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What is CF?

Cystic fibrosis (CF) is a genetic condition affecting more than 10,800 people in the UK. You are born with cystic fibrosis and cannot catch it later in life, but one in 25 of us carries the faulty gene that causes it, usually without even knowing. Find out more...

The gene affected by CF controls the movement of salt and water in and out of cells. People with cystic fibrosis experience a build-up of thick sticky mucus in the lungs, digestive system and other organs, causing a wide range of challenging symptoms affecting the entire body. Read on for more details and links to relevant information, or examine our new interactive body!


To have CF,  you need to have inherited two faulty copies of the gene (one from each parent), and as there are many different gene mutations that cause cystic fibrosis, each person with the condition can have very different symptoms depending on the two genes they carry. While people with CF often look healthy on the outside, each individual is battling their own range of symptoms on a daily basis. Find out more about genetics and diagnosis.

The lungs

The build-up of mucus in the lungs causes chronic infections, meaning that people with cystic fibrosis struggle with reduced lung function and have to spend hours doing physiotherapy and taking nebulised treatments each day. Exacerbations (a sudden worsening of health, often owing to infection) can lead to frequent hospitalisation for weeks at a time, interfering with work and home life. Find out more about how the lungs are affected and some of the research we’re funding to help.

The digestive system

As the pancreas becomes blocked with mucus, enzymes required for digesting food cannot reach the stomach. People with cystic fibrosis often need to take more than 50 tablets a day to help digest food and keep respiratory symptoms in check. Find out more about how CF affects the digestive system.

Cystic fibrosis is... what, exactly?

Charles breaks it down in this useful video:


The mucus in the lungs of people with cystic fibrosis contributes to a range of issues, making it hard to breath and increasing the risk of infection.

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Digestive system

People with cystic fibrosis struggle to digest food properly, often requiring enzymes at mealtimes to help them.

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One of the most striking features of cystic fibrosis is cross-infection – the risk that people with cystic fibrosis pose to each other. Two people with the condition should never meet face-to-face, as their lungs will harbour specific bugs/infections that could cause a serious infection in someone else with the condition. This means no support groups, and requires strict segregation to be in place at CF clinics.

How is it diagnosed?

Find out all about diagnosis (newborn or later in life) and what support and resources are available to help you make sense of it all.

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Heel prick test on baby

Are you a carrier?

Read about tests to see if you're one of the 1 in 25 people in the UK who carry a cystic fibrosis gene, and what it could mean for you.

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What causes CF?

Mutations, alleles and DNA - talking about genetics can be confusing! Discover more about the cause of cystic fibrosis and what it all means.

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Scientist cutting DNA model

Other complications

Men with cystic fibrosis are usually infertile, and pregnancy can place a lot of stress on the body of a woman with cystic fibrosis. Our resource on fertility and pregnancy explains this in more detail. Other complications can include CF-related diabetes, bone disease and bowel obstruction. 

Take a look at our Frequently Asked Questions to find out more, or get in touch with our helpline.


Find out more about cystic fibrosis, including stories from inspiring individuals living with the condition in our 'is' magazine and helpful factsheets on a wide range of associated medical and social issues.

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Check out the most commonly asked questions about cystic fibrosis.

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The big picture

Understanding and treatment of cystic fibrosis have come so far since the condition was first described in the 1930s. More than half of people with cystic fibrosis in the UK will now live past 47, and babies born today are expected to surpass that. With more than 50% of the CF population in work or education and many people with cystic fibrosis having families of their own, you can see evidence of a brighter future wherever you turn. Part of this is down to the increasingly personalised healthcare available for people with cystic fibrosis. We are fighting to lift all of the limits that cystic fibrosis places on people with the condition, so that they can live long and healthy lives.

Find out more about the UK CF Registry, a unique database of consenting patients’ data, and the research we are funding into cystic fibrosis. If you want to be a part of our fight, we’d love you to join Team CF and fundraise for us – or make a donation to ensure we can continue our work.


Find out more about the treatments and medications to help manage the symptoms of cystic fibrosis.

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Related conditions

Cystic fibrosis can cause related conditions such as CF-related diabetes or osteoporosis. Find out more about what to look out for and the treatments available to manage these conditions. 

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