Serious and Most Common Side Effects

How the safety of KALYDECO® was assessed in clinical studies

The overall safety profile of KALYDECO is based on pooled data from 3 placebo-controlled trials.

Across these trials, a total of 353 people 6 years of age and older with the G551D mutation (Trials 1 and 2) or 2 copies of the F508del * mutation (Trial 3) in their CFTR gene took KALYDECO or placebo every 12 hours with fat-containing food. Two hundred twenty-one people received KALYDECO and 132 people received placebo.

The safety data from the 3 clinical studies were combined and reviewed together, or "pooled," to arrive at the safety profile for KALYDECO.

In addition, safety was assessed in the following clinical studies:

  • An 8-week, crossover design trial (Trial 4) of 39 patients between the ages of 6 and 57 years with a G1244E, G1349D, G178R, G551S, G970R, S1251N, S1255P, S549N, or S549R mutation in their CFTR gene
  • A 24-week, placebo-controlled trial (Trial 5) of 69 patients age 6 to 68 years with the R117H mutation in their CFTR gene
  • A 24-week, open-label trial (Trial 6) in patients 2 to less than 6 years of age of 34 patients with a G551D or S549N mutation in their CF gene
  • An 8-week, crossover design trial (Trial 7) that included patients between the ages of 12 and 72 years who had one copy of the F508del mutation and a second mutation that is predicted to respond to KALYDECO

The safety profile for Trials 4, 5, 6, and 7 was similar to that observed in Trials 1 and 2.

Remember, this website is for informational purposes only and is not intended to be a substitute for professional medical advice. You should talk to your healthcare provider about the clinical study results and the possible side effects of KALYDECO.

*KALYDECO is not responsive in people with CF with two copies of the F508del mutation (F508del/F508del) in the CF gene.


What are the possible side effects of KALYDECO?

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KALYDECO can cause serious side effects


High liver enzymes in the blood have been reported in patients receiving KALYDECO


Your doctor will do blood tests to check your liver:

  • before you start KALYDECO
  • every 3 months during your first year of taking KALYDECO
  • every year while you are taking KALYDECO

For patients who have had high liver enzymes in the past, the doctor may do blood tests to check the liver more often

Call your doctor right away if you have any of the following symptoms of liver problems:

  • pain or discomfort in the upper right stomach (abdominal) area
  • yellowing of your skin or the white part of your eyes
  • loss of appetite
  • nausea or vomiting
  • or dark, amber-colored urine

Abnormality of the eye lens (cataract) has been noted in some children and adolescents receiving KALYDECO. Your doctor should perform eye examinations prior to and during treatment with KALYDECO to look for cataracts


The most common side effects include

  • headache
  • upper respiratory tract infection (common cold), which includes
    • sore throat
    • nasal or sinus congestion
    • runny nose
  • stomach (abdominal) pain
  • diarrhea
  • rash
  • nausea
  • dizziness

Tell your doctor if you have any side effect that bothers you or that does not go away. These are not all the possible side effects of KALYDECO. For more information, ask your doctor or pharmacist.

What is KALYDECO® (ivacaftor)?

KALYDECO is a prescription medicine used for the treatment of cystic fibrosis (CF) in patients age 2 years and older who have at least one mutation in their CF gene that is responsive to KALYDECO.

Talk to your doctor to learn if you have an indicated CF gene mutation.

It is not known if KALYDECO is safe and effective in children under 2 years of age.

Important Safety Information

Who should not take KALYDECO?

Do not take KALYDECO if you take certain medicines or herbal supplements such as: the antibiotics rifampin (Rifamate®, Rifater®) or rifabutin (Mycobutin®); seizure medications such as phenobarbital, carbamazepine (Tegretol®, Carbatrol®, Equetro®) or phenytoin (Dilantin®, Phenytek®); or St. John’s wort.

Talk to your doctor before taking KALYDECO if you take any of these medicines or supplements.