Kalydeco (Ivacaftor)
CFTR Potentiator for Cystic Fibrosis with Specific Gene Mutations
Quick Facts About Kalydeco
Key Takeaways About Kalydeco
- Mutation-specific therapy: Kalydeco (ivacaftor) only works for patients with specific CFTR gene mutations – genetic testing is required before starting treatment
- Must be taken with fat: Always take Kalydeco with fat-containing food (e.g. eggs, cheese, nuts, avocado) to ensure proper absorption
- Liver monitoring required: Liver function tests (ALT and AST) should be performed before starting treatment and regularly during therapy
- Avoid grapefruit: Grapefruit and grapefruit juice can significantly increase ivacaftor levels, raising the risk of side effects
- Combination therapy: Kalydeco can be used alone (monotherapy) or in combination with tezacaftor/ivacaftor or ivacaftor/tezacaftor/elexacaftor (Trikafta) depending on your CFTR mutation
What Is Kalydeco and What Is It Used For?
Kalydeco (ivacaftor) is a CFTR potentiator used to treat cystic fibrosis (CF) in patients aged 6 years and older with specific mutations in the CFTR gene. It works by helping defective CFTR protein channels open more frequently, thereby improving chloride ion transport across epithelial cell membranes.
Kalydeco contains the active substance ivacaftor, which acts on the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein. The CFTR protein forms a chloride channel on the surface of epithelial cells that enables the movement of chloride ions in and out of cells. In people with cystic fibrosis, mutations in the CFTR gene cause this protein to malfunction, leading to reduced chloride transport and the accumulation of thick, sticky mucus in the lungs, pancreas, and other organs.
Ivacaftor belongs to a class of medications called CFTR potentiators. Unlike CFTR correctors (which help the protein fold correctly and reach the cell surface), ivacaftor works by increasing the time that CFTR channels remain open at the cell surface. This improved channel opening enhances chloride and bicarbonate transport, which helps to hydrate the airway surface liquid and restore mucociliary clearance – the body's natural mechanism for removing mucus and pathogens from the lungs.
Clinical trials have demonstrated that Kalydeco significantly improves lung function as measured by forced expiratory volume in one second (FEV1), reduces pulmonary exacerbations, improves body weight, and lowers sweat chloride concentrations. The STRIVE and ENVISION trials showed improvements in FEV1 of approximately 10 percentage points compared to placebo in patients with the G551D mutation, with sustained benefits over long-term treatment.
Approved Indications
As monotherapy, Kalydeco is indicated for patients aged 6 years and older who weigh at least 25 kg and have cystic fibrosis with one of the following CFTR gating mutations: G551D, G1244E, G1349D, G178R, G551S, S1251N, S1255P, S549N, S549R, or R117H.
In combination with tezacaftor/ivacaftor, Kalydeco is approved for patients aged 6 years and older with CF who are homozygous for the F508del mutation or who are heterozygous for F508del with a residual function (RF) mutation.
In combination with ivacaftor/tezacaftor/elexacaftor (marketed as Trikafta in the US and Kaftrio in Europe), Kalydeco is approved for patients aged 6 years and older with CF who have at least one F508del mutation or another CFTR mutation that is responsive to this combination therapy.
Kalydeco (ivacaftor) was first approved by the FDA in January 2012 and by the EMA in July 2012, making it the first medicine to target the underlying cause of cystic fibrosis rather than merely treating symptoms. This represented a landmark breakthrough in CF treatment and paved the way for subsequent CFTR modulator therapies.
What Should You Know Before Taking Kalydeco?
Before starting Kalydeco, you must have a confirmed CF diagnosis with genetic testing showing a responsive CFTR mutation. Inform your doctor about all medical conditions, especially liver or kidney problems, and all medications you are taking. Liver function tests are required before and during treatment.
Contraindications
You should not take Kalydeco if any of the following apply to you:
- Allergy to ivacaftor or any of the other ingredients in the tablets (including lactose monohydrate, microcrystalline cellulose, hypromellose acetate succinate, croscarmellose sodium, sodium lauryl sulfate, colloidal silicon dioxide, and magnesium stearate)
- Two class I CFTR mutations (mutations known not to produce any CFTR protein) – ivacaftor is not expected to provide benefit in these patients because there is no CFTR protein at the cell surface for ivacaftor to potentiate
Warnings and Precautions
Talk to your doctor or pharmacist before taking Kalydeco if you have or have had any of the following conditions:
- Liver problems: Elevated liver enzymes (ALT and AST) have been observed in patients receiving Kalydeco, both as monotherapy and in combination with tezacaftor/ivacaftor or ivacaftor/tezacaftor/elexacaftor. Your doctor will perform blood tests to check your liver function before starting treatment and at regular intervals during therapy, particularly during the first year. Tell your doctor immediately if you experience pain or discomfort in the upper right abdomen, yellowing of the skin or eyes, loss of appetite, nausea or vomiting, or dark-coloured urine – these may be signs of liver injury.
- Depression and mental health: Depression, including suicidal thoughts and suicidal behaviour, has been reported in patients taking Kalydeco, primarily during combination therapy with ivacaftor/tezacaftor/elexacaftor and usually within the first three months of treatment. Contact your doctor immediately if you or the person taking this medicine experience depressed mood, anxiety, emotional distress, or thoughts of self-harm.
- Kidney disease: Inform your doctor if you have or have had kidney problems, as dose adjustments may be necessary.
- Organ transplant: Kalydeco is not recommended for patients who have undergone organ transplantation due to potential drug interactions with immunosuppressive medications.
- Cataracts: Clouding of the eye lens (cataracts) without any effect on vision has been reported in some children and adolescents treated with Kalydeco. Your doctor may perform eye examinations before and during treatment.
- Hormonal contraceptives: If you use hormonal contraceptives (such as birth control pills), inform your doctor, as you may be more likely to develop a rash when taking Kalydeco in combination with ivacaftor/tezacaftor/elexacaftor.
Your doctor will monitor your liver function with blood tests before starting Kalydeco and periodically during treatment. In patients taking Kalydeco in combination with ivacaftor/tezacaftor/elexacaftor, liver damage and worsening liver function have been reported in individuals with severe liver disease. Worsening of liver function can be serious and liver transplantation may be required.
Use in Children and Adolescents
Kalydeco film-coated tablets (75 mg and 150 mg) are approved for use in children aged 6 years and older. For younger children (aged 1 month to less than 6 years), ivacaftor is available in a granule formulation at lower doses. Do not give this medicine to infants under 1 month of age, as the safety and efficacy of ivacaftor have not been established in this population.
When used in combination with tezacaftor/ivacaftor, Kalydeco is approved for children aged 6 years and older. When used in combination with ivacaftor/tezacaftor/elexacaftor, Kalydeco is approved for children aged 6 years and older (with lower age approval for the granule formulation from age 2).
Pregnancy and Breastfeeding
If you are pregnant or breastfeeding, think you may be pregnant, or are planning to have a baby, ask your doctor for advice before taking Kalydeco. There are limited data on the use of ivacaftor in pregnant women. Animal studies have not shown direct harmful effects on fertility or embryo-foetal development at clinically relevant doses. However, as a precautionary measure, it is preferable to avoid the use of Kalydeco during pregnancy unless your doctor determines that the benefit outweighs any potential risk.
Ivacaftor is excreted in human breast milk. If you plan to breastfeed, consult your doctor before taking Kalydeco. Your doctor will weigh the benefit of breastfeeding for your baby against the benefit of treatment for you and will advise whether to discontinue breastfeeding or to discontinue ivacaftor therapy.
Driving and Operating Machinery
Kalydeco can cause dizziness. If you experience dizziness while taking this medicine, do not drive, ride a bicycle, or operate machinery until the symptom resolves. If dizziness persists, consult your doctor.
How Does Kalydeco Interact with Other Drugs?
Kalydeco (ivacaftor) is metabolised by CYP3A enzymes and can interact with many commonly used medications. Strong CYP3A inhibitors significantly increase ivacaftor levels, while strong CYP3A inducers can reduce its effectiveness. Always tell your doctor about all medicines you are taking.
Ivacaftor is primarily metabolised by the cytochrome P450 3A (CYP3A) enzyme system. Medications that inhibit or induce CYP3A can therefore significantly alter ivacaftor blood levels, potentially leading to increased side effects or reduced efficacy. Additionally, ivacaftor itself may affect the metabolism of certain other drugs, particularly those transported by P-glycoprotein (P-gp) or metabolised by CYP2C9.
Major Interactions
The following drugs have clinically significant interactions with Kalydeco and require dose adjustment or are contraindicated:
| Drug / Class | Effect | Recommendation |
|---|---|---|
| Ketoconazole, itraconazole, posaconazole, vorikonazole (strong CYP3A inhibitors) | Markedly increase ivacaftor levels | Reduce Kalydeco dose; close monitoring required |
| Fluconazole, erythromycin, clarithromycin (moderate CYP3A inhibitors) | Moderately increase ivacaftor levels | Dose reduction may be needed; consult your doctor |
| Rifampicin, rifabutin (strong CYP3A inducers) | Substantially reduce ivacaftor levels, potentially eliminating therapeutic benefit | Co-administration not recommended |
| Carbamazepine, phenobarbital, phenytoin (anticonvulsants / CYP3A inducers) | Significantly reduce ivacaftor levels | Co-administration not recommended |
| St. John’s Wort (herbal CYP3A inducer) | Reduces ivacaftor levels unpredictably | Avoid concurrent use |
Other Notable Interactions
Kalydeco may also interact with the following medications. Your doctor may need to adjust your dose or monitor you more closely:
| Drug / Class | Effect | Recommendation |
|---|---|---|
| Ciclosporin, everolimus, sirolimus, tacrolimus (immunosuppressants) | Ivacaftor may increase levels of these drugs | Monitor drug levels; dose adjustment may be needed |
| Digoxin (cardiac glycoside) | Ivacaftor may increase digoxin levels via P-gp inhibition | Monitor digoxin levels closely |
| Warfarin (anticoagulant) | Ivacaftor may affect warfarin metabolism via CYP2C9 | Monitor INR more frequently |
| Glimepiride, glipizide (diabetes medications) | Ivacaftor may increase levels of these drugs | Monitor blood glucose; adjust dose as needed |
| Verapamil (calcium channel blocker) | May increase ivacaftor levels (moderate CYP3A inhibitor) | Monitor for increased side effects |
Avoid food and drinks containing grapefruit during treatment with Kalydeco. Grapefruit contains compounds (furanocoumarins) that inhibit CYP3A enzymes in the gut, which can increase ivacaftor blood levels and raise the risk of side effects. Seville oranges (bitter oranges) should also be avoided for the same reason. Other citrus fruits such as regular oranges, lemons, and limes are safe to consume.
What Is the Correct Dosage of Kalydeco?
The standard adult dose of Kalydeco as monotherapy is 150 mg taken orally every 12 hours with fat-containing food. When used in combination therapy, the evening dose of Kalydeco varies by age and weight. Your doctor will determine the correct dose based on your treatment regimen, age, weight, and liver function.
Always take Kalydeco exactly as your doctor has prescribed. Tablets should be swallowed whole – do not break, crush, chew, or dissolve them. Each dose must be taken with fat-containing food to ensure adequate absorption. The morning and evening doses should be taken approximately 12 hours apart.
Adults and Adolescents (12 Years and Older)
| Treatment Regimen | Morning Dose | Evening Dose |
|---|---|---|
| Kalydeco monotherapy | Kalydeco 150 mg | Kalydeco 150 mg |
| With tezacaftor/ivacaftor | Tezacaftor 100 mg / ivacaftor 150 mg | Kalydeco 150 mg |
| With ivacaftor/tezacaftor/elexacaftor | 2 tablets of ivacaftor 75 mg / tezacaftor 50 mg / elexacaftor 100 mg | Kalydeco 150 mg |
Children (6 to <12 Years)
| Treatment Regimen | Weight | Morning Dose | Evening Dose |
|---|---|---|---|
| Kalydeco monotherapy | ≥25 kg | Kalydeco 150 mg | Kalydeco 150 mg |
| With tezacaftor/ivacaftor | <30 kg | Tezacaftor 50 mg / ivacaftor 75 mg | Kalydeco 75 mg |
| With tezacaftor/ivacaftor | ≥30 kg | Tezacaftor 100 mg / ivacaftor 150 mg | Kalydeco 150 mg |
| With ivacaftor/tezacaftor/elexacaftor | <30 kg | 2 tablets of ivacaftor 37.5 mg / tezacaftor 25 mg / elexacaftor 50 mg | Kalydeco 75 mg |
| With ivacaftor/tezacaftor/elexacaftor | ≥30 kg | 2 tablets of ivacaftor 75 mg / tezacaftor 50 mg / elexacaftor 100 mg | Kalydeco 150 mg |
Dose Adjustment for Liver Impairment
If you have moderate or severe liver impairment, your doctor may need to reduce the dose of Kalydeco because your liver does not clear the medicine as quickly as in patients with normal liver function. Patients with mild liver impairment (Child-Pugh Class A) do not typically require dose adjustment. Patients with moderate impairment (Child-Pugh Class B) should take the dose with caution, and patients with severe impairment (Child-Pugh Class C) should use Kalydeco only if the benefit outweighs the risk, at a significantly reduced dose.
Fat-Containing Food Requirement
Kalydeco must always be taken with fat-containing food to ensure adequate drug absorption. Clinical studies have shown that taking ivacaftor with a high-fat meal increases its absorption by approximately 2–4 fold compared to fasting conditions. Examples of appropriate fat-containing foods and snacks include:
- Eggs, butter, cheese, and whole-milk products (including yoghurt)
- Meat and oily fish
- Avocado, hummus, and soy-based products such as tofu
- Nuts, nut butters, and nutrition bars or drinks that contain fat
- Chocolate and foods prepared with oil
Missed Dose
If you miss a dose of Kalydeco and fewer than 6 hours have passed since your scheduled dose time, take it as soon as you remember with fat-containing food. If more than 6 hours have passed, skip the missed dose and take the next dose at your usual scheduled time. Do not take a double dose to make up for a forgotten dose.
Overdose
If you take more Kalydeco than prescribed, you may experience side effects including those listed in the side effects section. In the event of an overdose, seek medical advice or contact your local poison control centre immediately. Take the medicine packaging with you to help the healthcare team identify what you have taken. There is no specific antidote for ivacaftor overdose; treatment is supportive and symptomatic.
What Are the Side Effects of Kalydeco?
Like all medicines, Kalydeco can cause side effects, although not everyone gets them. The most common side effects include upper respiratory tract infections, headache, dizziness, diarrhoea, abdominal pain, rash, and elevated liver enzymes. Serious side effects include liver injury and depression.
The side effect profile of Kalydeco varies depending on whether it is used as monotherapy or in combination with other CFTR modulators. Liver enzyme elevations are an important safety concern that requires regular monitoring. The following side effects have been reported with Kalydeco (alone or in combination therapy):
Very Common
- Upper respiratory tract infection (cold), including sore throat and nasal congestion
- Headache
- Dizziness
- Diarrhoea
- Abdominal pain (stomach pain)
- Changes in the type of bacteria in sputum (respiratory secretions)
- Elevated liver enzymes (sign of liver stress)
- Rash
Common
- Runny nose (rhinorrhoea)
- Ear pain or ear discomfort
- Tinnitus (ringing in the ears)
- Redness inside the ear
- Inner ear disorder (vertigo – sensation of spinning)
- Sinus congestion (blocked sinuses)
- Throat redness (pharyngeal erythema)
- Breast mass (lump in the breast)
- Nausea
- Influenza (flu)
- Low blood sugar (hypoglycaemia)
- Abnormal breathing (dyspnoea or shortness of breath)
- Flatulence (gas)
- Acne
- Skin itching (pruritus)
- Elevated creatine phosphokinase in blood tests (a marker of muscle breakdown)
Uncommon
- Ear congestion (blocked feeling in the ears)
- Breast inflammation (mastitis)
- Breast enlargement in males (gynaecomastia)
- Nipple changes or nipple pain
- Wheezing
- Elevated blood pressure (hypertension)
Reported (Frequency Not Known)
- Liver damage (hepatic injury)
- Increased bilirubin levels (liver blood test)
- Depression, including suicidal ideation (primarily with combination therapy)
Contact your doctor immediately if you experience: pain or discomfort in the upper right abdomen, yellowing of the skin or whites of the eyes, loss of appetite, nausea or vomiting, dark urine (possible signs of liver problems), or symptoms of depression including persistent low mood, anxiety, or thoughts of self-harm.
Children and adolescents: The side effects observed in children and adolescents are similar to those seen in adults. However, elevated liver enzymes are more common in younger children. Your child's doctor will perform regular blood tests to monitor liver function throughout treatment.
If you experience any side effects, talk to your doctor or pharmacist. This includes any possible side effects not listed above. You can also report suspected side effects to your national pharmacovigilance authority (such as the FDA MedWatch programme in the US, the Yellow Card Scheme in the UK, or EudraVigilance in the EU) to help monitor the ongoing safety of this medicine.
How Should You Store Kalydeco?
Store Kalydeco at room temperature, out of the sight and reach of children. No special storage conditions are required. Do not use the tablets after the expiry date printed on the packaging.
Keep this medicine out of the sight and reach of children. Do not use Kalydeco after the expiry date stated on the carton, blister, or bottle label after “EXP.” The expiry date refers to the last day of the stated month. No special storage conditions are required for Kalydeco film-coated tablets.
Do not throw away medicines via wastewater or household waste. Ask your pharmacist how to dispose of medicines you no longer use. These measures help to protect the environment and ensure that unused medications do not pose a risk to others.
What Does Kalydeco Contain?
Kalydeco film-coated tablets contain the active substance ivacaftor (75 mg or 150 mg per tablet). The tablets also contain inactive ingredients including lactose monohydrate and sodium (in very small amounts).
Active Substance
Each Kalydeco 75 mg film-coated tablet contains 75 mg of ivacaftor. Each Kalydeco 150 mg film-coated tablet contains 150 mg of ivacaftor.
Inactive Ingredients (Excipients)
The tablet core contains: microcrystalline cellulose, lactose monohydrate, hypromellose acetate succinate, croscarmellose sodium, sodium lauryl sulfate (E487), colloidal anhydrous silicon dioxide, and magnesium stearate.
The film coating contains: polyvinyl alcohol, titanium dioxide (E171), macrogol (PEG 3350), talc, indigo carmine aluminium lake (E132), and carnauba wax.
The printing ink contains: shellac, black iron oxide (E172), propylene glycol (E1520), and concentrated ammonia solution.
Kalydeco contains lactose. If you have been told by your doctor that you have an intolerance to some sugars, contact your doctor before taking this medicine. Kalydeco contains less than 1 mmol (23 mg) sodium per dose, meaning it is essentially “sodium-free.”
Tablet Appearance and Pack Sizes
Kalydeco 75 mg tablets are light blue, capsule-shaped (12.7 mm × 6.8 mm), and imprinted with “V 75” in black ink on one side. Available in blister packs of 28 tablets.
Kalydeco 150 mg tablets are light blue, capsule-shaped (16.5 mm × 8.4 mm), and imprinted with “V 150” in black ink on one side. Available in blister packs of 28 or 56 tablets, or bottles of 56 tablets.
Frequently Asked Questions
Kalydeco (ivacaftor) is used to treat cystic fibrosis (CF) in patients aged 6 years and older who have specific mutations in the CFTR gene. It can be used as monotherapy for gating mutations such as G551D, G1244E, G1349D, G178R, G551S, S1251N, S1255P, S549N, S549R, and R117H. It is also used in combination with tezacaftor/ivacaftor or ivacaftor/tezacaftor/elexacaftor (Trikafta/Kaftrio) for patients with F508del and other responsive mutations.
The most common side effects of Kalydeco include upper respiratory tract infections (common cold, sore throat, nasal congestion), headache, dizziness, diarrhoea, abdominal pain, rash, and elevated liver enzymes. Most side effects are mild to moderate and manageable with routine medical care. Liver function should be monitored regularly throughout treatment.
Yes, Kalydeco must be taken with fat-containing food to ensure proper absorption. Taking ivacaftor with a high-fat meal increases absorption by approximately 2–4 fold compared to fasting. Suitable fat-containing foods include eggs, butter, cheese, whole milk and yoghurt, meat, oily fish, avocado, hummus, tofu, nuts, chocolate, and foods cooked in oil. Taking Kalydeco without fat significantly reduces its effectiveness.
No. You should avoid grapefruit and grapefruit juice while taking Kalydeco. Grapefruit contains furanocoumarins that inhibit the CYP3A enzymes responsible for metabolising ivacaftor. This can increase ivacaftor levels in your blood unpredictably, raising the risk of side effects. Seville (bitter) oranges should also be avoided. Other citrus fruits such as regular oranges, lemons, and limes are safe to consume.
Kalydeco works by potentiating (enhancing) the function of the CFTR protein at the cell surface. In cystic fibrosis, mutations in the CFTR gene cause the protein to malfunction, resulting in impaired chloride ion transport and the buildup of thick, sticky mucus. Ivacaftor increases the time that defective CFTR channels remain open, restoring chloride and bicarbonate flow across epithelial cells. This improves airway surface hydration, enhances mucociliary clearance, and leads to measurable improvements in lung function (FEV1), body weight, and sweat chloride levels.
Before starting Kalydeco, you must have CFTR genotyping – a genetic test that identifies the specific mutations in your CFTR gene. Kalydeco as monotherapy is approved for specific gating mutations including G551D, G1244E, G1349D, G178R, G551S, S1251N, S1255P, S549N, S549R, and R117H. In combination therapy, it is also used for patients with F508del and other responsive mutations. Your CF specialist will interpret your genetic test results and determine the appropriate treatment.
References
This article is based on the following international medical guidelines and peer-reviewed sources. All medical claims have evidence level 1A, the highest quality of evidence based on systematic reviews of randomised controlled trials.
- Ramsey BW, Davies J, McElvaney NG, et al. A CFTR potentiator in patients with cystic fibrosis and the G551D mutation (STRIVE study). New England Journal of Medicine. 2011;365(18):1663–1672. doi:10.1056/NEJMoa1105185
- Davies JC, Wainwright CE, Canny GJ, et al. Efficacy and safety of ivacaftor in patients aged 6 to 11 years with cystic fibrosis with a G551D mutation (ENVISION study). American Journal of Respiratory and Critical Care Medicine. 2013;187(11):1219–1225.
- European Medicines Agency (EMA). Kalydeco (ivacaftor) – Summary of Product Characteristics. EMA product information database. Updated October 2025.
- U.S. Food and Drug Administration (FDA). Kalydeco (ivacaftor) – Prescribing Information. FDA drugs database. Accessed January 2026.
- Cystic Fibrosis Foundation. CFTR Modulator Therapies. CFF Clinical Care Guidelines. Updated 2025.
- World Health Organization (WHO). WHO Model List of Essential Medicines – 23rd list. Geneva: WHO; 2023.
- Middleton PG, Mall MA, Drevinek P, et al. Elexacaftor–Tezacaftor–Ivacaftor for Cystic Fibrosis with a Single Phe508del Allele. New England Journal of Medicine. 2019;381(19):1809–1819. doi:10.1056/NEJMoa1908639
- British National Formulary (BNF). Ivacaftor. NICE BNF monograph. Accessed January 2026.
Editorial Team
This article has been written and reviewed by the iMedic Medical Editorial Team, a group of licensed specialist physicians with expertise in pulmonology, clinical pharmacology, and rare diseases including cystic fibrosis.
Medical Writers
Board-certified physicians specialising in pulmonary medicine and clinical pharmacology with documented academic and clinical experience in cystic fibrosis care.
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Independent review board ensuring clinical accuracy, adherence to international guidelines (EMA, FDA, CFF, WHO), and evidence level 1A standards.
All content follows the GRADE evidence framework and is reviewed against current international guidelines. We have no commercial funding or pharmaceutical sponsorship. For more information, see our editorial standards and medical team pages.