Symptoms of Cystic Fibrosis

Cystic fibrosis (CF) symptoms can develop soon after birth and may include salty-tasting skin, greasy and bulky stools, chronic breathing problems, and poor growth. Because the genetic disease interferes with the flow of water and salt in out and out of cells, it causes thickening of mucus that not only clogs the lungs but prevents the pancreas, intestines, liver, and heart from functioning normally.

Over time, the ongoing obstruction of air passages and buildup of mucus can lead to recurrent infections, irreversible lung damage, and other serious complications such as malnutrition, diabetes, and more.

As a progressive disease, cystic fibrosis needs to be treated early to preserve lung function and reduce the inflammatory burden on the body. By doing so, you can avoid many of the severe complications of the disease and maintain a high quality of life for now and years to come.

cystic fibrosis symptoms
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Frequent Symptoms

Many children today are diagnosed with cystic fibrosis before symptoms appear. In the United States, mandatory newborn screening programs can identify CF with one or two simple tests.

Prior to this, around 90 percent of children with CF were only diagnosed when symptoms appeared, usually by the age of two. By that time, many will already have sustained an injury to the lungs and other vital organs.

Despite the advent of newborn screening, only around 65 percent of children are positively diagnosed with cystic fibrosis at birth. 

Among the more common early symptoms of CF:

  • Meconium ileus is the blockage of the baby’s first stool (meconium) in the part of the small intestines knows as the ileum. Because CF can interfere with digestive juices, the meconium can become thicker and stickier than usual, resulting in bowel obstruction. Meconium ileum will affect one of every five newborns with CF and is rarely seen in those without it.
  • Salty-tasting skin is one of the first signs parents may recognize at home. This is caused when the flow of water and salt in and out of cells is obstructed, leading to the excessive accumulation of salt in sweat.
  • Chronic respiratory problems, including wheezing, cough, and colored sputum, are common in children with CF but may vary in severity.
  • Lung infections can also develop as the accumulation of mucus in the lungs provides the ideal breeding ground for bacteria and other microorganisms.
  • Greasy and bulky stools (steatorrhea) are caused by intestinal malabsorption. Because of their high-fat content, the stools will float and be exceptionally foul-smelling. Constipation is also common.
  • Poor growth and weight loss are directly associated with the lack of digestive enzymes (their production can be blocked by the buildup of mucus). Without the means to break down and absorb nutrients, malnutrition can develop even with a healthy diet (and despite a voracious appetite common in nutrient-starved people with CF).

Children who experience these symptoms will often be smaller and weigh less than other children of the same age. Your healthcare provider may describe this as failure to thrive (FTT). 

FTT is more than just a general assessment of your child’s development. It is the decelerated or arrested growth in which a child’s weight and height falls below certain accepted parameters (known as percentiles).

Within the context of cystic fibrosis, FTT is associated with poorer outcomes. In fact, according to a 2014 study published in the Annals of the American Thoracic Society, FTT is the single leading factor for severe CF lung disease.

Poor growth can affect metabolism and interfere with hormones, causing delayed puberty in children with CF by as much as four years.

Late-Stage Symptoms/Complications

The later-stage symptoms of cystic fibrosis are less associated with the disease and more with the damage it has inflicted on organs of the body. While the lungs are primarily affected, the pancreas, intestines, liver, and endocrine (hormonal) system are also commonly involved.

Later-stage symptoms due to complications of CF are often multifactorial with one symptom influencing another, usually for the worst.


When the lungs are clogged with mucus, they can incur damage due to infection, obstruction, and inflammation.

In term of infection, microorganisms that normally inhabit mucus without issue can grow out of control and lead to pneumonia and other infections (including Staphylococcus aureus, Aspergillus fumigatus, Haemophilus influenzae, and Pseudomonas aeruginosa).

People with CF often get recurrent infections which can cause permanent scarring in their lungs.

Meanwhile, the accumulation of mucus in the air passages can increase the blood pressure in the lungs, referred to as pulmonary hypertension. This, in turn, can affect the heart, leading to cor pulmonale (right-sided heart failure). Edema, the abnormal accumulation of fluid in the legs and ankles, is a common symptom.

The accumulative damage can lead to a condition known as bronchiectasis, in which damaged lung tissue makes it all the harder to clear mucus. Symptoms include:

  • Chest pain
  • Chronic cough
  • Wheezing
  • Shortness of breath
  • Sinusitis
  • Coughing up blood
  • Chronic fatigue
  • Inability to exercise
  • Weight loss

Persistent sinus inflammation can cause tissues to thicken and form nasal polyps in up to 86% of people with CF. Symptoms include mouth breathing, nasal drip, and, in some cases, the complete obstruction of nasal passages.


Respiratory failure accounts for roughly 80 percent of deaths in people with CF.

Cardiorespiratory complications (heart and lungs) are the second leading cause.


The accumulation of mucus can also affect the pancreas, the organ responsible for producing digestive enzymes. The impairment of this function, known as pancreatic insufficiency, is at the heart of malnutrition problems seen in people with CF.

Beyond its effect on digestion, the obstruction of enzyme secretions can trigger the painful inflammation of the pancreas, known as pancreatitis. Symptoms include:

  • Sudden and severe abdominal pain
  • Bloating
  • Indigestion
  • Nausea and vomiting
  • Rapid heartbeat
  • Weight loss

Over time, the pancreatic ducts can become completely blocked, resulting in extensive scarring of the organ tissue.

Acute pancreatitis can trigger fatal complications including heart, lung, or kidney failure.

In addition to the pancreatic complications, a bowel obstruction can sometimes occur, either as the result of thicker and stickier stools (referred to as distal intestinal obstruction syndrome in adults) or intussusception (in which part of the intestine folds into the section next to it).

Thickened mucus secretions can also block bile ducts of the liver, leading to the development of gallstones and cirrhosis. In fact, liver disease is the third most common cause of death in people with CF.


When mucus accumulates on the pancreas, it can block the islets of Langerhans, which are responsible for producing insulin. When this happens, it can lead to the development of cystic fibrosis-related diabetes (CFRD), a form of the disease with characteristics of both type 1 and type 2 diabetes.

While CFRD has all of the classic symptoms of diabetes (including increased thirst, increased urination, fatigue, and weight loss), it also characterized by decline in lung function.

Among the other hormone-related abnormalities:

  • Clubbing of the fingers and toes is a characteristic symptom of CF caused, in part, by the release of proteins from the lungs called platelet-derived growth factor (PDGP).
  • Vitamin D, a hormone important to the regulation of calcium and phosphate, is commonly deficient in people with CF. Over time, this can lead to osteoporosis, resulting in brittle bones, loss of height, and an increased risk of bone fractures.


Male infertility in CF is primarily caused by the congenital absence of the vas deferens (the tubes that carry sperm from the testicles to the urethra). The birth defect is associated with the gene that causes CF, called the cystic fibrosis transmembrane receptor (CFTR) gene.

As many as 97% of men with CF will have infertility.

Infertility can also affect women with CF, either due to thick cervical mucus that interferes with conception or chronic malnutrition, which can cause anovulation (the failure to ovulate) and amenorrhea (the failure to menstruate).

Urinary Incontinence

Women with cystic fibrosis who are over age 20 are likely to experience urine leakage to some degree; men do not usually experience this as a result of CF. While the reason why this occurs isn't exactly clear, it's believed that prolonged, frequent coughing from the diseases weakens the pelvic floor muscles.

Coagulation Disorder

In rare cases, cystic fibrosis can lead to a condition known as a coagulation disorder. This is caused by the chronic malabsorption of vitamin K, which is needed for blood clotting. The disorder is believed to affect babies with CF who were unable to absorb vitamin K in the womb, leaving them with low reserves at birth and a limited ability to absorb vitamin K after birth.

Symptoms of coagulation disorder include easy bruising, excessive bleeding, bleeding gums, nosebleeds, and bloody stools or urine.

When to See a Healthcare Provider

Fortunately, with the implementation of newborn screening practices, children with CF are more likely than ever to be diagnosed at birth and placed on immediate treatment. With that being said, many kids still fall through the cracks.

In fact, according to the Cystic Fibrosis Foundation, no less than 6.8 percent of people with CF are diagnosed after the age of 16. There may be several reasons for this:

  • Newborn screening protocols vary by state. Some use a combination of genetic and blood tests taken at the time of birth. Other use only a blood test, which requires a second follow-up visit. In some cases, the parent may fail to bring the child for the second test.
  • The screening tests vary in their accuracy. While the combined genetic and blood tests have a sensitivity of 96 percent, the blood-only test (known as the immunoreactive trypsinogen assay) has a sensitivity of only 76 percent. Lab error is also possible.
  • Some forms of CF are milder than others and may not be readily detected during screening. For those with milder CF, the symptoms may only become apparent later in childhood.

As such, it is important for you as a parent to remain vigilant of the symptoms of CF. Salty-tasting skin is not only the most telling of these symptoms, but it is also the foundation by which the sweat test—considered the gold standard for CF testing—was designed.

Also, you can check to see if your child’s stools are floating, greasy, and foul-smelling. This, along with growth problems and persistent respiratory symptoms, would be enough to warrant an investigation by your child’s pediatrician.

Cystic Fibrosis Doctor Discussion Guide

Get our printable guide for your next doctor's appointment to help you ask the right questions.

Doctor Discussion Guide Child

Frequently Asked Questions

  • How early do babies show signs of cystic fibrosis?

    Within hours of birth, babies may show signs of meconium ileus, an obstruction of the intestines that affects the baby’s first stool. This occurs in about 20% of diagnosed cases of cystic fibrosis (CF). Other symptoms usually appear by age 2. All newborns are screened for CF in the U.S.

  • Is there a mild form of cystic fibrosis?

    Yes. Atypical CF is a milder form of the genetic disease. The symptoms vary widely. In general, though, there may only be one organ affected. Diagnostic tests, especially the sweat test, may come back negative, so the condition can go unnoticed for years. 

  • Are there signs you’re a cystic fibrosis carrier?

    You won’t have any symptoms if you are only a carrier, which means that one of your two CFTR genes has a CF mutation. You may pass CF on to a child if your partner is also a carrier. The only evidence that you’re a carrier would be seen in genetic screening, which can identify up to 90% of CF carriers.

17 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading

By Lori Alma
Lori Alma, RN, is a registered nurse and cystic fibrosis expert who assists families in a Florida Department of Health program for special needs children.