Asthma vs COPD: how the two airway conditions differ

Asthma is a condition of sensitive, inflamed airways that narrow in response to triggers. The narrowing varies from day to day and often improves with treatment. COPD is damage to the airways and air sacs that builds up over many years, usually from smoking, and leaves a degree of persistent airflow limitation that does not fully reverse. In asthma the story is typically of episodes, in childhood or young adulthood, with trigger patterns and an allergic background. In COPD it is typically a smoker or ex-smoker in their fifties or later with progressive breathlessness, a chesty cough with phlegm and frequent chest infections.

The lines are not always clean. The NHS says asthma can start at any age and that COPD can sometimes affect people who have never smoked, and both can cause wheeze and breathlessness. That is why a diagnosis rests on history, a breathing test and a clinician's judgement rather than on symptoms alone.

The NHS says the main symptoms of asthma are wheezing, coughing, shortness of breath and a tight chest. They can be mild or severe, usually come and go, and may be worse at night and early in the morning. Triggers include exercise, high levels of air pollution, cold air and contact with allergens such as pollen, dust, mould or animals. An asthma attack is when symptoms are severe and it is difficult to breathe, which can be life-threatening.

Asthma + Lung UK says asthma is a long-term condition in which airways become swollen and narrow, that 7.2 million people in the UK have it, and that for most people it is lifelong, though most can control symptoms well with inhalers. The NHS says you may be more likely to get asthma if you have allergies such as eczema or hay fever, a family history, were born prematurely, or were exposed to air pollution or cigarette smoke as a child. Treatment is mainly inhalers: a reliever for symptoms and a preventer to reduce inflammation, or a combined AIR or MART inhaler, supported by an asthma action plan and an annual review.

The NHS describes COPD as the name for a group of lung conditions that cause breathing difficulties, including emphysema and chronic bronchitis. It is a common condition that mainly affects middle-aged or older adults who smoke, and many people do not realise they have it. The main symptoms are shortness of breath, particularly when active, a persistent chesty cough with phlegm that some people dismiss as a smoker's cough, frequent chest infections and persistent wheezing. Without treatment the symptoms usually get progressively worse, with periods when they get suddenly worse, known as flare-ups, which are common, particularly in winter.

The NHS says COPD happens when the lungs become inflamed, damaged and narrowed, and that smoking is the main cause. The damage is permanent, but treatment can help slow the condition. The most important thing a person who smokes can do is stop. Other treatments include inhalers and medicines, pulmonary rehabilitation, and surgery or lung transplant for a very small number of people. Asthma + Lung UK describes COPD as a progressive condition that gets worse over time.

For COPD, the NHS says a GP asks about symptoms and smoking, examines the chest and may arrange spirometry, a breathing test in which you breathe into a machine after inhaling a bronchodilator, with results compared with normal values for your age to show whether airways are obstructed. A chest X-ray and blood tests look for other causes, and further tests such as a peak flow test, which can help rule out asthma, may be used.

For asthma, the NHS says a GP or nurse asks questions and listens to the chest, may arrange a simple breathing test and sometimes a blood test, and may give you a peak flow meter to use at home for a few weeks. It also says asthma can take time to diagnose because symptoms vary and breathing problems can have different causes, and that if asthma is likely you may be offered asthma medicines to see if they help.

The NHS advises seeing a GP if you or your child have asthma symptoms, or if treatment is not helping or you are needing your inhaler more often. For COPD it advises seeing a GP for persistent symptoms, particularly if you are over 35 and smoke or used to smoke, and not ignoring them, because starting treatment early is best. In an asthma attack the NHS advises sitting up, using your reliever inhaler as directed and calling 999 if you feel worse or do not feel better after the maximum dose.