If an acute cough worsens rapidly or significantly over 24-48 hours, a possible alternative diagnosis is pneumonia, although the condition can also develop slowly over days. Risk groups include babies and young children, the elderly, smokers, or people with a weakened immune system or with asthma, cystic fibrosis, or heart, kidney or liver conditions.12,19

Pneumonia is a lung tissue infection, usually bacterial (typically streptococcal, and most likely Streptococcus pneumoniae), causing the air sacs in the lungs to fill with microorganisms, fluid and inflammatory cells. However, viral causes are more common in children, often due to respiratory syncytial virus (RSV) or sometimes influenza type A or B. Fungal pneumonia is uncommon in the UK, but is most likely in immunocompromised people.19,20

In addition to a cough and difficulty in breathing, symptoms can include tachycardia, fever, sweating and shivering, general malaise, appetite loss and chest pain. This gets worse on breathing in or coughing. Less common symptoms include coughing up blood (haemoptysis), headaches, fatigue, nausea or vomiting, wheezing, and aching joints and muscles. Elderly patients may become confused or disorientated.19

Each year, around 0.5 per cent to 1 per cent of adults develop pneumonia in the community, while at any one time 1.5 per cent of hospital inpatients will have hospital-acquired pneumonia (HAP).20