You are using an outdated browser. For a faster, safer browsing experience, upgrade for free today.

Symptoms of Cystic Fibrosis

The occurrence and severity of symptoms of cystic fibrosis may vary according to each patient and each age group. The symptoms also tend to vary according to patients' adherence to the treatment of cystic fibrosis. The chance that some symptoms cease or become milder increases as adherence to treatment improves. 

The respiratory, digestive, and reproductive systems are usually the most affected by the buildup of thick mucus in cystic fibrosis. Therefore, they are the most compromised by the disease.

These are the most common symptoms of cystic fibrosis:

  • poor growth, low weight gain, vitamin deficiency, and malnutrition;
  • abnormally large, fatty, foul-smelling stools;
  • frequent pneumonia and bronchitis;
  • chronic sinusitis;
  • chronic cough with sputum and sometimes blood;
  • salty-tasting skin resulting from excessive salt in sweat;
  • appearance of nasal polyps (inflamed tissue inside the nose);
  • respiratory infections often caused by Pseudomonas aeruginosa (Pa), Staphylococcus aureus, or Haemophilus influenzae.


Other possible consequences of cystic fibrosis include:

  • obstructive azoospermia in men (obstruction of vas deferens, through which semen passes) and obstruction of cervical canal in women, both because of excessive mucus. In both cases, reproduction is affected;
  • low bone density and osteoporosis;
  • enlargement of the tips of fingers and toes (digital clubbing);
  • diabetes.


The main cystic fibrosis signs and symptoms in each of the human body systems are described below:

  • Respiratory system: Thick mucus may cause a variety of symptoms in the airways, from the nose to the lungs. Without adequate treatment, patients with cystic fibrosis have chronic cough, excessive production of sputum, and shortness of breath. In advanced stages, or when the treatment is not effective, changes in lung architecture may make breathing hard, cause episodes of coughing up blood, and reduce the level of oxygen in the body, among others. In addition to Pa, other common bacteria in the airways are Staphylococcus aureus and Haemophilus influenzae. Excessive mucus and infections in the paranasal sinus region may cause headaches and respiratory problems, chronic sinusitis, and nasal polyps (excessive growth inside the nasal tissue), which contribute to respiratory difficulties. 
  • Digestive system: Thick mucus may also block pancreatic pathways, preventing enzymes produced by the pancreas from reaching the intestine. Thus, the body of the patient with cystic fibrosis do not absorb enough amounts of fat, which may cause vitamin deficiency and malnutrition, abnormally large stools, flatulence, abdominal swelling, severe constipation, diarrhea, and abdominal pain and discomfort. In children, growth and weight gain are deficient.
  • Reproductive system: Men with cystic fibrosis are naturally infertile because of obstructive azoospermia. Nevertheless, advances in medicine have provided some alternatives. For women, becoming pregnant may be difficult because of the excessive mucus blocking cervical canals in the uterus, or because of other complications of cystic fibrosis, such as malnutrition. It should be noted that the child of a person with cystic fibrosis has a greater chance – at least 50% – to also be born with the disease because it is a genetic condition.


What is mucus and what is its function in the organism?

To understand the symptoms of cystic fibrosis, we need to understand the function of mucus in the body. Mucus is a substance produced by exocrine glands, which are present in some organs, with the purpose of keeping these organs moist and free from infection.

In people with cystic fibrosis, the mucus becomes thick and builds up in some organs and pathways of the body, favoring the occurrence of inflammations and infections.