If you have kidney disease or you are a child with rash, then you should avoid using Kalydeco
Ivacaftor may rarely cause serious liver disease. Get medical help right away if you have any symptoms of liver damage, including: dark urine, persistent nausea/vomiting/loss of appetite, stomach/abdominal pain, yellowing eyes/skin.
Ivacaftor can commonly cause a rash that is usually not serious. However, you may not be able to tell it apart from a rare rash that could be a sign of a severe reaction. Therefore, tell your doctor right away if you develop any rash.