Cystic Fibrosis Symptoms

Cystic fibrosis is a genetic condition that affects the production and flow of mucus in the lungs and digestive system. Symptoms usually manifest within the first year of life, although they can develop later. The symptoms are primarily caused by a thick, sticky mucus clogging up the lung airways and the digestive system. Symptoms vary in intensity and severity from person to person.

Lung and respiratory tract symptoms

Long term persistent cough and wheezing
This is caused by the body’s response to the thick mucus that blocks the airways, which is to try and cough up and eject the obstructing mucus.

Recurrent infections of the chest and lung
Continuous build up of the mucus in the lungs provides a favourable environment for bacterial growth which causes recurrent chest infections and severe complications. Strains of bacteria that commonly infect people with cystic fibrosis include Pseudomonas aeruginosa and Staphlyococcus aureus.

Ear and sinus infections
These infections are also very common and are caused by spread of infection from the respiratory tract. Older children may also develop nasal polyps.

Digestive system symptoms

  • Ducts in the pancreas may become blocked and dysfunctional leading to secondary diabetes
  • A lack of pancreatic enzymes may reduce the breakdown and use of food, leading to large, smelly stools and the passing of unused nutrients and fats.
  • This reduction in absorbed nutrients also leads to malnutrition and reduced growth, which can delay puberty and cause other complications. Adults with cystic fibrosis often do not gain weight.
  • The bile ducts may also become blocked due to cystic fibrosis.

Sweat and skin symptoms

The child’s sweat may be unusually salty, which may be noticed when the child is kissed.

Generalized symptoms

  • Reduced growth and weight gain
  • Diabetes due to a lack of pancreatic hormones such as insulin
  • Bones and joints may become weak due to malnutrition. Older children with cystic fibrosis also develop swollen or painful joints (arthritis) and are at risk of developing osteoporosis.
  • Infertility is a major complication of cystic fibrosis. Malnutrition leads to delayed puberty, hormonal imbalances and infertility. In men, the tubes that carry sperm do not develop normally. In women, the cervical mucus is thicker and more difficult for sperm to penetrate.
  • People with cystic fibrosis may also develop urinary incontinence.

Further Reading

Last Updated: Aug 21, 2023

Dr. Ananya Mandal

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.


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