Symptoms of cystic fibrosis

Last updated March 14, 2023, by Marisa Wexler, MS
Fact-checked by José Lopes, PhD

Cystic fibrosis (CF) is a genetic disease that can cause a wide range of symptoms, including serious lung infections and severe digestive problems. The inherited disorder is characterized by the production of thick, sticky mucus that builds up in the body’s organs, particularly the lungs, pancreas, liver, and intestine. This mucus can interfere with organ function and promote inflammation and tissue damage.

CF is caused by mutations in the gene that codes for the protein CFTR, which normally helps control the movement of salt and water molecules in and out of cells. These CFTR gene mutations lead to problems with protein production and processing, resulting in insufficient CFTR protein activity that ultimately causes the production of thick mucus.

The symptoms of CF begin to develop soon after birth. They can vary in severity significantly between patients and may ease or worsen with time. An individual patient may not experience all of the symptoms associated with CF, and some symptoms may not manifest until adolescence or adulthood.

Respiratory symptoms

Cystic fibrosis results in respiratory symptoms that may include:

• wheezing and shortness of breath
• chronic cough
• ongoing or frequent lung infections
• runny nose and congestion
• non-cancerous growths in the nose
• enlarged heart
• collapsed lung.

The thick, sticky mucus that characterizes CF tends to build up in the airways of the lungs, blocking airflow and causing lung inflammation. This leads to respiratory symptoms such as shortness of breath and a persistent cough. Clubbing, or rounding in the tips of the fingers and toes, may occur if the body is not getting enough oxygen.

The mucus buildup that marks CF provides a fertile breeding ground for bacteria. As such, people with CF commonly experience recurrent lung infections, which can lead to more damaging lung inflammation. A particular species of bacteria called Pseudomonas aeruginosa is frequently involved in serious lung infections among people with cystic fibrosis.

CF also may cause inflammation in the nose and sinuses, leading to symptoms like congestion and a runny nose. Growths or swelling in the nose, called nasal polyps, also may develop. This can block the sinuses and lead to breathing difficulties.

As lung damage in cystic fibrosis progresses, patients may develop serious problems, such as a collapsed lung, called a pneumothorax, or pulmonary hypertension, which occurs when the blood pressure in the blood vessels that supply the lungs is abnormally high. Pulmonary hypertension can put a strain on the heart and cause it to become enlarged.

Digestive symptoms

Common digestive symptoms in CF include:

• frequent stools that are especially bulky, greasy, and stinky
• poor growth and difficulty putting on weight
• constipation
• stomach pain
• heartburn
• bloating and flatulence
• intestinal blockages
• gallstones
• liver disease.

The thick mucus that characterizes CF often builds up in the pancreas, an organ near the stomach that’s normally responsible for making the enzymes that break down foods in the body. The accumulation of mucus in the pancreas causes clogs, inflammation, and tissue damage. In fact, damage to that organ is how CF gets its name — the disease tends to cause fluid-filled growths (cysts) and scarring (fibrosis) in the pancreas.

The enzymes produced in the pancreas help to break down foods, particularly fats, proteins, and starch. When the organ gets clogged, these enzymes cannot move out of the pancreas into the digestive tract. Without enough digestive enzymes, CF patients may have difficulty breaking down food and absorbing it properly. This can cause patients to not absorb enough nutrients and calories from their food; as a result, many CF patients, especially children, have poor weight gain and growth.

The lack of digestive enzymes in CF also can contribute to bouts of abdominal pain, constipation, and smelly, greasy stools. Frequent straining due to constipation and coughing can increase the risk of rectal prolapse, where part of the intestine pokes out of the anus. This condition typically requires surgery to fix.

Damage to the pancreas also can cause problems with insulin, a hormone that normally helps to regulate blood sugar levels. Due to this damage, many people with CF develop a specific form of diabetes known as CF-related diabetes or CFRD.

Thick CF mucus also can build up in the intestines to cause blockages, leading to distal intestinal obstruction syndrome (DIOS), a condition unique to CF in which food cannot be properly moved through the digestive system. DIOS often manifests with a lack of bowel movements, unusual feelings of fullness, and vomiting and/or diarrhea.

Because people with CF often experience frequent bacterial infections, they tend to be treated with a lot of antibiotics. While these medicines can be highly effective at killing infectious bacteria, they also kill many of the normally healthy bacteria that reside in the gut. Routine antibiotic use can lead to atypical growth of gut bacteria, which can contribute to digestive symptoms like flatulence, bloating, nausea, and diarrhea.

Gastroesophageal reflux disease (GERD), a condition where stomach acid flows up into the esophagus — the tube in the throat that leads from the mouth to the stomach — can lead to symptoms like heartburn and abdominal pain.

CF mucus also can build up in and cause damage to the liver. About 10% to 15% of CF patients will develop liver disease, which is most common in children. Signs of liver disease may include an enlarged liver and yellow discoloration of the skin.

Individuals with CF also are at increased risk of gallstones, which are hard deposits of digestive fluid in the gallbladder that can be painful and cause blockages.

Reproductive symptoms

CF can cause issues with the body’s reproductive system, including:

• problems with fertility
• irregular or absent menstrual periods
• frequent yeast infections
• urinary incontinence.

Across sexes, people with CF tend to undergo puberty at a later age than their peers. The disease also may affect a patient’s fertility. Most people with CF don’t experience issues with sexual drive or performance that are directly related to their disease, though some symptoms (e.g., chronic coughing) can cause challenges with sexual intimacy.

CF and the male reproductive system

The vas deferens is the tube that transports sperm from the epididymis — a duct behind the testes — prior to ejaculation. More than 90% of men with CF are born lacking this tube on both sides, a condition referred to as congenital bilateral absence of the vas deferens or CBAVD.

In the minority of men with CF who do have a vas deferens, the thick mucus that characterizes the disorder can still cause reproductive challenges. Specifically, mucus can block the vas deferens, preventing the movement of sperm.

Because of these issues, most men with CF cannot conceive children through sexual intercourse. Nonetheless, sperm production in the testes is normal for most men with the disease. Thus, those who wish to have biological children may use assisted reproductive technologies to do so. Such techniques include surgical sperm retrieval or testicular sperm aspiration, also known as MESA or TESA, followed by in vitro (in the lab) fertilization.

Men with CF wanting to biologically reproduce are advised to consult their urologist to identify the best options for them.

CF and the female reproductive system

Women with CF often have irregular or absent menstrual periods. Many women also report that other CF symptoms tend to worsen at certain points in their menstrual cycle. In particular, respiratory symptoms frequently worsen in the middle of a cycle (around day 14 after a period), which is thought to be related to higher levels of the hormone estrogen at this point in the cycle.

An increased risk of yeast infections (vulvovaginal candidiasis) also has been found for women with the disease. These fungal infections can cause symptoms like itching, irritation, discomfort, and pain. The reasons for this increased risk include the regular use of antibiotics and corticosteroids, as well as the high rates of diabetes among CF patients. Antifungal creams and oral medications are usually effective for clearing these infections.

Many women with CF experience some amount of urinary incontinence, when urine leaks out unintentionally. Chronic coughing, as well as childbirth and other physical stressors, can weaken the muscles of the pelvic floor that control urine flow. Physical therapy and targeted exercises can help to strengthen these muscles and is often helpful for reducing urinary incontinence. Other medical interventions also may be helpful, so it’s advised that individuals experiencing urinary incontinence talk to their healthcare team about potential strategies for management.

While fertility problems are much less common in women with CF in comparison with men with the disease, female patients also can experience issues with fertility. The thickening of cervical mucus can affect the movement of sperm across the cervix, making it more difficult to get pregnant. Inflammation of the cervix also may occur in women with CF.

In addition to the direct effects of thick mucus on the reproductive tract, female CF patients may see their fertility indirectly impacted by other disease symptoms. For example, digestive problems caused by CF can lead to inadequate nutrition, which can, in turn, cause irregular ovulation, affecting the release of eggs from the ovaries.

Although CF can bring about reproductive challenges, women with CF are generally fertile. Options such as assisted reproductive technologies also can help women with cystic fibrosis to have biological children. Ensuring proper nutrition before and during pregnancy is key for the health of both mother and baby.

Cystic fibrosis symptoms in babies

In infants with cystic fibrosis, common signs of the disease include:

• intestinal blockage
• slow growth and difficulty putting on weight
• frequent, greasy, foul-smelling stools
• stomach pain or bloating
• frequent lung infections
• coughing, wheezing, and shortness of breath
• salty skin.

In about 20% of newborns with CF, the first noticeable symptom of the disease is a form of intestinal blockage called meconium ileus. Meconium is the first stool a newborn has, and ileus is a failure of normal gut motility without mechanical obstruction. This blockage, occurring in about 1 in 5 babies with CF, forms due to an excessively thick meconium. Meconium ileus is usually managed with medications administered via enema to clear the blockage, though surgery may be needed in some cases.

Poor growth and difficulty putting on weight, even with a good appetite, is another common early sign of CF that arises due to digestive problems that prevent the baby from getting enough nutrients. Digestive issues also can cause stomach pain, bloating, and stools that are unusually bulky and greasy.

Thick mucus also can build up in the lungs of infants with CF, setting the stage for frequent infections and causing symptoms like coughing and difficulty breathing.

The sweat of CF patients tends to have higher-than-usual salt content, owing to abnormal function or production of the CFTR protein, which normally helps to regulate the movement of salts in the body. Testing for levels of salt, specifically chloride, in sweat can be useful for diagnosing CF and monitoring CFTR protein function in babies and also in adults with CF.

Other symptoms

People with CF are at increased risk of developing bone problems such as osteopenia or osteoporosis, when the bones are weaker than normal. This can result in more easily broken bones. The development of bone problems is influenced by many interconnected factors, including poor nutrition and frequent infections.

Cystic Fibrosis News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.