Chronic obstructive pulmonary disease, usually shortened to COPD, is a long-term lung condition in which the airways become narrowed and inflamed and the lungs are damaged, so air moves in and out less easily and breathing becomes harder over time [1,3].
This page provides general information. It does not replace advice from a doctor or another qualified healthcare professional.
The name explains itself. Chronic means long-term. Obstructive means the airways are narrowed. Pulmonary means it affects the lungs [10]. The lining of the airways swells, the walls between the tiny air sacs can be destroyed, and the airways make more mucus [8]. Air gets trapped in the chest, and breathing out takes effort [1].
The old split into two diseases has largely gone. COPD was long described as two conditions: emphysema, meaning damage to the air sacs, and chronic bronchitis, meaning a long-term cough that brings up phlegm. Those words still describe real changes, and some health services still say COPD “includes” them [6,19]. Current guidance treats chronic bronchitis as a common but variable feature of COPD, present in roughly 27% to 35% of people who have it, rather than a separate disease [1]. Most people have a mixture, so describing COPD as “two main conditions”, as the page this replaces does, is out of date.
COPD is not asthma, though they share symptoms and some people have both. In asthma the narrowing comes and goes; in COPD it is largely permanent [10].
Two very different sets of numbers exist. Studies that measure breathing give the higher figure: a review across 65 countries estimated that 10.3% of people aged 30 to 79 had COPD in 2019, about 392 million people, roughly 315 million in low- and middle-income countries [1].
Counts of people told they have it are far lower. Fewer than 6% of adults report a diagnosis in most national surveys, and one analysis estimated that 81% of cases found by breathing tests were undiagnosed [1]. National figures follow the same pattern: 11.7 million diagnosed in the United States with perhaps 18 million more unaware [9], about 1.7 million in the United Kingdom with roughly 600,000 undiagnosed [10], and almost half of affected Australians over 40 unaware [15].
COPD is the third leading cause of death worldwide, linked to about 3.4 million deaths in 2023, and nearly 90% of deaths from it under age 70 happen in low- and middle-income countries [3].
COPD builds up over years, from breathing in things that damage the lungs, and from how a person’s lungs grew and aged [1].
Smoking is the largest single cause: more than 70% of cases in high-income countries, and 30% to 40% in low- and middle-income countries [3]. Around 9 in 10 United Kingdom cases are linked to it [4,10]. The link is also incomplete: fewer than half of heavy smokers develop COPD, and about half of all cases worldwide are due to causes other than tobacco [1]. A substantial number of people with COPD have never smoked, and nobody with the condition should be treated as having brought it on themselves.
Air pollution indoors matters greatly elsewhere. Wood, animal dung, crop residue and coal are burned for cooking and heating in poorly ventilated rooms, and in the lowest-income countries this is the leading risk factor for death from COPD [1,3]. Dust and fumes at work account for around 2 in 10 United Kingdom cases, and poor growth before birth, severe childhood chest infections and childhood asthma can all stop the lungs reaching full size [3,4,10].
An inherited cause. A gene is a set of instructions inside cells, a gene variant is a change in those instructions, and inherited means passed from parent to child. Changes in a gene called SERPINA1 cause alpha-1 antitrypsin deficiency, in which the body makes too little of a protein that protects the lungs. People with it often develop COPD younger, especially if they smoke, and guidance recommends testing everyone diagnosed with COPD for it [1,4]. See our guide to alpha-1 antitrypsin deficiency.
Symptoms come on slowly, usually from mid-life, and are easy to put down to age or poor fitness [3]. The common ones are [3,7,10]:
Flare-ups. Symptoms can worsen sharply over a few days: more breathlessness, more coughing, or phlegm that changes color. This is a flare-up, or an exacerbation [1,11]. Flare-ups usually last seven to ten days, about 1 in 5 people still have symptoms eight weeks later, and they can cause lasting lung damage [11].
When to seek urgent help. Call emergency services, 999 in the United Kingdom or 911 in the United States, if you are finding it very hard to breathe and are gasping, choking or cannot speak, if your chest feels tight or heavy, if pain spreads to your arms, back, neck or jaw, if your lips or skin turn very pale or blue, or if you suddenly become confused [11]. For milder worsening, follow your agreed plan and contact your team the same day.
A family doctor usually starts, asking about symptoms, listening to the chest, and asking about smoking and family history. Guidance in England says to suspect COPD in anyone over 35 who has a risk factor and any of the symptoms above [5,7].
Spirometry confirms it. You breathe into a machine after taking a medicine that opens the airways. It records how much air you can blow out in the first second and how much in total. If the first-second amount is less than 70% of the total, the airways are obstructed [1,5,7]. A chest X-ray, blood tests and sometimes a CT scan rule out other explanations [5,7].
Why it is often missed, and sometimes got wrong. Being missed is linked with being younger, being male, never having smoked and never having had a breathing test, and many quietly do less rather than mention breathlessness [1,8]. The 70% cut-off is also imperfect: it can label some older people as having COPD when they do not, and miss it in younger people, so guidance in England asks doctors to weigh symptoms alongside the number [1,7]. Women have long been misdiagnosed more often, since COPD was thought of as a man’s condition [8].
There is no cure. Treatment eases symptoms, reduces flare-ups, slows decline, and many people live well for years [3,15].
Stopping smoking is the only step that changes the course of the condition. Current guidance states plainly that it has the greatest capacity to influence how COPD progresses, and it also improves symptoms and reduces flare-ups [1]. It is never too late, and counseling with medicine works better than either alone [1,6].
Inhalers, added in steps. Short-acting relievers such as salbutamol come first, used when breathless. Long-acting inhalers are added when symptoms are regular or flare-ups happen: a long-acting antimuscarinic, or LAMA, such as tiotropium, plus a long-acting beta-2 agonist, or LABA, such as salmeterol. Guidance recommends starting both together for most people with troublesome symptoms. Triple therapy adds an inhaled steroid for those who keep having flare-ups, guided by a blood test counting a white cell called an eosinophil [1,6,7]. Technique is checked regularly, since the medicine only works if it reaches the lungs [1,7].
Pulmonary rehabilitation is strongly evidenced and often not offered. It combines supervised exercise with education, usually over six to eight weeks, and improves exercise capacity, symptoms and quality of life at every severity [1,6]. Referral is uneven: older people, women, people in deprived areas and those with other conditions are less likely to be referred [1].
Vaccination, flare-ups and oxygen. An annual flu vaccine, a pneumococcal vaccine and COVID-19 vaccination are recommended for everyone with COPD [1,7,9]. Flare-ups are treated with a reliever inhaler, steroid tablets and antibiotics where there are signs of infection, with hospital care for severe ones [6,11]. Oxygen at home is used only where the blood oxygen level is low while the condition is stable [1,6].
Newer options, with honest notes on availability. Ensifentrine, sold as Ohtuvayre, is a nebulized medicine that both opens the airways and reduces inflammation. It was approved in the United States in June 2024, and current global guidance states that it is available only there [1,12]. Dupilumab, approved in the United States in September 2024 after approvals in the European Union and China [13], and mepolizumab, approved there in May 2025 [14], are biologic medicines for adults whose COPD is inadequately controlled and who have raised eosinophils. Both were recommended in England during 2026 [7]. Availability elsewhere differs, and none is a first-line treatment. Access is unequal beyond medicines too: spirometry itself is often unavailable in low- and middle-income countries [3].
Care is usually shared between a family doctor, a practice nurse and, where needed, a lung specialist team, with an annual review of symptoms, inhaler technique and vaccinations [7]. A written self-management plan is worth asking for, setting out what a flare-up looks like and who to contact [11].
Staying active helps, and avoiding tobacco smoke, cooking smoke indoors and high-pollution days reduces flare-ups [3]. Other conditions are more common in people with COPD, including heart problems, lung cancer, thinner bones, depression and anxiety, and around 1 in 5 also have asthma [3,15].
Clinical trials test whether a treatment works and is safe. COPD research is active, particularly in preventing flare-ups. Deciding whether to look into a study is personal, and it helps to take it in steps.
Worth being clear on what a study involves:
Every trial has rules about who can take part, called eligibility criteria. For a COPD study they might include a diagnosis confirmed by spirometry, a breathing measurement inside a set range, a set number of flare-ups in the past year, a stable dose of existing inhalers beforehand, and a particular eosinophil count on a blood test.
trialport’s medifit helps people consider information related to possible medical suitability. It does not diagnose a condition, confirm eligibility or replace formal screening by the study team.
Explore COPD clinical trials through trialport
A study can look right on paper and still be hard in practice:
trialport’s readifit helps people reflect on their understanding, motivation, time, routines, support, emotions and practical arrangements.
Useful questions to put to a research team:
Taking part is voluntary. A person can ask questions, speak with people they trust and choose not to participate.
Search for clinical trials at app.trialport.com.
Study status checked: 3 August 2026. Research moves quickly, and what is being studied changes, so this list will date. For current information, search at app.trialport.com.
Coverage varies by country. Many places have a general lung charity rather than a COPD organization, and the treating clinic is then the best route.
The actor Leonard Nimoy, who played Spock in Star Trek, announced in 2014 that he had been diagnosed with COPD, roughly 30 years after he stopped smoking. He urged people to quit, writing “I have COPD. Grandpa says, quit now!!!” [18]. He died in 2015, and the American Lung Association later worked with his daughter’s foundation to raise awareness and reduce stigma [9].
Is COPD the same as emphysema or chronic bronchitis?
Not quite. Those words describe changes that happen in COPD, and current guidance treats them as features rather than separate diseases [1].
Can you get COPD if you have never smoked?
Yes. About half of cases worldwide are due to causes other than tobacco, including cooking and heating smoke indoors, dust and fumes at work, poor lung growth in early life, and an inherited protein deficiency [1,3].
Can COPD be cured?
No. Treatment eases symptoms and reduces flare-ups, and stopping smoking does most to slow it [1,3].
Do I definitely need a breathing test?
Yes. Spirometry is required to confirm COPD, since symptoms alone cannot separate it from asthma or heart problems [1,7].
Should I avoid exercise if I get breathless?
No. Supervised exercise through pulmonary rehabilitation improves exercise capacity, symptoms and quality of life [1].
Written by: trialport editorial team
Reviewed by: Keith Berelowitz, Founder and CEO, trialport
Reviewed on: 3 August 2026
Next review due: 3 August 2027
References last checked: 3 August 2026