Cystic fibrosis


Cystic fibrosis


Cystic fibrosis is a genetic condition in which the lungs and digestive system become clogged with thick sticky mucus.

Symptoms usually start in early childhood and include:

persistent cough

recurring chest and lung infections

poor weight gain

An early sign is that an affected child’s sweat is unusually salty, which can be noticeable when you kiss your child. 

However, most cases of cystic fibrosis in the UK are now identified through screening tests carried out early in life, before symptoms appear.


Treating cystic fibrosis

As there is no cure for cystic fibrosis the aim of treatment is to ease symptoms and make the condition easier to live with. For some rare types of cystic fibrosis, such as the G551D mutation, there are treatments which aim to compensate for a defective gene.

Treatment can also prevent or reduce long-term damage caused by infections and other complications.

Treatment options include:

antibiotics – to treat chest and lung infections

physiotherapy – a range of exercises can help clear mucus from the lungs

bronchodilators – a type of medication that helps expand the airways inside the lungs, making it easier to breathe

inhaled mucus-clearing treatments – such as pulmozyme, hypertonic saline (a strong salt solution) and mannitol dry powder

In some cases a lung transplant may eventually be required if the lungs become extensively damaged.


What causes cystic fibrosis?

Cystic fibrosis is caused by a genetic mutation; specifically a mutation in a gene called CFTR. A genetic mutation is when the instructions found in all living cells become scrambled in some way, meaning that one or more of the processes of the body do not work in the way they should.

The CFTR gene normally creates a protein that regulates levels of sodium and chloride in cells. If the CFTR gene is defective, it results in a build-up of thick, sticky mucus in the body's tubes and passageways. These blockages damage the lungs, digestive system and other organs, resulting in the symptoms of cystic fibrosis.


Who is affected

Cystic fibrosis is most common in white people of northern European descent.

It is estimated that one in every 2,500 babies born in the UK will be born with cystic fibrosis and there are more than 9,000 people living with the condition in this country.

The condition is much less common in other ethnic groups.



Babies are screened for cystic fibrosis at birth as part of the  newborn screening programme.

A small amount of the baby's blood is taken by a heel prick and transferred onto a card. The blood sample on the card is then analysed in the laboratory for cystic fibrosis and four other inherited conditions, including sickle cell anaemia.



In the past, most children with cystic fibrosis would die of related complications before reaching adulthood.

The outlook has improved considerably in recent years due to advancements in treatment, although most people with cystic fibrosis will have a shorter than average life expectancy.

It is now estimated that, on average, children born in the 21st century with cystic fibrosis will live for more than 50 years.

Causes of cystic fibrosis 

Cystic fibrosis is a genetic condition caused by a faulty gene (known as the CFTR gene). The CFTR gene normally creates a protein that moves salt and water out of a cell.

If the CFTR gene is defective, it results in a build-up of thick, sticky mucus in the body's tubes and passageways. These blockages damage the lungs, digestive system and other organs, resulting in inflammation (swelling) and, in the lungs, repeated infections.

How the CFTR mutation is passed through families

Genes come in pairs. You inherit one set of genes from your mother and one set from your father.

To develop cystic fibrosis you would have to inherit the faulty gene from both your mother and your father.

In the UK, it is thought that one person in every 25 carries the faulty gene for cystic fibrosis, which is why it is a relatively common genetic condition. A carrier is usually completely healthy and has no symptoms of cystic fibrosis.

If two carriers of the faulty gene have a baby, there is:

a one-in-four chance that the child will not inherit either of the faulty genes (the child will not have cystic fibrosis and will not be a carrier of the condition)

a one-in-two chance that the child will inherit one copy of the faulty gene from either their father or mother (the child will not have cystic fibrosis but will be a carrier of the condition)

a one-in-four chance that the child will inherit both copies of the faulty gene (the child will have cystic fibrosis)

Diagnosing cystic fibrosis 

Most cases of cystic fibrosis in the UK are now identified through screening tests carried out early in life.

However, some babies, children and even young adults are identified later following unexplained illness.


Diagnosing cystic fibrosis

There are three main ways of diagnosing cystic fibrosis:

newborn testing

antenatal testing

sweat testing

Newborn screening

Babies are offered screening for cystic fibrosis at birth as part of the  newborn screening programme.

A small amount of the baby's blood is taken by a heel prick and transferred onto a card. The blood sample on the card is then analysed in the laboratory for cystic fibrosis and four other inherited conditions, including sickle cell anaemia.

If your baby is thought to have cystic fibrosis, you will usually be contacted before the baby is four weeks old.

The sooner cystic fibrosis is diagnosed, the sooner treatment can begin and the better the outlook.

For more information on the newborn screening programme, visit UK Newborn Screening Programme Centre.


Antenatal testing

A test can be done on a woman when she is pregnant to see if her unborn baby has cystic fibrosis. This can be carried out from 10 weeks of pregnancy.

The test uses chorionic villus sampling (CVS), where a fine needle is passed through the abdomen into the womb. Sometimes, a fine tube is passed through the vagina into the cervix (neck of the womb) instead. A tiny piece of the developing placenta, known as the chorionic tissue, is taken and the chromosomes in the cells of the tissue are examined for the faulty gene that causes cystic fibrosis.

Antenatal testing for cystic fibrosis is usually only offered to mothers who are thought to be at high risk of having a child with the disease, such as women with a family history of the condition. The tests need to be discussed on an individual basis with a genetic counsellor.


Sweat test

If someone has cystic fibrosis, their sweat will have higher levels of salt than normal. A parent may first notice their child's symptoms of cystic fibrosis when they kiss them, as their skin can taste salty.

A sweat test measures the amount of salt in sweat. It is usually done by applying a very weak and painless electric current to a small area of skin to which a harmless chemical has been applied. This causes that area of skin to sweat. A sample of the sweat is then collected and analysed. If the salt content in the sweat is abnormally high, this confirms cystic fibrosis.

A sweat test may be carried out if:

newborn screening tests are abnormal

a child is born with a serious bowel obstruction known as meconium ileus

a child or adult has symptoms suggestive of cystic fibrosis

Genetic testing

A genetic test checks for the faulty cystic fibrosis gene by analysing either a blood sample or a saliva sample taken from inside the cheek using a swab. It can be useful to confirm cystic fibrosis if a sweat test gives a borderline result.

It can also be useful to find out which members of a family are carriers of the cystic fibrosis gene.


Carrier testing

There is a simple test that uses a mouthwash to identify whether a person is a carrier of the cystic fibrosis gene.

Swishing the mouthwash collects a sample of cells from the mouth. This sample is then sent to a laboratory and the cells it contains are checked for the faulty cystic fibrosis gene. The results will be discussed on an individual bases with a genetic counsellor, as the results may be misleading in some cases.

It is important to have this test if the person’s partner is a known carrier, or if someone in the family has cystic fibrosis or knows that they carry it.

Testing in later life

Older children and adults with cystic fibrosis require regular testing to check how well (or not) their lungs and digestive system are working.

Tests that can be used for this purpose are described below.



You will be asked to breathe into a machine called a spirometer.

The spirometer takes two measurements: the volume of air you can breathe out in one second (called the forced expiratory volume in one second or FEV1) and the total amount of air you breathe out (called the forced vital capacity or FVC).

You may be asked to do this a few times to get a consistent reading.

The readings are compared with normal measurements for your age, which can show if your airways are obstructed.


Chest X-rays

A chest X-ray can be a useful method for assessing the state of your lungs

Computerised tomography (CT) scan

In a CT scan, a series of X-rays are taken. These are then assembled by a computer into a more detailed ‘3D’ image of your lungs and digestive system. 


Help after diagnosis

If you or your child is diagnosed with cystic fibrosis, it can be extremely difficult to deal with.

It can help to find out as much as you can about the condition. 


Treating cystic fibrosis 

People with cystic fibrosis should be treated with help and advice from a team of healthcare professionals at a cystic fibrosis centre. With regular visits, the patient or parent can learn how to best manage the condition. As each case is different, they can receive tailored care for their or their child's condition.

There is no cure for cystic fibrosis. The aim of treatment is to ease the symptoms and make the condition easier to live with. It can also prevent or reduce long-term damage caused by infections and other complications.

Different types of treatment for cystic fibrosis are detailed below.



Medical treatments for cystic fibrosis help clear and control infections in the lungs and digestive system. They can also be used to treat some of the other health problems related to cystic fibrosis.


Antibiotics are taken to fight infections in the lungs. They can be:

taken by mouth as pills, capsules or liquids

inhaled through either a nebuliser (a device that turns medication into a mist that can be breathed in) or a more portable device that uses dry powder

given intravenously (through a tube into a vein) if the infection is more severe

In the UK, current advice is that all young children diagnosed with cystic fibrosis will be started on a course of antibiotics to protect them from certain bacteria, which will be continued for some years. For more advice on the use of antibiotics, see the Cystic Fibrosis Trust information on medication.



Pulmozyme (DNase) is an enzyme, usually inhaled via a nebuliser, which helps to thin and break down the sticky mucus in the lungs so it is easier to cough up.

In most cases DNase will not cause any noticeable side effects.


Hypertonic saline

Hypertonic saline is a strong salt solution, usually inhaled via a nebuliser, which may be used as an alternative if DNase is not effective.

It also helps to thin mucus, making it easier to cough up.


Mannitol dry powder

Mannitol dry powder for inhalation is an alternative treatment for adults with cystic fibrosis if:

you cannot use DNase or a similar medication

your lung function is getting worse

When mannitol is inhaled, it causes water to mix with mucus in the lungs. This makes the mucus less thick and sticky and easier to cough up.


People who have diabetes as a result of their cystic fibrosis will need to take insulin and manage their diet to stabilise blood sugar levels. The dietary advice usually given to people with diabetes who do not have cystic fibrosis does not apply to most people with cystic fibrosis-related diabetes.



Bisphosphonates can be taken to treat weak and brittle bones, which can occur as a result of cystic fibrosis. Bisphosphonates help maintain bone density and reduce risk of fractures.



In rare cases, steroid medication (corticosteroids) may be used to reduce the swelling of the airways, which can help with breathing in some patients. Steroid nasal drops and sprays can also be used to treat nasal polyps (small growths inside the nostrils).



Bronchodilators are a type of inhaled medication that may be used in rare cases to help a person breathe more easily. They are also used for asthma and relax the muscles that surround the airways in your lungs, helping them to open up.

Vaccinations and flu jabs

It is particularly important that people with cystic fibrosis are up to date with all the required vaccinations. People with cystic fibrosis should make sure they have an annual flu jab, as they are more susceptible to complications as a result of infection.


 Digestive system, diet and nutrition 

For people with cystic fibrosis, getting the right nutrition is vital. A healthy body weight is necessary to help fight off infections, and it is important there is enough reserve energy to rely on when the person is ill.

Cystic fibrosis causes mucus to build up and block the small channels that carry digestive juices and enzymes. Over time, this causes the pancreas to become damaged. The effect of cystic fibrosis on the pancreas varies from person to person, but most people have to take digestive enzymes from birth to help them digest food and get the nutrients they need, with every meal and snack. They also need to take vitamin supplements.

The diet of someone with cystic fibrosis should be:

high in calories – as they will not be able to digest all the food they eat

rich in fat and protein – as without all the digestive enzymes, a lot of these nutrients are lost in stools

A special diet should start as soon as cystic fibrosis is diagnosed, which will need to be adapted as people get older.


Babies with cystic fibrosis

Babies with cystic fibrosis may be breastfed as usual, otherwise most baby milks and formulas will be suitable. In some cases, if the baby is not gaining enough weight, a high-energy formula may be needed or nutritional supplements added to milk feeds to give the baby more calories (energy).

Ask a dietitian at the cystic fibrosis centre if you are unsure or read the Cystic Fibrosis Trust factsheet on feeding infants (PDF, 333kb).

Before a baby moves onto solid foods, they may need extra salt as both breast milk and baby milk are very low in salt. Cystic fibrosis makes sweat much saltier and more salt than normal is lost through skin.

If the baby needs extra salt, the dietitian or doctor at the cystic fibrosis centre will advise on the appropriate amount and prescribe a salt solution.

Never add salt to a baby's food or drink without specific advice from cystic fibrosis specialists.

Babies can eat any normal solid baby foods, but they will need vitamin supplements to compensate for the loss of vitamins A, D, E and K in their stools.

These are available in two liquid preparations. Vitamins A and D are usually combined in one, and there is usually a separate one for vitamin E. Vitamin K is now prescribed by many doctors to older children.

Most babies with cystic fibrosis will also need pancreatic enzymes to help them digest food. These take the place of the food-digesting enzymes missing from their digestive system. They usually come in the form of microspheres  (granules), which can be mixed with a little formula, expressed breast milk or fruit puree and spoon fed ideally at the start, and sometimes during, the feed.

The granules should never be given dry as they can be a choking hazard. A dietitian can advise on the amount to use and the most suitable way to give the enzymes.


Children with cystic fibrosis

Children who have cystic fibrosis should eat a varied diet, with a large amount of protein and calories. Meals should include meat, fish and eggs, as well as starchy foods like bread and pasta. If a child's appetite is poor, give them food little and often, and offer snacks in between meals.

Children who find it particularly hard to gain weight can be given dietary supplements in the form of milk shakes or fruit juices. You can talk to a cystic fibrosis dietitian about these.

Like babies, children with cystic fibrosis will need to continue taking vitamin A, D, E and K supplements to compensate for the vitamins they lose.

Most children also need to continue taking pancreatic enzymes with all fat-containing meals, snacks and drinks. The capsules should be taken before and during the meal and the number of capsules will vary depending on the fat content of the meal. Enzymes can be taken in capsules.

A dietitian may recommend salt supplements for a child with cystic fibrosis, especially in hot weather or if they are going on holiday to a country with a warm climate, where sweating may cause a loss of salt.

Children with cystic fibrosis are likely to eat more sugary foods than normal due to their high-calorie diet, so it is important to make sure they brush their teeth properly and visit the dentist regularly. 

If a child cannot gain enough weight and dietary supplements have not helped, they may need to be tube fed.

This will usually be either:

gastrostomy (a small operation is carried out to insert the tube directly into the stomach)

in rare cases, nasogastric (the tube is inserted through the nose and goes down to the stomach)

The other end of the tube is attached to a bag of high-calorie/nutrient food that is delivered straight to the stomach, usually while the child sleeps.


Adults with cystic fibrosis

Adults who have cystic fibrosis do not need to avoid any particular food, but it is important they have a diet high in protein and energy to maintain their weight. They should eat regular meals and snacks as this helps to maintain energy intake. They should eat three meals a day, including plenty of:

fatty foods – butter, ice cream, chocolate

sugary foods – jam, puddings, sweets

milk and dairy products – cheese, yoghurts

starchy foods – pasta, rice, bread

protein foods – fish, eggs, meat

vitamin/mineral-rich foods – fruit, vegetables

If someone with cystic fibrosis wants to be a vegetarian, they should talk to their dietitian about alternatives to meat. A vegan diet is not advised for people with cystic fibrosis as it tends to be especially low in energy.

Most adults with cystic fibrosis need to continue taking pancreatic enzymes with all fat-containing meals, snacks and drinks. The capsules should be taken before and occasionally during the meal and the number of capsules will vary depending on the fat content of the meal. There are different types and strengths so talking to the cystic fibrosis specialist team will help the person find one that suits them.

Creon is the usual preparation used in the UK. People with cystic fibrosis should not stop taking pancreatic enzymes unless they are told to do so by their dietitian or doctor, as this can lead to a serious blockage of the bowel.

Most adults need to continue taking vitamin A, D, E and K supplements. These come in the form of prescribed multivitamin tablets.

People with cystic fibrosis who lose a lot of weight due to an infection or illness may need to be tube fed to help them gain weight.

As in tube feeding for children, this will be either nasogastric or gastrostomy, depending on how long the tube must stay in for. A gastrostomy tube (which is inserted directly into the stomach) is best for longer periods of time or repeated courses of treatment as it is unlikely to be dislodged during coughing or physiotherapy.



The management of cystic fibrosis with physiotherapy differs for each person with the condition, and is specifically tailored to their needs.

Traditionally, physiotherapy for cystic fibrosis focused mainly on airway clearance (clearing mucus from the lungs). This still makes up a large part of daily treatment, but the role of the physiotherapist in cystic fibrosis has expanded to include daily exercise, inhalation therapy, posture awareness and, for some, the management of urinary incontinence.


Airway clearance

It is beyond the scope of this article to discuss all of the airway clearway techniques available (your care team should be able to provide more information on airway clearway techniques).

The most widely used one in the UK is called active cycle of breathing techniques (ACBT).

Active cycle of breathing techniques (ACBT)

ACBT involves you repeating a cycle made up of a number of different steps. A physiotherapist will explain how to perform the steps and give you advice on when ACBT is necessary.

The steps include:

a period of 20-30 seconds of normal relaxed breathing

3-4 deep breaths, where you hold each breath in for three seconds before breathing out

‘huffing’ – huffing involves taking a medium size breath in followed by a fast breath through your open mouth while using the muscles of your chest and stomach to help force the breath out – this should help push the mucus up to a point where you can cough it out

coughing – you should then cough every 2-3 huffs; but don’t try to force out sputum if it does not feel ready to be coughed out

You then repeat the cycle for 20-30 minutes.

If you are otherwise in good health, you will probably only need to perform ACBT once or twice a day.

If you develop a lung infection, you may need to perform ACBT on a more frequent basis.


Postural drainage

Changing your position can also make it easier to remove mucus from your lungs. This is known as postural drainage.

Each technique can involve a number of complex steps but to summarise, most techniques involve you leaning or lying down while the physiotherapist or a carer uses their hands to vibrate certain sections of your lungs as you go through a series of ‘huffing’ and coughing.


There are also a number of devices that can help remove mucus from your lungs. These include:

the flutter – a handheld device shaped like an asthma inhaler that delivers vibration to the airway of your lungs, making it easier to cough out mucus

RC cornet – a device shaped like a small section of garden hosing which works in much the same way as the flutter

the Acapella – a device shaped like a small torch that uses a combination of vibration and air pressure to help remove mucus

You may have to pay if you want one of these devices. They cost in the region of £45-60.

Some techniques use large pieces of equipment, which can be very expensive and are usually only available for use in a hospital, such as a high frequency chest wall oscillation (HFCWO). This involves using an electric air compressor that connects to an inflatable jacket (vest) to vibrate the chest.



Exercise is recommended for everyone with cystic fibrosis. This may vary from taking part in normal school activities to individualised exercise programmes. Infants and toddlers with cystic fibrosis should have some exercise included in their normal daily routine.

Any sport or exercise that gets a person with cystic fibrosis moving is good, but if there are any concerns or worries, they should ask their physiotherapist.

Children and adults are also encouraged to include stretching exercises into their routine to mobilise the joints and muscles around their chest, back and shoulders, and to be aware of maintaining good posture.



In rare cases, some adults may need long-term home oxygen therapy. This usually involves wearing an oxygen mask or a different device at night.

Lung transplants

In severe cases of cystic fibrosis, when the lungs stop working properly and all medical treatments have failed to help, a lung transplant may be recommended.

Both lungs need to be transplanted as they will both be affected by the condition. A lung transplant is a serious operation that carries certain risks, but it can greatly improve the length and quality of life for people with severe cystic fibrosis.

It is estimated that on average around nine out of 10 people will survive for at least a year after a transplant.

Read the Cystic Fibrosis Trust factsheet on lung transplantation (PDF, 341kb).

The outlook for people with cystic fibrosis is often better than average for transplant patients as they are often younger and in better health than other transplant candidates.



A new medication called ivacaftor helps compensate for the defective CFTR gene, which helps reduce the levels of mucus inside the body.

However, this new treatment is only effective in people who have specific rare types of mutation, such as the G551D mutation, thought to occur in around one in 25 people with cystic fibrosis.

Ivacaftor can be prescribed by specialist centres in England for people with cystic fibrosis who are aged six years and older and have at least one copy of the G551D mutation.

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Cystic fibrosis