A range of factors may trigger an exacerbation, for example, a viral infection or smoking. Only half of exacerbations are caused by bacterial infection.

Oral corticosteroids, at a dose of 30mg for five days,⁴⁶ should be considered for people with COPD with an exacerbation causing breathlessness which is interfering with their usual day to day activities, unless they are contraindicated.

An antibiotic may sometimes be necessary for an acute exacerbation of COPD, depending on factors such as severity of symptoms, including purulence of sputum, previous exacerbations or hospital admissions and risk of complications. Five-day courses of antibiotics are recommended as this is effective, reduces risk of resistance and minimises adverse effects.

Treatment failure with antibiotics requires a sputum culture before prescribing further antibiotics. If symptoms worsen despite antibiotic therapy, other causes must be investigated, e.g. pneumonia.⁴⁸