Read the Patient Information Leaflet if available from your pharmacist before you start taking ivacaftor and each time you get a refill. If you have any questions, ask your doctor or pharmacist.

Take this medication by mouth as directed by your doctor, usually twice daily (every 12 hours).

If you are taking the tablet form of this medication, take this medication with fat-containing foods (such as eggs, butter, peanut butter, cheese). The manufacturer directs to swallow this medication whole. However, many similar drugs (immediate-release tablets) can be split/crushed. Follow your doctor's directions on how to take this medication.

If you are taking the granules form of this medication, gently shake the packet before use. Empty the packet into a small cup with 1 teaspoonful (5 milliliters) of soft food (such as yogurt, applesauce) or liquid (such as water, milk, infant formula). The soft food or liquid should be at or below room temperature. Mix the granules with the soft food or liquid and take the entire mixture within 1 hour of mixing. Eat a fat-containing food either right before or just after taking the mixture.

The dosage is based on your medical condition, age, weight, response to treatment, and other medications you may be taking. Be sure to tell your doctor and pharmacist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Use this medication regularly to get the most benefit from it. To help you remember, take it at the same time(s) each day.

Avoid eating grapefruit or drinking grapefruit juice while using this medication unless your doctor or pharmacist says you may do so safely. Grapefruit can increase the chance of side effects with this medicine. Ask your doctor or pharmacist for more details.

Tell your doctor if your condition does not improve or if it worsens.