• Posted June 24, 2025

Cystic Fibrosis: Symptoms, Treatments, Causes & More

Cystic fibrosis (CF) is a rare autosomal recessive disorder that affects numerous systems of the body. It is a complicated disease that differs from person to person. 

An autosomal recessive disorder is a genetic condition in which an affected person has inherited a mutated gene from each parent.

In CF, mutations in the CF transmembrane conductance regulator (CFTR) gene can cause the CFTR protein to malfunction. The CFTR protein acts like a channel, helping to control the flow of salt and water in and out of the cell. 

Also in CF, the protein is faulty or missing, so chloride gets trapped in the cells, preventing water from being drawn to the cell surface. Thick, sticky mucus then builds up, causing serious problems in many organs, including the lungs and digestive system.

An estimated 40,000 children and adults in the United States live with cystic fibrosis, with about a thousand new cases of CF diagnosed every year. More than 75% of people with CF are diagnosed early in life. 

Despite the disease’s complexity, people with CF lead fulfilling lives: They go to school and college, get married and have children, socialize, work, retire and do activities they enjoy.

Due to therapeutic advances, most of the CF population is now 18 and older; the median age of survival is 65 years for those born between 2020 and 2024, according to the Cystic Fibrosis Foundation’s 2024 Patient Registry. 

That compares to 46.2 years for those born between 2015 and 2019. (Median means half live longer, half have shorter lives.)

Symptoms

People with CF experience a variety of symptoms, each with its own level of severity. Each patient’s experience is affected by the type of CF mutations, characteristics such as age, gender and race, sex hormones, financial constraints and access to quality CF care. When a person ages, additional complications occur. These may be a function of medication side effects, medical history and nutrition.

Respiratory system:

• Pulmonary congestion and infection: People commonly experience a chronic, productive cough and have frequent lung infections caused by virulent bacteria. Patients need oral or intravenous antibiotics to resolve any lung infections.

• Wheezing: When lung inflammation occurs, a person will experience wheezing. This results from constricted airways (asthma) that make breathing difficult. Usually, people with CF use an inhaler to open their airways quickly.

• Sinus congestion and infection/nasal polyps: Thick, sticky mucus causes sinus congestion, which may lead to infections. Patients often perform daily nasal rinses to clear mucus from their sinus passages. Inflammation and congestion can also cause sinus migraines. Nasal polyps (soft, painless growths inside the nasal passages caused by irritation and inflammation) commonly occur in CF and are usually benign (non-cancerous).

• Digital clubbing: Clubbing in the fingers is usually a symptom of oxygenation issues due to lung, heart or digestive problems, all of which occur in CF.

Gastrointestinal system:

• A range of gastrointestinal issues: Individuals may also experience distal obstructive intestinal syndrome (DIOS), gastroparesis, small bowel bacterial overgrowth and gastroesophageal reflux disease (GERD). DIOS occurs when thickened intestinal contents block a portion of the small intestines; it may lead to bowel obstruction. DIOS happens in about 20% of adults with CF, usually in persons who experience pancreatic insufficiency. Gastroparesis is when the stomach empties more slowly than usual after eating. It may cause bloating and nausea. Small bowel bacterial overgrowth results from the repeated use of antibiotics, which may kill the good bacteria and cause the harmful bacteria to overgrow in the intestine. Overgrowth causes gas, diarrhea, nausea and bloating. People may also experience heartburn or reflux (GERD symptoms) after eating or drinking certain foods or beverages. Over-the-counter or prescription medicines may help reduce GERD.

• Liver disease: CF may cause gallstones, fatty liver disease, liver fibrosis and multiple lobe liver scarring. These conditions may lead to high blood pressure in the veins that move blood from the digestive tract to the liver, which can ultimately cause liver failure. About 5% to 10% of people with CF develop liver disease.

Endocrine system:

• CF-related diabetes (CFRD): CFRD occurs in about 19% of people with CF and has similarities with diabetes. It is a condition in which the pancreas does not make enough insulin, like in type 1 diabetes. CFRD is also a condition of insulin resistance, which is common among people with type 2 diabetes. People with CFRD may have insufficient insulin production because of pancreatic scarring, which results from chronically having thick mucus in the pancreatic ducts. The scarring prevents the pancreas from producing enough insulin. Symptoms of CFRD include excessive fatigue, increased thirst, increased urination, weight loss or difficulty gaining weight, increased respiratory problems (pulmonary exacerbations) and an unexplained decline in lung function.

• CF-related bone disease: People with CF may develop osteopenia or osteoporosis due to a lack of bone minerals. A chronic history of steroid use may also lower bone density. Osteopenia and osteoporosis result from low bone density and may cause bones to break. Vitamin D and K supplements can help prevent CF-related bone disease, as can weight-bearing exercise and good nutrition. To catch the development of bone disease, endocrinologists track pubertal development and bone density measurements in patients. If a person has osteopenia or osteoporosis, their doctor may prescribe bisphosphonates or other medicines.

Circulatory system:

• High cholesterol, blood pressure and cardiovascular disease: Increased weight gain and obesity for patients on modulators may lead to elevated levels of blood lipids such as cholesterol (hyperlipidemia), higher blood pressure, and, in some cases, cardiovascular disease. Thus, an increased risk of heart disease is becoming a diagnosis of concern for those aging with CF on modulators.

Urinary system:

• Kidney disease: People with CF may develop high blood pressure (hypertension) and kidney disease because of medications, pulmonary/heart issues and other CF complications. CF-related kidney disease may lead to the need for dialysis or a kidney transplant.

Musculoskeletal system:

• Kyphosis is an excessive forward rounding of the upper back, usually caused by years of coughing and decreased bone density in CF. Individuals may do special exercises to counteract kyphosis.

Immune system: 

• Many people with CF have weakened immune systems. Because of their susceptibility to infections and the harsher consequences of getting the flu, COVID-19, RSV and colds, people with CF must avoid as many bacteria and viruses as possible. Further, individuals who receive an organ transplant (usually lungs) due to CF must take anti-rejection medications that produce an immunocompromised state.    

Other symptoms: 

• Salty-tasting skin due to faulty sodium chloride exchange.

• Dental issues and gum disease: Dental and gum problems in CF have a variety of causes: bacteria that cause cavities (caries), saliva composition, and reduced saliva flow; gastroesophageal reflux disease (GERD); and frequent antibiotic use, which may weaken tooth enamel. Systemic inflammation may also contribute to gum disease. Therefore, people with CF are at higher risk of tooth decay and gum disease. 

• Pain: Individuals may experience pain from medical procedures, therapeutic interventions and the disease itself, including joint pain caused by systemic inflammation. Pain may increase the number of respiratory episodes (pulmonary exacerbations), interfere with daily activities, intensify mood changes and lower quality of life. Pain may be treated with physical therapy, medications, exercise and massage. Sometimes, however, these therapies are difficult to access due to cost.

• Headaches: CF patients experience sinus headaches and other types (migraines) due to congestion, dehydration and medication side effects.

• CF patients often experience depression and/or anxiety due to daily stresses, poor prognosis, treatment burden and lack of social support.

• Fatigue: Many CF patients are fatigued due to chronic infections, sleep disturbances and the overall burden of disease and treatments. Fatigue may cause neurocognitive symptoms like brain fog or memory loss and impact daily activities.

When to see a doctor about cystic fibrosis

Genetic testing before and after birth can detect cystic fibrosis. Parents should contact a doctor if a child has significant difficulty gaining weight, complains of stomach aches, has greasy stools, recurrent lung and sinus infections, salty skin and a productive cough throughout the day and night. A child may also be born with a blockage in the small intestine (meconium ileus), requiring surgery.

Adults with suspected CF should also contact a doctor if they have these symptoms, along with fatigue, pain and difficulty conceiving (if trying to have a child). A “late” diagnosis after years of having CF symptoms is not uncommon. Once diagnosed, it is essential to see a cystic fibrosis doctor to have access to a team of experts and the most updated medications and therapies.

How is cystic fibrosis diagnosed?

Genetic testing may detect gene mutations in cystic fibrosis. People can get a blood test to determine whether they are carriers. A doctor may take blood from an infant’s heel to test for high levels of immunoreactive trypsinogen (IRT) released from the pancreas, which could signal CF. 

But more tests are needed to confirm the diagnosis, so those suspected of having cystic fibrosis (due to nasal polyps, chronic sinus and/or lung infections, repeated pancreatic inflammation, thickened pulmonary airways or male infertility) may get a sweat chloride test (to test for salt on the skin) or a nasal differential test to confirm the diagnosis and learn about their CFTR mutations. 

Knowing one’s mutations can help identify which mutation-specific medications may be appropriate.

How is cystic fibrosis treated?

Cystic fibrosis treatments have undergone enormous changes in the past five years. New cystic fibrosis transmembrane conductance regulator medicines (e.g., modulators) have revolutionized CF treatment in the United States and extended the lifespan of patients who qualify for them. 

Treatments for CF used to address symptoms, but now, modulator therapy instead addresses the faulty CFTR protein. 

The therapy has two mechanisms: It either opens the CFTR channel to enable salt and water to move more freely, or it helps the CFTR protein fold into a corrected shape to function correctly. It thins mucus and increases patients’ lung function with these adjustments. It also reduces other CF symptoms throughout the body that are related to the presence and production of mucus. 

Ten percent of the CF population is not eligible for modulator therapy. Other treatments are being studied that target this group.

In addition to modulator therapy, CF patients undergo daily inhalation treatments with bronchodilators to ensure their airways stay open and they can breathe effectively. Parents are encouraged to have their children stay active to aerate their lungs and expel phlegm to avoid breeding infections. 

Now, on modulators, some people are adjusting their treatment regimen, which may be time-consuming, because modulator therapy has dramatically improved their health. Typical home treatments (bronchodilators, airway clearance, antibiotics), however, are still in use.  

Despite daily treatments, CF patients, on modulators or not, are sometimes hospitalized, and if their disease becomes too severe, transplant specialists assess them for a lung transplant.    

Physicians prescribe antibiotics (oral, inhaled or IV) to treat pulmonary infections. The type of antibiotic prescribed depends on which bacteria appear in the mucus when cultured. 

Patients perform daily airway clearance (e.g., the Vest, machine percussor, hand percussion, cardio exercise) to loosen the thick mucus and cough it up to avoid lung infections. Patients take pancreatic enzymes to digest food properly. 

They take reflux medications, steroids, mucus thinners, insulin (for those with CFRD), serotonin-uptake inhibitors (SSRIs) and other drugs, depending upon their complications. People with CF also get recommended vaccinations to help stave off infectious diseases like flu, COVID-19, RSV and measles.

Causes of cystic fibrosis

Cystic fibrosis is an autosomal recessive genetic disease, meaning both parents must be carriers of one of the hundreds of genetic mutations. 

If two people have mutations, their fetus has a 1 in 4 chance of having a CF genotype. 

New research is showing that carriers of CF may also have digestive and respiratory symptoms (though not as severe as those with CF) and higher cancer risks (but lower than the CF population) compared to the general population.

Risk factors

Due to compromised immune systems, people with CF are at higher risk of catching viruses and pneumonia. They are also at higher risk for a variety of cancers, including colon, pancreatic and breast. 

CF patients may, therefore, undergo cancer screenings earlier and sometimes more often than generally recommended. 

Patients who age with CF are frequently at risk of osteopenia and osteoporosis, cardiovascular disease, cystic fibrosis-related diabetes and obesity.

Living with cystic fibrosis

Cystic fibrosis may profoundly impact daily life when the patient is sick (has a lung or sinus infection or other CF-related illnesses). Life may be less affected if the patient is not ill. 

Cystic fibrosis treatments require several hours a day, so the treatment burden may be challenging and impact the time and energy patients have to work or have a personal life. Some patients go on Social Security Disability Insurance (SSDI) because they are no longer able to work and need to focus on doing their medical treatments to stay alive.

CF teens and adults often worry about disability prejudice and discrimination against them in school, dating, employment or other social settings. When they need peer support, people with CF and their caregivers may join a robust community that actively engages in social media groups and online retreats and conferences. 

Due to cross-infection risk, people with CF are advised not to meet in person or, if they do, to be six feet apart and wear masks to limit their risks. Thus, the CF community has developed a rich set of peer support activities (online yoga, discussion groups and advocacy groups) to find social connections.

Cystic fibrosis and pregnancy 

Females with cystic fibrosis used to have difficulty conceiving because of thick mucus caused by CFTR dysfunction, which made it more difficult for sperm to penetrate the cervix. The latter may extend the time it takes to become pregnant.

Modulator therapy has thinned cervical mucus, making it easier for females to conceive. With improved health due to modulator medicines, more females are now getting pregnant and giving birth. Ongoing studies are investigating whether it is safe to take modulator therapy during pregnancy.

All pregnancies with CF are considered high-risk, so a high-risk obstetrician follows pregnant people to limit significant impacts on their pulmonary, endocrine and nutritional health. CF providers collaborate with these obstetricians to manage any pulmonary exacerbations, the development of gestational diabetes and other complications.

Most males with CF are infertile because they are born without vas deferens, the ducts that transport sperm from storage to the urethra for ejaculation. Many couples facing this situation seek assisted reproductive technology to conceive. Because of the lack of the sperm canal, the sperm is unable to reach the semen, which causes the inability to fertilize an egg during sex.

Having an absence of sperm in the semen may lead to thinner ejaculation and lower semen volume in males with CF compared to their non-CF peers. Many couples seek assisted reproductive technology to have biological children in this instance.

Health risks, family and financial situations, life goals and other influences shape people with CF’s family-building decisions. Because CF treatments are costly, many patients do not have the financial means to have a child.

Others feel they do not have adequate support systems to manage child-rearing and staying healthy. Still, others are wary of a high-risk pregnancy. If they still want biological children, they may pursue surrogacy or assisted reproductive technology.

If they decide against biological parenthood, some CF patients adopt or foster children, and others choose not to have a child or become stepparents.

About the expert

Sandy Sufian, PhD, MPH, holds joint appointments in the University of Illinois Chicago (UIC) Department of Medical Education in the College of Medicine (Health Humanities) and the Department of Disability and Human Development in the College of Applied Health Sciences. She co-founded the Cystic Fibrosis Reproductive and Sexual Health Collaborative (cfreshc.org) and has received numerous grants from the Patient-Centered Outcomes Research Institute, the Cystic Fibrosis Foundation and the National Endowment for the Humanities.