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Cystic Fibrosis Symptoms, Causes & Risk Factors

Previously, most people with CF were diagnosed by the age of 2 because of symptoms. In the last decade, newborn screening has become available and is now available in all 50 U.S. states. This means that infants are diagnosed before they have symptoms so that they can begin receiving care as early as possible.

What Are the Symptoms of Cystic Fibrosis?

You or your loved one with CF might experience a wide range in severity of CF symptoms. Even within the same family, siblings can have differing disease severity.

Symptoms of CF can be classified into two main categories: symptoms of respiratory tract disease and symptoms of gastrointestinal disease.

The most common symptoms of CF respiratory tract disease are:

  • Chronic coughing (dry or coughing up mucus)
  • Recurring chest colds
  • Wheezing (that may not respond to standard asthma therapy)
  • Shortness of breath
  • Frequent sinus infections
  • Allergies that last all year

Symptoms of lung disease can start in infancy, especially following upper respiratory viral infections. You'll experience a small but progressive loss in lung function with every passing year, leading to increased symptoms as you age. Some children remain relatively healthy throughout childhood and only start to experience a decline in their lung function when they are teenagers.

The most common symptoms of CF gastrointestinal disease are:

  • Frequent large, greasy, and foul-smelling bowel movements
  • Inability to gain weight despite being hungry all of the time
  • Poor growth
  • Constipation and intestinal blockage
  • Recurrent inflammation of the pancreas (pancreatitis)
  • Symptoms of high blood sugar, such as being thirsty and urinating frequently

Other symptoms:

  • Excessive sweating
  • Your child with CF may taste "salty" when kissed.

What Causes Cystic Fibrosis?

CF is an inherited disorder caused by having two abnormal copies of the CF gene. You cannot catch or acquire CF. It can occur in people who have no known family history of the disease because people with one abnormal CF gene (called “carriers”) are usually healthy.

What Are the Risk Factors?

The only risk factor for getting CF is having two parents who carry abnormal CF genes and pass the abnormal gene to their child. However, there are factors that impact how severe the CF is.

  • Genes: CF gene mutations are divided into classes based on how damaged the CFTR protein function is. Classes I, II, and III are generally more severe causing "classic CF." Classes IV and V are usually milder. Also, other genes called modifier genes can affect a person’s symptoms and outcome.
  • Environment and lifestyle:  People with CF need to consume a very large number of calories to maintain weight and grow, which can be difficult to achieve. Physical activity is also important to help keep lungs healthy. People with CF should not smoke or be exposed to secondhand smoke, as it will worsen lung disease. You should also be careful with alcohol intake, and avoid it altogether if you have liver disease.  
  • Age: CF worsens with age. If you have CF, you usually experience a small decline in lung function each year.

When to See Your Doctor

If you or a loved one have a family history of CF and have pulmonary symptoms, have been diagnosed with CF, or experience these symptoms, consult your healthcare provider and request an evaluation at an accredited CF center. The Cystic Fibrosis Foundation website has a tool to assist in locating a care center.

    This content was developed in partnership with the CHEST Foundation, the philanthropic arm of the American College of Chest Physicians.

    Last updated April 4, 2018.

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