What Is Symdeko? Uses, Dosage, and What You Need to Know in 2026

Symdeko is a prescription medication used to treat cystic fibrosis (CF) — a rare, life-shortening genetic disease that causes thick, sticky mucus to build up in the lungs, pancreas, and other organs. Unlike older CF treatments that only address symptoms, Symdeko targets the underlying cause of the disease. Here's everything you need to know about what Symdeko is, how it works, who it's for, and how to take it.

What Is Symdeko?

Symdeko is the brand name for a combination of two active pharmaceutical ingredients: tezacaftor and ivacaftor. It is manufactured by Vertex Pharmaceuticals and belongs to a class of drugs called CFTR (cystic fibrosis transmembrane conductance regulator) modulators. CFTR modulators are a breakthrough class of medications that treat the genetic defect causing CF — not just its symptoms.

Symdeko was first approved by the FDA in February 2018 for patients ages 12 and older. In 2020, its FDA approval was expanded to include children ages 6 to 11. In Europe and other international markets, Symdeko is marketed as Symkevi.

What Does Symdeko Treat?

Symdeko is indicated for the treatment of cystic fibrosis in patients ages 6 and older who have:

Two copies of the F508del mutation (the most common CF-causing mutation, present in roughly half of all CF patients), OR

At least one mutation in the CFTR gene that is responsive to tezacaftor/ivacaftor — a list of 154 eligible mutations is included in the Symdeko label

CF is caused by mutations in the CFTR gene that result in a defective or absent CFTR protein. This leads to the buildup of thick, sticky mucus that blocks the lungs, disrupts digestion, and causes damage throughout the body. Symdeko helps correct CFTR protein function so that chloride and water can flow more normally through cell membranes.

How Effective Is Symdeko?

In the pivotal EVOLVE clinical trial (475 patients with two F508del mutations), Symdeko improved percent-predicted FEV1 (ppFEV1 — a key measure of lung function) by approximately 4 percentage points compared to placebo. The trial also showed that Symdeko reduced acute pulmonary exacerbations by 35% compared to placebo and improved quality of life measures.

While Symdeko is effective, newer CFTR modulators — particularly Trikafta (elexacaftor/tezacaftor/ivacaftor) and Alyftrek (vanzacaftor/tezacaftor/deutivacaftor) — have demonstrated greater efficacy. Trikafta improves ppFEV1 by approximately 10 percentage points more than Symdeko in head-to-head trials. For patients eligible for both, CF specialists often recommend Trikafta or Alyftrek as the first-line choice.

Symdeko Dosage: How to Take It

Symdeko comes in a co-packaged format with two different tablets in weekly wallet blister packs:

For patients ages 12 and older:

Morning dose: One tezacaftor 100 mg / ivacaftor 150 mg tablet (yellow, marked "V100")

Evening dose (12 hours later): One ivacaftor 150 mg tablet (light blue, marked "V150")

For patients ages 6 to 11:

Morning dose: One tezacaftor 50 mg / ivacaftor 75 mg tablet (white, marked "V50")

Evening dose (12 hours later): One ivacaftor 75 mg tablet (light blue, marked "V75")

Key administration rules:

Always take Symdeko with fat-containing food — such as eggs, avocado, peanut butter, whole milk, cheese, or yogurt — to enhance absorption

Avoid grapefruit and Seville oranges (orange marmalade) — these inhibit the enzyme that metabolizes Symdeko, which can increase drug levels in the blood

Swallow tablets whole — do not crush or chew

If you miss a dose within 6 hours, take it with food as soon as possible; if more than 6 hours have passed, skip the missed dose and resume normal schedule

What Is Symdeko Not Approved For?

Symdeko is approved only for CF patients with specific eligible CFTR mutations. It is not appropriate for CF patients whose mutations do not respond to tezacaftor or ivacaftor. It is not approved for patients under age 6. If your genotype is unknown, your doctor will order genetic testing before prescribing Symdeko.

Is Symdeko a Controlled Substance?

No. Symdeko is not a controlled substance and is not scheduled by the DEA. It does not have addiction or abuse potential. However, it is a prescription medication that requires a prescription from a licensed healthcare provider.

Where Can I Fill My Symdeko Prescription?

Symdeko is only available through specialty pharmacies — it is not stocked at retail locations. Your insurance plan designates which specialty pharmacy you must use. medfinder can help you find which pharmacies can fill your prescription by calling them on your behalf and texting you the results.

For information about how to manage the cost of Symdeko, see: How to Save Money on Symdeko in 2026.