Reviewed on 9/9/2022

What Is Ivacaftor and How Does It Work?

Ivacaftor is a prescription medication used to treat cystic fibrosis in adults and children who are a least 6 months old and weigh at least 11 pounds (5 kilograms). Ivacaftor is for use only in patients with a specific gene mutation related to cystic fibrosis.

  • Ivacaftor is available under various brand names: Kalydeco

What Are Side Effects Associated with Using Ivacaftor?

Common side effects of Ivacaftor include:

Serious side effects of Ivacaftor include:

  • hives, 
  • difficult breathing,
  • swelling of the face, lips, tongue, or throat,
  • severe stomach pain,
  • vision problems, eye pain,
  • low blood sugar--headache, hunger, sweating, irritability, dizziness, nausea, fast heart rate, and feeling anxious or shaky; or
  • liver problems--loss of appetite, stomach pain (upper right side), nausea, vomiting, dark urine, jaundice (yellowing of the skin or eyes).

Rare side effects of Ivacaftor include:

  • none

Seek medical care or call 911 at once if you have the following serious side effects:

  • Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, loss of coordination, feeling unsteady, very stiff muscles, high fever, profuse sweating, or tremors;
  • Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
  • Serious heart symptoms such as fast, irregular, or pounding heartbeats; fluttering in the chest; shortness of breath; sudden dizziness, lightheartedness, or passing out.

This is not a complete list of side effects and other serious side effects or health problems that may occur because of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

What Are Dosages of Ivacaftor?

 Adult and pediatric dosage


  • 150 mg

Oral granules

  • 25 mg/unit dose packet
  • 50 mg/unit dose packet
  • 75 mg/unit dose packet

Cystic fibrosis: 

Adult dosage

  • Oral: Tablet: 150 mg every 12 hours

Pediatric dosage

  • Infants 4 to 6 months weighing above 5 kg: 
    • Oral granules: 25 mg granule packet every 12 hours.
  • Infants above 6 months and Children below 6 years: Oral granules:
    • Weighing between 5 to 7 kg: 25 mg granule packet every 12 hours.
    • Weighing between 7 to 14 kg: 50 mg granule packet every 12 hours.
    • Weighing above 14 kg: 75 mg granule packet every 12 hours.
  • Children above 6 years and Adolescents:
    • Oral tablet: 150 mg every 12 hours.

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”

What Other Drugs Interact with Ivacaftor?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first

  • Ivacaftor has severe interactions with the following drugs:
    • lonafarnib
  • Ivacaftor has serious interactions with at least 43 other drugs.
  • Ivacaftor has moderate interactions with at least 196 other drugs.
  • Iivacaftor has minor interactions with no other drugs.

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all your products. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions or concerns.

What Are Warnings and Precautions for Ivacaftor?


  • Hypersensitivity to Ivacaftor

Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Ivacaftor?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Ivacaftor?”


  • Tell your doctor about all your current medicines and any you start or stop using. Many drugs can interact, and some drugs should not be used together.
  • Avoid driving or hazardous activity until you know how this medicine will affect you. Your reactions could be impaired.
  • Grapefruit and Seville oranges may interact with ivacaftor and lead to unwanted side effects. Avoid the use of grapefruit products and orange marmalades.

Pregnancy and Lactation

  • It is not known whether this medicine will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.


  • It may not be safe to breastfeed while using this medicine. Ask your doctor about any risks.

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