What Are Gastrointestinal Complications of Cystic Fibrosis?

Reviewed by: HU Medical Review Board | Last reviewed: September 2019

Gastrointestinal (GI) problems are the second most common set of issues caused by cystic fibrosis (CF).

The purpose and function of the GI tract

The GI tract is a long tube that runs from the mouth to the anus. It is responsible for turning the food you eat into nutrients that your body can use. The GI organs include the esophagus, pancreas, liver, gall bladder, and small and large intestines.

Common gastrointestinal complications

The most common GI complications that people with cystic fibrosis develop are:

Why do people with cystic fibrosis experience gastrointestinal problems?

GI problems tend to occur in people with CF because the mucus generated by CF clogs the ducts (tubes) leading in and out of the pancreas, liver, and intestines and slows the movements that help food move through the system. This slow movement of bodily waste through the intestines may cause blockages. Blockages make it more difficult for the body to get the nutrients it needs, and may sometimes cause pain, nausea, vomiting, and acid reflux.1

Malnutrition and underweight

The mucus created by CF prevents the body from processing foods and turning that food into nutrients. Additionally, people with CF tend to burn more calories due to the extra work it takes to breathe and fight infections. In fact, people with CF need up to twice the daily recommended calories. These factors contribute to malnutrition and trouble keeping weight on.2

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Doctors prescribe pancreatic enzyme replacements for the 90% of people with CF who have pancreatic insufficiency. Pancreatic enzymes help the person with CF gather enough energy and nutrition from the foods they eat. People with CF are also usually encouraged to eat as much as they’d like of high-calorie, high-fat foods, along with fruits and vegetables.1-3

Research shows that maintaining a healthy weight helps reduce exacerbations and lung infections and improves quality of life. When a person with CF does contract an infection, carrying enough weight helps them fight the infection. A body mass index (BMI) of 22 for women and 23 for men is optimal for those with CF.2

Poor growth in childhood

The same GI issues that cause malnutrition and underweight in adults with CF sometimes make it more difficult for a child with CF to get enough nutrients to grow. That’s because growing requires extra energy and nutrients, on top of the extra calories a child with CF expends breathing and fighting infections compared to a child without CF.

However, a dietitian with a specialty in CF can help a family make sure their child gets enough nutritionally-dense calories without developing eating fatigue. Sometimes people with CF need supplemental tube feedings to get enough calories for growth or weight maintenance.

CF-related diabetes

Up to 50% of people with cystic fibrosis develop a type of diabetes-specific to CF, most often between the ages of 18-30.2 Cystic fibrosis-related diabetes (CFRD) must be handled differently than conventional type-2 diabetes.1

Treatment includes insulin replacement and a high energy diet.1 It is important to manage CFRD closely since high blood sugar levels often lead to more infections and a decrease in lung function.


The pancreas secretes enzymes that help you digest food and releases hormones that help your body regulate blood sugar. If the ducts that connect the pancreas to the intestines become blocked, it can lead to inflammation and cause pain, diarrhea and greasy stools. This is called pancreatitis. It is a rare complication, found in less than 10% of those with CF.4

Liver disease

Only 5-10% of people with CF develop liver disease, though abnormal liver function test results are common in children, ages birth to 10. During the tween and teen years, ages 10-20, cirrhosis may occur in less than 10% of people with CF. For those few who develop cirrhosis (scarring of the liver), portal hypertension may develop in 5-10% of patients and once over age 35, a liver transplant may be needed.1,3

Other gastrointestinal issues

Some other GI issues that tend to happen to people with cystic fibrosis include rectal prolapse and what is commonly called acid reflux.

Gastroesophageal reflux disease (GERD)

GERD occurs when acid from the stomach travels backwards into the esophagus. Heartburn is the most common symptom that this is happening. GERD can be very serious if acid gets into the lungs or if it is not corrected over long periods of time. Other symptoms include repeated vomiting and weight loss.

Rectal prolapse

Rectal prolapse is the term for when the lower part of the colon, called the rectum, falls outside the body. Rectal prolapse occurs in people who are frequently constipated, as people with CF tend to be. Straining to pass hard, bulky stools can cause rectal prolapse.

Colon cancer

Colon cancer is one of those diseases that once was unheard of in children with CF but has now become a more common issue for CF adults because life expectancy has increased so dramatically. Annual screening should begin at age 40, and at age 30 if the person has had an organ transplant.5