weeks on steroid tablets, or repeated courses or injections in the past year, is vomiting that will not let your tablets stay down, or, during an illness or after an injury, becoming very drowsy or confused, or fainting; in pregnancy, bleeding that is not normal, and stomach pain that is severe, belong to the pregnancy line below
• Contact with measles, chickenpox or shingles, since these infections can be severe on steroids and a medicine to protect you may be needed
• Being near someone with measles, chickenpox or shingles, while you take a medicine that weakens the immune system, since measles and chickenpox can be dangerous when the immune system is weakened, and you can catch chickenpox from someone with shingles if you have never had chickenpox; NHS 111 can tell you what to do that day
• In pregnancy, any bleeding, stomach pain that is severe or does not go away after a rest, reduced baby movements, a severe headache or visual disturbance, sudden swelling of the face, hands, legs or feet, or breathlessness that comes on suddenly, or when you lie down, or with dizziness: contact your midwife or maternity unit straight away, whatever the time; bleeding that is heavy, or that comes with severe pain in the tummy, pain in the shoulder, or feeling sick, faint or dizzy, or passing out, is a 999 or A&E emergency: call 999 and do not drive yourself to A&E; pain in the abdomen or back that comes on suddenly and severely is a 999 or A&E emergency, as the first list says
• A high temperature in pregnancy, whatever medicines you are taking, since a fever can be a sign of an infection that needs checking; your midwife or maternity unit can advise
• In pregnancy, contact with someone who has an illness with a rash, measles, chickenpox and shingles among them, whatever medicines you are taking, since some of these infections can harm an unborn baby: ring your midwife or maternity unit, or your GP, straight away

Breathlessness or a cough that has drifted slowly from your usual, over weeks or months, is something to tell your team promptly, without waiting for a routine slot; treatment and monitoring can then be adjusted. If you take a steroid or a biologic, the warning signs that belong to each are set out in our guides to steroids and biologics and JAK inhibitors. If you cannot tell how urgent something is, asking is never a mistake.

ILD often begins quietly in the rheumatic conditions that can reach the lungs; noticed sooner, it leaves more room to protect breathing and quality of life. The best chance of keeping well comes from a rheumatologist who has the lungs in mind from the outset, sets up the right screening and works closely with respiratory colleagues. If you have a connective tissue disease and your breathing has drifted slowly from its usual, or a cough will not go, raise it promptly with your team rather than hoping it will settle; severe breathlessness, the kind that leaves you gasping, choking or unable to talk, is a 999 or A&E emergency, and breathlessness that is new or getting worse a same-day matter (in pregnancy, breathlessness that comes on suddenly, or when you lie down, or with dizziness, is for your midwife or maternity unit straight away), as the section above sets out.

Why is my rheumatologist interested in my lungs?

Because the lungs, like the joints and the skin, can be involved in several rheumatic conditions, and in systemic sclerosis and mixed connective tissue disease above all. Inflammation in a joint and inflammation of lung tissue come from the same immune process, and in the lungs it can leave scarring: that is interstitial lung disease, or pulmonary fibrosis, and it can happen without much warning. That is why a rheumatologist asks about your breathing, screens the lungs where the risk is higher and shares the follow-up with respiratory colleagues, so that any involvement is found and treated early.

Is pulmonary fibrosis just another name for interstitial lung disease?

Not quite, though they overlap. Of the two, interstitial lung disease (ILD) is the wider label, covering a large family of conditions; what they share is that the tissue separating the lungs' air sacs becomes inflamed and then scarred. The scarring itself is called pulmonary fibrosis, the name many people have heard. Pulmonary fibrosis, then, is part of ILD and not a separate condition alongside it. The label connective tissue disease-associated ILD is often used when ILD occurs with a rheumatic condition.

What tests find and follow interstitial lung disease?

Two tests matter more than any other: lung function tests, which are breathing tests that measure how well the lungs take air in and pass oxygen on, and high-resolution CT, a detailed scan that shows the pattern of any inflammation or scarring. The examination itself includes listening to the chest and a check of the oxygen level. In systemic sclerosis everyone is screened at diagnosis, with a CT scan and breathing tests. The breathing tests come round yearly after that, within the annual check for raised pressure in the blood vessels of the lungs, and once ILD has been found they are done every three to six months in the first few years, then somewhere between every six months and once a year. Everyone with mixed connective tissue disease, and those with myositis who carry a higher risk, are screened at diagnosis too, the aim being to catch any change early.

What treatment is there for interstitial lung disease?

The driver of the disease decides the treatment. When inflammation dominates, the medicines often chosen are those that hold the immune system back, mycophenolate among them. If the scarring keeps advancing regardless, nintedanib or another antifibrotic medicine may be added to slow its progress. For some people, oxygen and pulmonary rehabilitation make breathing easier and keep them active. A respiratory team is usually involved as well, and the plan is put together for you and revisited over time.

Which symptoms need urgent attention?

Breathing so difficult that you are gasping, choking or unable to get words out, a blackout, coughing up blood, chest pain that is crushing, tight or like a pressure, that spreads to an arm, the jaw, the neck, the stomach or the back, that comes with breathlessness, sweating, feeling sick or feeling light-headed, or that came on suddenly and does not go away, and the signs of sepsis, a high fever with shaking, confusion, rapid breathing, or feeling dramatically worse over hours, are 999 or A&E emergencies; the first list in the When to seek help section has the full set, the signs of a stroke among them. Call 999 and do not drive yourself to A&E. Short of those, breathlessness that is new or getting worse, or a cough or breathlessness arriving with a fever, means an assessment the same day, from your GP, your rheumatology or respiratory team, or NHS 111 (in pregnancy, breathlessness that comes on suddenly, or when you lie down, or with dizziness, is for your midwife or maternity unit straight away), because a chest infection or a flare of inflammation in the lung needs prompt attention. Your team should also hear promptly about a slow drift in your usual breathlessness or cough, over weeks or months; that is not something to save for the next routine appointment.