Legionnaires’ disease

Legionnaires’ disease is an uncommon but potentially serious form of pneumonia. Often an outbreak involves hundreds of people coming into contact with the same source, but sometimes only one person gets the disease.

On this page we will answer:


How do you get Legionnaires’ disease?

You get infected if you breathe in droplets of water from a contaminated water source such as:

  • air conditioning systems
  • spa pools and hot tubs
  • showers and taps
  • cooling towers
  • decorative fountains

It is very unlikely that you catch Legionnaires’ disease from:

  • ponds, lakes and rivers
  • drinking water with the bacteria in it
  • other people with the infection

About 3 in 10 cases of Legionnaires’ disease are contracted abroad, so always mention any recent foreign travel when you see your doctor and you’re unwell.


How can Legionnaires’ disease be prevented?

Good maintenance and regular flushing of water systems are key to prevention.

Employers and landlords have a legal duty to make sure all water systems in their premises are properly maintained. Regulations and guidance are issued by the Health & Safety Executive UK. If you have concerns about air conditioning or water systems at work, you could ask your office manager (or your health and safety rep or your union rep, if you have one) if the systems are checked regularly.

You can also reduce the risk of Legionnaires’ disease at home by removing any build-up around shower heads as this can trap water. And, if you have taps you don’t use, flush them by opening the tap and letting the water run for 5 minutes every fortnight.

If you have a home spa or hot tub, it’s essential to regularly drain, clean and disinfect it.  Follow the manufacturer’s instructions and it’s important to buy and use the recommended products.


Who is at risk of Legionnaires’ disease?

Anyone can develop Legionnaires’ disease. But you’re more likely to get it if you’re older and:

  • you have a long-term lung condition like asthma or chronic obstructive pulmonary disease (COPD)
  • you have a long-term condition that affects your heart, your kidneys or other major organs
  • you smoke
  • you are dependent on alcohol or drugs
  • you have problems with your immune system

What are the symptoms of Legionnaires’ disease?

If you have Legionnaires’ disease, you’ll have symptoms similar to pneumonia, flu or a chest infection.

These symptoms can include:

  • coughing
  • a high temperature
  • difficulty breathing
  • chest pain or discomfort

If you have the following severe symptoms, get urgent advice from your GP or 111:

  • high temperature and fever
  • you feel like you have severe flu
  • you have severe chest pain and can’t breathe properly

More severe cases of Legionnaires’ disease may also cause:

  • feeling and being sick
  • diarrhoea
  • confusion

The period of time between breathing in the bacteria and developing symptoms is normally between 2 – 10 days. However, it can take up to 2 weeks. Symptoms tend to develop quickly as the infection spreads across your lungs.


How is Legionnaires’ disease treated?

If you have Legionnaires’ disease, the sooner you get treatment, the better:

  • you may be given antibiotics directly in a vein.
  • you may be given oxygen.
  • if you have a severe case, you may be looked after in intensive care and have a machine to help you breathe.

When you start to feel better, you may need to continue to take antibiotic tablets at home. Antibiotic treatment usually lasts 1 to 3 weeks. You’re likely to make a full recovery and feel back to normal after a few weeks.

If you have concerns or need advice, call our helpline on 03000 030 555 between 9am and 5pm on a weekday or email them.

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Download our Legionnaires' disease information (PDF, 128KB)

Last medically reviewed: October 2019. Due for review: September 2022

This information uses the best available medical evidence and was produced with the support of people living with lung conditions. Find out how we produce our information. If you’d like to see our references get in touch.