Legionnaires' disease

Also called Legionellosis or Legionella pneumonia

Legionnaires' disease is a serious type of pneumonia caused by Legionella bacteria. It is caught by breathing in tiny droplets of water containing the bacteria, for example from air conditioning systems, hot tubs, showers or water tanks in large buildings. It does not usually spread from person to person.

Last updated Nov 9, 2026

What it is

It is more likely in people over 50, smokers and people with weak immune systems or long-term illnesses.

It is treated with antibiotics, usually in hospital. Most people recover, but it can be serious.

Common signs

  • High temperature and chills
  • Cough
  • Shortness of breath
  • Chest pain
  • Muscle aches, headache and confusion

How it is usually diagnosed

  • Urine test for Legionella
  • Chest X-ray
  • Blood tests and sputum samples

Records worth keeping

Keeping these together makes each appointment easier, especially when you see a new doctor:

  • Test results
  • Chest X-ray reports
  • Hospital discharge letters

Questions to ask your doctor

  • Where might I have caught it?
  • How long will recovery take?
  • Do I need a follow-up X-ray?

When to get help right away

Call 112 or go to the nearest emergency department if you have:

  • Difficulty breathing, chest pain, confusion or blue lips: call 112

This page is general information. It is not a diagnosis and does not replace a doctor who knows your history. Medfold keeps your records organised; it does not interpret them.

Sources