Cystic Fibrosis

Introduction

Cystic fibrosis, often shortened to CF, is a lifelong genetic condition that affects the lungs, the pancreas, and several other organs. People with CF make mucus that is thicker and stickier than normal. Over time, this mucus can block the airways, trap bacteria, and stop the pancreas from releasing the enzymes the body needs to digest food.

If you or your child has been diagnosed with CF, you are likely now thinking about what daily care looks like, which treatments matter most, and what the years ahead may bring. The picture has changed considerably over the last two decades. New medicines that target the underlying genetic defect, better airway clearance routines, careful nutrition, and team-based care at specialist CF centres have all helped people with CF live longer and healthier lives than was possible a generation ago.

This article walks through what cystic fibrosis is, how it is diagnosed, the treatments and daily routines that make up CF care, what changes through childhood and adulthood, and what to watch for as the condition is managed over time. It is written for people with CF and their families who are planning the next stage of care.

What Is Cystic Fibrosis?

Cystic fibrosis is caused by changes (called variants or mutations) in a single gene known as CFTR, which stands for cystic fibrosis transmembrane conductance regulator. This gene gives instructions for making a protein that sits in the surface of certain cells — in the lungs, sinuses, pancreas, intestines, sweat glands, liver, and reproductive system. The CFTR protein moves salt (specifically chloride) and water in and out of these cells. The flow of salt and water keeps the layer of mucus on these surfaces thin and slippery.

Healthy airway surface with thin mucus compared to a CF airway with thick, trapped mucus.

AI-generated illustration

When the CFTR protein is missing, reduced, or does not work properly, the mucus on these surfaces becomes thick and sticky. In the lungs, thick mucus blocks the small airways, traps bacteria, and leads to repeated infections and inflammation. Over many years, this cycle can damage the airways permanently — a condition called bronchiectasis. In the pancreas, thick secretions block the small ducts that should carry digestive enzymes into the intestine, so food is not broken down or absorbed well. CF also affects the sweat glands, which is why a sweat test (measuring salt in sweat) is a key part of diagnosis.

CF is inherited in what is called an autosomal recessive pattern. This means a person develops CF only if they inherit two altered copies of the CFTR gene, one from each parent. A person with just one altered copy is called a carrier. Carriers do not have CF themselves but can pass the variant on to children. When both parents are carriers, each pregnancy has roughly a 1 in 4 chance of the child having CF.

Autosomal recessive inheritance pattern when both parents carry one altered CFTR gene copy.

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More than 2,000 different variants of the CFTR gene have been described. The most common one worldwide is called F508del. The specific variants a person carries influence how CF affects them, how severe it is likely to be, and importantly, which of the newer CFTR-targeting medicines may be suitable.

Types and Classification of CF

Doctors and researchers describe CF in two main ways: by which organs are affected, and by which type of CFTR defect a person has.

Classic and non-classic CF

Most people with CF have what is sometimes called classic CF: lung disease, pancreatic insufficiency (the pancreas cannot release enough digestive enzymes), and high salt in the sweat. A smaller group has non-classic or atypical CF, where the condition is milder or affects fewer systems. Some adults are diagnosed only after years of mild symptoms such as recurrent sinus infections, bronchiectasis, pancreatitis, or male infertility.

CFTR variant classes

CFTR variants are grouped into classes based on what they do to the protein. Some variants stop the protein from being made at all. Others let the protein be made but block it from reaching the cell surface. Others let it reach the surface but stop it from opening properly. These classes matter because the newer CFTR modulator medicines work differently depending on the type of defect.

CFTR-related disorders

Some people have a smaller change in the CFTR gene and develop just one CF-like problem — for example, men with congenital absence of the vas deferens (a cause of male infertility) or people with recurrent pancreatitis without lung disease. These conditions are described as CFTR-related disorders rather than CF itself, but they are managed by similar specialist teams.

Causes and Risk Factors

The cause of CF is genetic. There is nothing a parent does during pregnancy, and nothing the person with CF does or eats, that causes the condition. It is inherited through CFTR variants passed down from both parents.

The carrier rate varies between populations. CF is more common in people of European ancestry, where roughly 1 in 25 people are carriers. CF is less common in people of South Asian, East Asian, and African ancestry, but it does occur, and it is sometimes under-recognised in these populations because of older assumptions that CF is “a European disease.” Diagnosis can therefore be delayed in patients whose ancestry is not European, and clinicians today are more alert to this.

Family history is a relevant factor. If one child in a family has CF, siblings can be tested. If a couple is planning a pregnancy and one or both have a family history of CF, genetic counselling and carrier testing are options to discuss with a specialist.

Signs and Symptoms

For readers who already have a diagnosis, the symptoms listed here help in recognising changes that need attention. CF affects multiple organ systems and the pattern varies from person to person and over time.

Lungs and airways

• Persistent cough, often producing thick sputum (phlegm)
• Frequent chest infections, sometimes called pulmonary exacerbations
• Wheezing and shortness of breath
• Reduced exercise tolerance
• Coughing up blood (haemoptysis), in some people

Sinuses

• Chronic blocked or runny nose
• Recurrent sinus infections
• Nasal polyps (small growths in the lining of the nose)

Digestive system

• Difficulty gaining weight or maintaining weight despite a good appetite
• Bulky, oily, foul-smelling stools (a sign of fat malabsorption)
• Stomach pain and bloating
• In newborns, a blockage of the intestine called meconium ileus can be the first sign
• Older children and adults may develop a similar blockage called distal intestinal obstruction syndrome (DIOS)

Other systems

• Salty-tasting skin
• CF-related diabetes, especially in teenagers and adults
• Liver involvement in some people, ranging from mild changes on blood tests to cirrhosis
• Reduced bone density over time
• Male infertility in most men with CF (due to absence or blockage of the vas deferens), although sperm production is usually normal

A worsening of respiratory symptoms — more cough, more sputum, change in sputum colour, a drop in lung function, weight loss, or fever — is described as a pulmonary exacerbation and usually needs prompt review by the CF team.

Diagnosis

CF is most commonly diagnosed in one of three ways: through newborn screening, after symptoms appear in infancy or childhood, or — less often — in adulthood after years of milder, unexplained problems.

Newborn screening

Many countries now include CF in routine newborn blood-spot screening. The screen measures a substance called immunoreactive trypsinogen (IRT), which is often raised in newborns with CF. A positive screen is followed by confirmatory testing — usually a sweat test and genetic testing — before a diagnosis is made. Newborn screening is not universal worldwide; where it is not in place, CF is usually diagnosed after symptoms appear.

Sweat test

The sweat chloride test is the standard diagnostic test for CF. A small area of skin (usually on the arm or leg) is stimulated to produce sweat, which is collected and tested for its chloride concentration. A high level supports a diagnosis of CF; a borderline result may need repeat testing or further evaluation.

Genetic testing

Genetic testing identifies the specific CFTR variants a person carries. This confirms the diagnosis, gives information about likely severity, and — importantly — determines whether the person may be eligible for a CFTR modulator medicine, because these treatments work only with certain variant types.

Additional tests at diagnosis and follow-up

• Chest X-ray or CT scan to look at the lungs
• Sputum culture to identify which bacteria are present in the airways
• Lung function tests (spirometry) once a child is old enough to perform them
• Tests of pancreatic function, such as faecal elastase
• Blood tests for liver function, vitamin levels, and blood sugar
• Bone density assessment in older children and adults

After diagnosis, the person is usually referred to a specialist CF centre, where care is delivered by a multidisciplinary team that typically includes a CF physician, specialist nurses, physiotherapists, dietitians, social workers, and psychologists.

Treatment and Management

CF care is lifelong and has several aims at the same time: keeping the airways clear, treating infection, supporting nutrition, addressing the underlying CFTR defect where possible, and managing complications as they arise. Treatment is personalised, and the daily routine is often substantial many people with CF spend an hour or more each day on therapies. The aim of every part of treatment is to slow lung damage and keep the person as well as possible for as long as possible.

Airway clearance

A person using a handheld oscillating PEP device during an airway clearance session.

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Clearing mucus from the lungs is one of the central tasks in CF care. Several techniques are used, usually taught by a specialist physiotherapist. The right combination depends on age, lung function, and personal preference.

• Chest physiotherapy with manual percussion and postural drainage, used especially in young children
• Breathing techniques such as the active cycle of breathing technique (ACBT) and autogenic drainage
• Positive expiratory pressure (PEP) devices and oscillating PEP devices (such as Flutter or Acapella)
• High-frequency chest wall oscillation using a vibrating vest, where available
• Exercise, which is consistently emphasised in CF care as both an airway clearance and a general health intervention

Most CF care guidelines, including those from the Cystic Fibrosis Foundation and the European Cystic Fibrosis Society, recommend daily airway clearance, even when the person feels well.

Inhaled medicines

Several inhaled medicines support airway clearance and reduce infection:

• Hypertonic saline — a salty solution inhaled as a mist that helps hydrate and loosen mucus
• Dornase alfa — an enzyme that breaks down DNA in thick sputum, making it easier to clear
• Inhaled antibiotics such as tobramycin, aztreonam, or colistin, used long-term when the airways are chronically infected with bacteria such as Pseudomonas aeruginosa
• Bronchodilators, used by some people, particularly before airway clearance or exercise

Treating infections

Repeated and chronic airway infections are central to CF lung disease. Sputum cultures are taken at routine visits to track which bacteria are present. Common organisms include Staphylococcus aureus, Haemophilus influenzae, Pseudomonas aeruginosa, and, less commonly, Burkholderia cepacia complex and non-tuberculous mycobacteria.

Oral antibiotics are used for milder exacerbations. Intravenous (IV) antibiotics — often for 10 to 14 days — are used for more severe exacerbations and can be given in hospital or, in some centres, at home. When Pseudomonas is first found in the airways, an “eradication” course of antibiotics is usually attempted to clear it before chronic infection sets in.

CFTR modulator therapy

CFTR modulators are a group of medicines that target the underlying CFTR protein defect rather than just treating symptoms. They have changed the outlook for many people with CF over the last decade.

Schematic showing a defective CFTR protein at the cell surface corrected by modulator therapy to restore function.

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The main CFTR modulators in use include ivacaftor, lumacaftor/ivacaftor, tezacaftor/ivacaftor, and the triple combination elexacaftor/tezacaftor/ivacaftor. The triple combination has been shown in clinical trials to improve lung function, reduce exacerbations, improve nutritional status, and improve quality of life in eligible patients.

Eligibility depends on the specific CFTR variants a person carries; not all variants respond. Availability of these medicines varies between countries and healthcare systems, so whether a particular modulator is an option in a given setting is a discussion to have with the CF team. For patients who cannot take a modulator, the rest of CF care — airway clearance, infection treatment, nutrition — remains the foundation of management.

Nutrition and pancreatic enzyme replacement

Most people with CF have pancreatic insufficiency and need pancreatic enzyme replacement therapy (PERT) — capsules taken with every meal and snack to help digest fat, protein, and carbohydrate. The dose is adjusted by the dietitian based on weight, growth, stool symptoms, and the fat content of meals.

CF traditionally requires a higher-calorie, higher-fat diet than is usual, because energy needs are increased and absorption is impaired. People with CF are also at risk of low levels of the fat-soluble vitamins A, D, E, and K, so these are supplemented. Salt requirements are higher than usual, particularly in hot weather and during exercise.

Nutritional needs are evolving as CFTR modulators improve absorption and appetite. Some people taking modulators gain weight more easily than before, and dietary advice may need to shift accordingly. Working with a CF dietitian is an ongoing part of care.

Managing complications

• CF-related diabetes is increasingly common with age and is managed mainly with insulin. Annual screening with an oral glucose tolerance test usually begins in adolescence.
• CF liver disease ranges from mild blood test changes to cirrhosis. Ursodeoxycholic acid is sometimes used; advanced liver disease may require specialist hepatology input or, rarely, liver transplant.
• Sinus disease and nasal polyps are often managed with nasal saline, nasal steroids, and sometimes sinus surgery.
• Low bone density is screened for and managed with vitamin D, calcium, weight-bearing exercise, and other treatments when needed.
• Distal intestinal obstruction syndrome (DIOS) requires prompt review and specific treatment.

Lung transplantation

When CF lung disease becomes very advanced and other treatments are no longer enough, lung transplantation is one option that CF teams may consider. Referral for transplant assessment is based on a combination of lung function, frequency and severity of exacerbations, oxygen requirements, and overall condition. Transplantation does not cure CF — the new lungs are not affected by CFTR, but the rest of the body still is — and it brings its own significant risks and lifelong follow-up. Whether and when to consider transplant is a careful discussion between the patient, family, and CF and transplant teams.

Lifestyle and Self-Management

Daily life with CF involves a substantial set of routines. Many of them become habitual over time, but they take effort, and the support of family and the CF team matters.

Daily routines

• Airway clearance sessions, usually once or twice a day
• Inhaled medicines on schedule
• Pancreatic enzymes with every meal and snack
• Vitamin and salt supplements
• CFTR modulator medicines, where prescribed
• Cleaning and maintaining nebulisers and other equipment

Exercise

Regular physical activity is one of the most consistent recommendations in CF care. Exercise helps with airway clearance, lung function, bone health, mood, and overall fitness. The type of exercise can be tailored to the person — swimming, cycling, team sports, gym work, yoga, dance — and CF physiotherapists can help design a programme that fits.

Infection prevention

Some bacteria that cause infection in CF can be passed between people with CF. Specialist CF centres take this seriously and separate patients with different infection profiles in clinic. People with CF are generally advised not to meet other people with CF in person and to follow good hand hygiene, avoid sharing nebulisers, and stay up to date with vaccinations (including influenza, pneumococcal, and others recommended by the CF team).

Mental and emotional health

Living with a complex, lifelong condition affects mental health. Rates of anxiety and depression are higher in people with CF and in their parents than in the general population. CF care guidelines now recommend regular screening for anxiety and depression as part of routine visits. Psychological support — through CF team psychologists, counselling, or peer support — is part of comprehensive care.

Smoking and avoiding lung irritants

People with CF are strongly advised not to smoke and to avoid second-hand smoke and other lung irritants such as vaping, wood smoke, and heavy air pollution where possible.

Monitoring and Follow-up

CF is monitored carefully over time at a specialist CF centre. Routine reviews typically happen every two to three months, with more frequent visits during exacerbations or other concerns. A typical review may include:

• Symptom review — cough, sputum, energy, appetite, weight
• Weight, height (in children), and growth tracking
• Lung function tests (spirometry)
• Sputum culture
• Discussion of treatment adherence and what is working
• Mental health check-in

An annual review usually adds blood tests (liver function, vitamins, blood sugar screening), chest imaging when indicated, bone density scans periodically, and detailed assessment by each member of the multidisciplinary team.

Complications

Even with good care, CF can lead to complications over time. Knowing what to watch for helps people and families recognise problems early.

Pulmonary exacerbations

An increase in cough, change in sputum, breathlessness, weight loss, fever, or a drop in lung function suggests an exacerbation. These episodes need prompt review, because each can cause a step-down in lung function that may not fully recover.

Bronchiectasis and chronic infection

Long-term inflammation and infection cause widening and scarring of the airways (bronchiectasis), which makes mucus clearance harder and infection more persistent.

Haemoptysis and pneumothorax

Coughing up blood (haemoptysis) can range from streaks in sputum to larger volumes, and large bleeds need emergency care. Pneumothorax (collapsed lung) can also occur and causes sudden chest pain and breathlessness — this is a medical emergency.

CF-related diabetes

This becomes more common with age and is screened for from adolescence onwards.

Liver disease, bone disease, and arthritis

These are recognised long-term complications and are monitored at annual reviews.

Fertility

Most men with CF are infertile because of congenital absence or blockage of the vas deferens, although sperm production is usually normal. Surgical sperm retrieval and assisted reproductive techniques are options that fertility specialists can discuss. Women with CF can usually become pregnant, although pregnancy in CF needs specialist joint care with obstetrics and the CF team to monitor lung function, nutrition, and diabetes.

Cystic Fibrosis in Children

CF in children is the most common context in which the diagnosis is made, and many of the principles above apply from infancy. There are several considerations specific to children.

Infancy and early years

For babies diagnosed through newborn screening, treatment usually starts early, before serious symptoms appear. Care in the first year focuses on:

• Establishing weight gain and growth — with pancreatic enzyme replacement, vitamin supplements, and salt as needed
• Starting airway clearance routines, often parent-assisted at first
• Monitoring for early lung infections and treating them promptly
• Family education and support

Some babies present with meconium ileus — a blockage of the bowel in the first days of life — which may require surgery.

School years

As children grow, they take a more active role in their own care. Parents and CF teams work with schools to allow time and privacy for pancreatic enzymes, treatments, and any extra snacks. Children with CF can usually take part in physical activity and sports, which is actively encouraged. Infection-control measures may apply at school, particularly avoiding close contact with other children who have CF.

CFTR modulators in children

CFTR modulator medicines have been approved progressively for younger age groups as evidence has accumulated. The age at which a particular modulator can be started depends on the specific medicine, the child’s variants, and local approvals.

Adolescence and transition to adult care

Adolescence is a time of physical and emotional change. CF-related diabetes screening usually begins around age 10. Issues such as treatment adherence, body image, mental health, sexuality, fertility, and future planning become important. Most CF centres run a structured transition programme to move young people from paediatric to adult CF care over a period of one to two years, so that the change happens gradually and with continuity.

Timeline of the typical CF transition process from adolescence through transfer to adult specialist care.

AI-generated illustration

Living with Cystic Fibrosis

Outlook in CF has changed significantly. With newborn screening, specialist centre care, better airway clearance, more effective antibiotics, careful nutrition, and CFTR modulator therapy for eligible patients, median survival has risen substantially in recent decades. Many people with CF now live well into adulthood, study, work, build relationships, have children, and pursue the things that matter to them.

Day-to-day, the demands of CF care — the time, the routines, the appointments, the financial and emotional load on families — remain real. Most CF teams now include or have access to social workers and psychologists for exactly this reason. Peer support through CF charities and online communities (with appropriate infection precautions) can be valuable for both adults and parents.

Work and study are usually possible, and reasonable adjustments — flexibility around appointments, time for treatments, recovery from exacerbations — can be discussed with employers and educational institutions. Travel is generally possible but takes planning: maintaining medicines, equipment such as nebulisers, and access to specialist care at the destination are all worth thinking through with the CF team in advance.

Family Planning and Genetics

Because CF is genetic, family planning brings specific questions. Parents of a child with CF can be offered carrier testing for future pregnancies and genetic counselling to understand inheritance. Adults with CF who are planning a family can also consider carrier testing of partners. Options that may come up in genetic counselling include natural conception with prenatal testing, in vitro fertilisation with pre-implantation genetic testing, and use of donor gametes. Each option has medical, ethical, and personal dimensions, and these are discussed with a clinical geneticist or fertility specialist as appropriate.

When to Seek Urgent Care

People with CF and their families learn over time which changes need a routine call to the CF team and which need more urgent attention. The list below is a general guide; the CF team will give personalised guidance.

Contact the CF team promptly for:

• A new increase in cough or change in sputum colour or volume
• New breathlessness or wheeze
• Fever
• Unexplained weight loss
• Streaks of blood in sputum
• Worsening abdominal pain or change in bowel habit

Seek emergency care for:

• Large amounts of blood coughed up
• Sudden severe chest pain or sudden severe breathlessness (possible pneumothorax)
• Severe abdominal pain with vomiting and no bowel movements (possible DIOS or bowel obstruction)
• Signs of severe infection — very high fever, confusion, very rapid breathing

Frequently Asked Questions

Is cystic fibrosis curable?

CF is not currently curable. However, treatment has improved dramatically. CFTR modulator medicines target the underlying protein defect for many — though not all — people with CF and can substantially improve lung function, weight, and quality of life. Research into gene therapy and other approaches that aim to address the genetic cause is ongoing.

How is CF passed on to children?

CF is inherited in an autosomal recessive pattern. A person develops CF only if they inherit two altered copies of the CFTR gene, one from each parent. People with only one altered copy are carriers and do not have CF. When both parents are carriers, each pregnancy has roughly a 1 in 4 chance of resulting in a child with CF.

Can people with CF play sports and exercise?

Yes, and they are actively encouraged to. Exercise is one of the most consistently recommended parts of CF care. The type and intensity should be tailored to the individual, and the CF physiotherapist can help design a programme.

Why are people with CF told not to meet each other in person?

Some bacteria that cause lung infection in CF, such as Pseudomonas aeruginosa and Burkholderia cepacia, can be passed between people with CF and are very difficult to treat once acquired. Infection-control practice in CF care therefore recommends keeping people with CF physically apart, including at clinics, in hospital wards, and at social events.

Can adults be diagnosed with CF?

Yes. Some people with milder CFTR variants are diagnosed in adolescence or adulthood after years of recurrent sinus infections, bronchiectasis, pancreatitis, or unexplained infertility. Adult diagnosis is less common than childhood diagnosis but is recognised.

Can women with CF have children?

Many women with CF can become pregnant. Pregnancy in CF needs careful joint care between the CF team and an obstetrician experienced in high-risk pregnancy, with attention to lung function, nutrition, diabetes, and medication safety. Most men with CF are infertile due to absence or blockage of the vas deferens, but sperm production is usually normal and surgical sperm retrieval with assisted reproduction is an option to discuss with a fertility specialist.

Do CFTR modulators work for everyone with CF?

No. CFTR modulators only work for people whose CFTR variants produce a protein that the medicine can act on. Genetic testing identifies which variants a person has and whether they may be eligible. People whose variants are not responsive to current modulators rely on the other components of CF care — airway clearance, inhaled treatments, antibiotics, nutrition — and research is ongoing to develop therapies that may help a wider group.

How often will we see the CF team?

Routine reviews at a specialist CF centre are usually every two to three months, with an annual in-depth review and additional visits during exacerbations or other concerns. The CF team is also available between visits for new symptoms or questions.

Conclusion

Cystic fibrosis is a complex, lifelong condition, but it is also one in which clinical care has changed dramatically within a single generation. The combination of early diagnosis through newborn screening, organised multidisciplinary care at specialist CF centres, careful daily routines for airway clearance and nutrition, prompt treatment of infections, and CFTR modulator medicines for eligible patients has shifted the outlook for many people with CF.

The daily work of CF care is significant, and it is shared between the person with CF, their family, and the CF team. Understanding the condition, knowing what to watch for, keeping in regular touch with the specialist team, and finding sustainable routines that fit into the rest of life are all part of living well with cystic fibrosis. Decisions about specific treatments — which modulator, which airway clearance method, when to consider transplant, how to handle a particular complication — are individual ones, made together with the CF team based on the person’s genetics, current condition, and preferences.