Community acquired pneumonia - Diagnosing pneumonia

Your GP can often diagnose pneumonia by asking questions about your symptoms and examining your chest. In some cases, further tests may be needed.

Pneumonia can sometimes be difficult to diagnose, as it shares many symptoms with other conditions, such as the common cold, bronchitis and asthma.

To make a diagnosis, your doctor may first ask:

• if you are breathing faster than usual
• if you feel breathless
• how long you have had your cough
• whether you are coughing up sputum and what colour it is
• if the pain in your chest is worse when you breathe in or out

Your doctor will probably take your temperature and listen to the back and front of your chest with a stethoscope, to check for any crackling or rattling sounds.

They may also listen to your chest by tapping it. Lungs filled with fluid produce a different sound to normal, healthy lungs.

Most people with mild pneumonia do not need to have a chest X-ray or any other tests.

Chest X-ray and other tests

Your GP may arrange a chest X-ray or other tests if your symptoms have not started to improve within 48 hours of starting treatment.

A chest X-ray can show how much your lungs are affected. It can also help the doctor distinguish between pneumonia and other chest infections, such as bronchitis.

Your GP may also arrange:

• a sputum test
• blood tests 

Analysing samples of sputum or blood can help identify the bacterium or virus causing the infection.

Screening for lung cancer

Although uncommon, pneumonia can sometimes be a symptom of underlying lung cancer in people who smoke and are 50 years of age or over.

If you fall into one of these groups, your GP may refer you for a chest X-ray.

If your X-ray does not detect cancer, a follow-up X-ray is recommended six weeks later. This is a way of "double-checking" that all is well with your lungs.