Cystic fibrosis

Last updated:

Reviewed by:

Dr Rhianna McClymont

, Lead GP at Livi

Medically reviewed

Cystic fibrosis causes thick, sticky mucus to build up in the lungs and digestive system. It is a disease that's inherited and worsens over time. Find out more about the symptoms and what treatment is available.

What causes cystic fibrosis?

Cystic fibrosis is a genetic condition that causes significant damage to the lungs, digestive system and other organs. It makes the mucus in the body thick and sticky. In the lungs, the mucus clogs the airways, trapping germs like bacteria, which can cause infections, inflammation, and other serious complications.

The mucus can also build up in the digestive system, preventing the release of enzymes that help the body absorb food and essential nutrients. This can lead to malnutrition, difficulties putting on weight, and low growth rates in children.

Cystic fibrosis

Cystic fibrosis symptoms vary from person to person, depending on the severity of the disease. The symptoms can change over time. Some people may not experience any symptoms until their teenage years or into their adulthood.

Symptoms of cystic fibrosis:

  • Regular chest infections like bronchitis or pneumonia

  • Wheezing

  • Persistent coughing, sometimes producing mucus

  • Shortness of breath

  • Difficulty putting on weight

  • Delayed growth in children

  • Jaundice

  • Bowel problems like constipation, diarrhoea, or large 'greasy' stools (poo)

  • People with cystic fibrosis may also develop other health conditions, including:

    • Diabetes

    • Osteoporosis (weak bones)

    • Liver disease

    • Infertility in men

What causes cystic fibrosis?

Cystic fibrosis is caused by a faulty gene (it's called the cystic fibrosis transmembrane conductance regulator gene or CFTR). The gene is inherited and affects the way salt and water moves in and out of the cells in your body. People with cystic fibrosis are born with the condition – it's not something you can catch from someone else.

If you're born with cystic fibrosis, you inherit a copy of the faulty gene from both of your parents. This can happen if your parents are carriers of the CFTR gene, which means they don't have cystic fibrosis themselves.

If you inherit only one copy of the faulty gene, you won't develop cystic fibrosis. But you will be a carrier and could pass the gene on to your children.

What's the life expectancy for people with cystic fibrosis?

Cystic fibrosis is a progressive disease which means it gets worse over time. It can lead to severe infection or lung damage, which can be fatal. But people with cystic fibrosis are now living longer, thanks to advances in treatment. Currently, about half the people with the condition will live past the age of 40 years. If children are born with cystic fibrosis now, they are likely to live even longer.

Diagnosing cystic fibrosis

All newborn babies in the UK are screened for cystic fibrosis as part of the standard heel prick test carried out just after they're born.
If the test results suggest the baby may have cystic fibrosis, more tests will be done to confirm the diagnosis, including:

  • Sweat test – measuring the amount of salt in a child's sweat. If the child has cystic fibrosis, the salt level will be abnormally high.

  • Genetic test – checking for the faulty gene in a sample of blood or saliva.

These tests can also be used to diagnose cystic fibrosis in older children and adults. It's also possible to use the genetic test to check if someone is a cystic fibrosis carrier. This is important for people who want to have children and think they may have the faulty gene that causes the condition.

Treatments for cystic fibrosis

Although there's no cure for cystic fibrosis, there are various treatments to help relieve the symptoms, and prevent or reduce the risk of complications.


  • Antibiotics – to treat and prevent lung infections. They're usually in liquid or tablet form, but in severe cases, they can be delivered intravenously (through a vein).

  • Medication to thin the mucus – certain medicines can help make the mucus thinner and less sticky, allowing you to cough up the phlegm to improve your breathing.

  • Nonsteroidal anti-inflammatory drugs (NSAIDs) – medicines like ibuprofen may help improve inflammation in the airways.

  • Bronchodilators – help to widen the airways and make breathing easier.

  • Steroid medicine – to treat polyps (small growths) inside the nose.

  • Routine vaccinations – it's important that people with cystic fibrosis are up to date with all the vaccinations available, like the flu jab, to prevent illness and serious complications.

Physical therapy and equipment:

  • A physiotherapist can teach people with cystic fibrosis techniques to keep their lungs and airways clear. These include:

  • Active cycle of breathing techniques (ACBT) – a way of deep breathing, huffing, coughing and relaxed breathing to move mucus.

  • Autogenic drainage – controlled breathing techniques to clear mucus from the lungs. A standard method involves placing the head over the edge of a bed and having someone clap with cupped hands along the sides of the chest.

  • Airway clearance devices – handheld tools that use breathing techniques, vibration and air pressure to remove mucus from the airways

  • Inflatable vest – a special vest which vibrates at a high frequency to help remove mucus in the chest.


If the cystic fibrosis is very severe and all medical treatments haven't helped, doctors may recommend a lung transplant. It's a serious operation that carries risks, but it can improve the length and quality of life for people with severe cystic fibrosis.

Last updated:
Reviewed by:
Dr Rhianna McClymont, Lead GP at Livi