Kalydeco (Ivacaftor) - Oral

What Is Kalydeco?

Kalydeco (ivacaftor) is a prescription medication used to treat a specific type of cystic fibrosis (CF), a genetic disease that causes problems with breathing, digestion, and reproduction. It is in the class of drugs called cystic fibrosis transmembrane conductance regulator (CFTR) potentiators.

Mutations in the CFTR gene result in defective cystic fibrosis transmembrane conductance regulator proteins, which in turn cause CF. This medication is the first of the drugs approved by the Food and Drug Administration (FDA) that targets the G551D mutation. It improves the function of a protein in the body that helps decrease the build-up of thick mucus in the lungs and improve CF symptoms.

Kalydeco is available as an oral tablet or as granules.

Drug Facts

Generic Name:  Ivacaftor

Brand Name(s): Kalydeco

Drug Availability: Prescription

Therapeutic Classification: CFTR potentiator

Available Generically: No

Controlled Substance: N/A

Administration Route: Oral

Active Ingredient: Ivacaftor

Dosage Form(s): Tablet and granules

What Is Kalydeco Used For?

Kalydeco is used to treat CF in people aged 4 months and older with the G551D mutation in the CFTR gene. If the person's genotype is unknown, an FDA-cleared CF mutation test should be used to detect the presence of a G551D CFTR mutation. 

This medication is not recommended for use in people younger than 4 months. Only people with a specific genetic makeup should use Kalydeco. Your healthcare provider may order a blood test to help decide if this medication is right for you.

Kalydeco (Ivacaftor) Drug Information - Illustration by Zoe Hansen

Verywell / Zoe Hansen

How to Take Kalydeco

Always follow the instructions carefully and take this medication exactly as prescribed by your healthcare provider. Ask your healthcare provider if you need help understanding anything.

Kalydeco comes as a tablet and as granules to take by mouth. It is usually prescribed twice a day, with the dosages taken 12 hours apart. Take this medicine with rich fatty foods such as butter, cheese pizza, eggs, peanut butter or other nut butters, or whole-milk dairy products. 

If taking oral granules, shake your packet gently before opening it. Open one packet and pour the contents in a teaspoon (5 milliliters) at room temperature. Mix the granules with soft food or liquid such as applesauce, pureed fruits or vegetables, yogurt, water, breast milk, infant baby formula, milk, or juice. After mixing, take this medicine within one hour. Make sure all of the medication is taken.

Take your doses at around the same time every day as directed by your healthcare provider. Do not take more, less, more often, or longer than prescribed to reduce side effects. Don't eat grapefruit or Seville oranges or drink their juice while taking Kalydeco. Using these products with Kalydeco increases the absorption of the medicine in your blood and can increase side effects.

Ivacaftor controls cystic fibrosis but does not cure it. Continue to take your doses even if you feel well. Do not stop taking ivacaftor without talking to your healthcare provider.


Keep Kalydeco in the container it came in, tightly closed, away from heat and moisture. Keep all medications away from children and pets to avoid poisoning.

Don't keep expired or unneeded medications with you. Don't discard your medicines down the toilet or throw them in the trashcan. The best way to discard your medication is through a medicine take-back program. Contact your local waste management company or talk to your pharmacist to learn about medicine take-back programs in your community.

How Long Does Kalydeco Take to Work?

After taking Kalydeco (ivacaftor) with a high-fat-containing food, the concentration of the drug peaks in your body at around four hours.

What Are the Side Effects of Kalydeco?

This is not a complete list of side effects, and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your pharmacist or a healthcare provider. You may report side effects to the FDA at fda.gov/medwatch or 800-FDA-1088.

Common Side Effects

Some common side effects are:

  • Diarrhea
  • Dizziness
  • Headache
  • Joint pain
  • Rash
  • Symptoms of an infection such as fever, sore throat, or runny nose.

Contact your healthcare provider if any of these worsens or does not go away.

Severe Side Effects

Some side effects can be severe and need medical attention, such as:

Contact your healthcare provider or seek medical help if you have any worsening symptoms.

Report Side Effects

Kalydeco may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication. If you experience a serious side effect, you or your healthcare provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or phone (800-332-1088).


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The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage forms (granules, tablets):
    • For cystic fibrosis:
      • Adults and children 6 years of age and older—150 milligrams (mg) every 12 hours, taken with fat-containing food.
      • Children 6 months to younger than 6 years of age and weighing 14 kilograms (kg) or more—Dose is based on body weight and must be determined by your doctor. The dose is usually one 75 mg packet every 12 hours, taken with fat-containing food.
      • Children 6 months to younger than 6 years of age and weighing 7 to less than 14 kg—Dose is based on body weight and must be determined by your doctor. The dose is usually one 50 mg packet every 12 hours, taken with fat-containing food.
      • Children 6 months to younger than 6 years of age and weighing 5 to less than 7 kg—Dose is based on body weight and must be determined by your doctor. The dose is usually one 25 mg packet every 12 hours, taken with fat-containing food.
      • Children 4 months to younger than 6 months of age and weighing 5 kg or more—Dose is based on body weight and must be determined by your doctor. The dose is usually one 25 mg packet every 12 hours, taken with fat-containing food.
      • Children 4 months to younger than 6 years of age or weighing less than 5 kg—Use and dose must be determined by your doctor.
      • Children younger than 4 months of age—Use is not recommended.


Changes in Kalydeco (ivacaftor) may need to be made when it's used in specific populations.

There is limited data on the use of Kalydeco in pregnant or breastfeeding women, the presence of ivacaftor in human milk, or its effects on the breastfed infant or milk production. Until more data is available, your child's healthcare provider will likely monitor your infant's bilirubin and liver enzymes if you take ivacaftor while breastfeeding. Pregnant and breastfeeding women must only be given Kalydeco if the benefits outweigh the adverse effects.

The safety and effectiveness of ivacaftor in people with cystic fibrosis younger than 4 months have not been established. The use of the drug in children under the age of 4 months is not recommended.

Clinical trials of ivacaftor have not been able to include enough numbers of people aged 65 years and over. It is unknown whether older people respond differently from younger people, so caution is advised.

A change in the dose is not necessary for people aged 6 months or older with mild to moderate liver (hepatic) impairment. However, a dose reduction and cautious use are required in people with severe liver impairment.

Ivacaftor has not been studied in people with mild, moderate, or severe kidney (renal) impairment or end-stage renal disease. Therefore, a dose reduction is not required in people with mild to moderate renal impairment; however, caution is recommended in those with severe renal impairment (creatinine clearance <30 milliliters/minute) or end-stage renal disease.

Missed Dose

Take your dose if you remember to take the missed dose within six hours of your regular scheduled time. However, skip the missed dose if more than six hours have passed after the scheduled time. Continue to take the following doses at your regular time. Don't take a double dose to make up for the missed one.

Overdose: What Happens If I Take Too Much Kalydeco?

Symptoms of overdose may include dizziness and diarrhea.

What Happens If I Take Too Much Kalydeco?

If you think you or someone else may have overdosed on Kalydeco, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking Kalydeco, call 911 immediately.


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It is very important that your doctor check your or your child's progress at regular visits to make sure that this medicine is working properly. Blood tests will be needed to check for unwanted effects.

Check with your doctor right away if you or your child have pain or tenderness in the upper stomach, pale stools, dark urine, loss of appetite, nausea, unusual tiredness or weakness, or yellow eyes or skin. These could be symptoms of a serious liver problem.

This medicine may make you dizzy. Do not drive or do anything else that could be dangerous until you know how this medicine affects you.

Check with your doctor immediately if blurred vision, difficulty in reading, or any other change in vision occurs during or after treatment. Your doctor may want your eyes be checked by an ophthalmologist (eye doctor).

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal (eg, St. John's wort) or vitamin supplements.

What Are The Reasons I Shouldn't Take Kalydeco?

Consult your healthcare provider before taking Kalydeco in:

  • Children under the age of 4 months
  • Eye or vision problems such as cataracts
  • Severe kidney disease such as end-stage renal disease
  • Liver disease, moderate or severe 

What Other Medications Interact With Kalydeco?

Ivacaftor may interact with some drugs when given together. Changes in your dosage may be needed if you're taking these medications:

Antibiotics like:

  • Biaxin (clarithromycin)
  • Erythrocin (erythromycin)
  • Ketek (telithromycin)

Antifungals like:

  • Diflucan (fluconazole)
  • Sporanox (itraconazole)
  • Nizoral (ketoconazole)
  • Noxafil (posaconazole)
  • Vfend (voriconazole)

Antiseizure drugs like:

  • Tegretol (carbamazepine)
  • Phenobarbital
  • Phenytek (phenytoin)

Other drugs:

  • Midazolam
  • Mycobutin (rifabutin)
  • Rifamate (rifampin)
  • Amaryl (glimepiride)
  • Glucotrol (glipizide)
  • Neoral (cyclosporine)
  • Lanoxin (digoxin
  • Warfarin
  • Astagraf (tacrolimus)
  • St. John's wort

Do not take grapefruit or Seville oranges or drink their juice before taking Kalydeco.

This may not be a complete list of drugs. Discuss with your healthcare provider about the prescription, non-prescription, supplements, or herbal preparations that you take. 

What Medications Are Similar?

Kalydeco is a "cystic fibrosis transmembrane conductance regulator (CFTR) modulator." CTFR modulators have been developed relatively recently. They improve the function of CFTR in people with specific gene mutations. However, each drug is not suitable for everyone and requires the person to undergo genetic testing to identify a CFTR mutation.

The CFTR modulators that are approved for use by the U.S. Food and Drug Administration (FDA) along with Kalydeco are: 

  • Orkambi (lumacaftor + ivacaftor)
  • Symdeko (tezacaftor + ivacaftor) 
  • Trikafta (elexacaftor, tezacaftor, and ivacaftor)

A combination of lumacaftor and ivacaftor is used in people with two copies of the deltaF508del mutation. Orkambi works by changing a protein's shape and helping it work better.

Another combination of tezacaftor and ivacaftor is designed for people with two deltaF508 mutations in people who cannot tolerate Orkambi. 

The combination of elexacaftor, tezacaftor, and ivacaftor is approved for people with an F508del mutation in the CFTR gene. This particular gene mutation is estimated to represent 90% of the cystic fibrosis population.

Other CFTR modifiers are currently in development or clinical trial stage, including two experimental drugs—known as VX-659 and VX-445.

Frequently Asked Questions

  • What is Kalydeco used for?

    Kalydeco is used to treat cystic fibrosis in people with at least one mutation in a specific gene (the cystic fibrosis transmembrane conductance regulator gene).

  • How does Kalydeco work?

    The precise way that Kalydeco works (its "mechanism of action") is unknown. However, ivacaftor is thought to restore the flow of chloride ions in your body. This helps the function of specific proteins in the body, reduces the build-up of thick mucus in the lungs, and improves cystic fibrosis symptoms.

  • What are the side effects of Kalydeco?

    Some common side effects of Kalydeco are headache, upper respiratory tract infection, joint pain, nasal congestion, skin rash and dizziness. These side effects are not very severe and usually do not require medical attention. However, immediately call your healthcare provider if you experience a loss of appetite, pain in your stomach, dark urine, extreme fatigue, unusual bleeding, yellowing of your skin or eyes, or vision changes.

  • What mutations does Kalydeco treat?

    Kalydeco is a relatively new and novel gene-based therapy for treating cystic fibrosis (CF). It is approved for use in people with CF who have at least one G551D mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene.

  • Can Kalydeco make you feel dizzy?

    Kalydeco can make you dizzy. Do not drive, cycle or use machines unless you know how this medicine affects you.

  • What dietary precautions should I take while taking Kalydeco?

    Don't eat grape fruit juice or Seville orange or use their juice while taking Kalydeco.

How Can I Stay Healthy While Taking Kalydeco?

Cystic fibrosis (CF) is a genetic disease caused by a mutation in a gene that is sometimes fatal. CF can cause lung disease and repeated infections. The treatment burden associated with this condition is significant, time-consuming, and non-curative, meaning the treatment targets the symptoms rather than the cause of the disease. 

Kalydeco is a drug that treats cystic fibrosis CF by targeting specific proteins. You should always take medicine as prescribed. Try to take the drug with a high-fat food. Ivacaftor may increase your aminotransferase levels so your healthcare provider may ask for blood tests. Be sure to do your best to keep your lab work appointments. And check for cataracts in yourself or your child while taking.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Food and Drug Administration. Kalydeco label.

  3. MedlinePlus. Ivacaftor.

  4. Jain R, Taylor-Cousar JL. Fertility, pregnancy and lactation considerations for women with cf in the cftr modulator era. J Pers Med. 2021;11(5):418.  doi:10.3390/jpm11050418.

  5. Hoy SM. Elexacaftor/ivacaftor/tezacaftor: first approval. Drugs. 2019;79(18):2001-2007. doi:10.1007/s40265-019-01233-7