Cystic fibrosis

Symptoms of cystic fibrosis

Cystic fibrosis will usually be detected with a test when your baby’s born.

Treatment to help manage the symptoms will start as soon as possible. If it is not detected, you may see more of these symptoms.

Symptoms usually start in early childhood. The main symptoms are caused by a build-up of mucus in the lungs and the digestive system.


Common symptoms include:

  • coughing
  • wheezing and shortness of breath
  • recurring chest infections: this is because the mucus that builds up in the lungs is an ideal breeding ground for bacteria

Though the lungs are likely to be normal and healthy at birth, repeated lung infections can cause them to become damaged. Infections cause the airways to become inflamed, making them wider than normal. This is called bronchiectasis.

Digestive system

Common symptoms include:

  • difficulty putting on weight and growing
  • pale, greasy poo
  • physical weakness
  • hunger and thirst
  • constipation
  • serious constipation (meconium ileus) in the first few days of life

It’s common for people with cystic fibrosis to have delayed puberty and the condition can also lead to reduced fertility.

People sometimes develop other conditions as a result of cystic fibrosis. This usually happens towards the end of childhood, or in adulthood. These include:

  • diabetes
  • bone disease causing thin, weakened bones
  • liver problems

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Last medically reviewed: September 2016. Due for review: September 2019

This information uses the best available medical evidence and was produced with the support of people living with lung conditions. Find out how we produce our information. If you’d like to see our references get in touch.