What the label lists and what reports show
Ivacaftor and tezacaftor side effects
Ivacaftor and tezacaftor's FDA label: “The most common adverse drug reactions to SYMDEKO (occurring in ≥3% of patients) were headache, nausea, sinus congestion, and dizziness.” FAERS holds 5,286 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is infective pulmonary exacerbation of cystic fibrosis (1,182 reports).
- No generic listed
Check it at the source: the ivacaftor and tezacaftor FDA label on DailyMed (effective August 21, 2026); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of SYMDEKO?SYMDEKO can cause serious side effects, including: High liver enzymes in the blood have been reported in people treated with SYMDEKO or treated with ivacaftor alone. Your doctor will do blood tests to check your liver: before you start SYMDEKO every 3 months during your first year of taking SYMDEKO every year while you are taking SYMDEKO Your doctor may do blood tests to check the liver more often if you have had high liver enzymes in your blood in the past. Call your doctor right away if you have any of the following symptoms of liver problems: pain or discomfort in the upper right stomach (abdominal) area yellowing of your skin or the white part of your eyes loss of appetite nausea or vomiting dark, amber-colored urine Serious Allergic Reactions can happen to people who are treated with SYMDEKO. […]
Source: FDA drug label, Vertex Pharmaceuticals Incorporated, effective August 21, 2026 (SPL set 302ae804-37db-44fd-ac2f-3dbdeda9aa4b), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most common adverse drug reactions to SYMDEKO (occurring in ≥3% of patients) were headache, nausea, sinus congestion, and dizziness.
Table 5: Incidence of Adverse Drug Reactions in ≥3% of SYMDEKO-Treated Patients and Greater than Placebo
| Adverse Reactions (Preferred Term) | SYMDEKO N=334 n (%) | Placebo N=343 n (%) |
|---|---|---|
| Headache | 49 (15) | 44 (13) |
| Nausea | 29 (9) | 24 (7) |
| Sinus congestion | 13 (4) | 6 (2) |
| Dizziness | 12 (4) | 8 (2) |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedThe following adverse reactions are discussed in greater detail in other sections of the label: Transaminase Elevations [see Warnings and Precautions (5.1) ] Hypersensitivity Reactions, Including Anaphylaxis [see Warnings and Precautions (5.2) ] Intracranial Hypertension [see Warnings and Precautions (5.3) ] Neuropsychiatric Events, Including Suicidal Thoughts and Behaviors [see Warnings and Precautions (5.4) ] Cataracts [see Warnings and Precautions (5.6) ] The most common adverse drug reactions to SYMDEKO (occurring in ≥3% of patients) were headache, nausea, sinus congestion, and dizziness. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Vertex Pharmaceuticals Incorporated at 1-877-634-8789 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice. The overall safety profile of SYMDEKO is based on data from 1001 patients in three double-blind, placebo-controlled, clinical trials: two parallel-group trials of 12 and 24-week duration and one cross-over design trial of 8 weeks duration. …
Source: FDA drug label, Vertex Pharmaceuticals Incorporated, effective August 21, 2026 (SPL set 302ae804-37db-44fd-ac2f-3dbdeda9aa4b), via openFDA; the full label on DailyMed
What do FAERS reports show?
5,286 reports list ivacaftor and tezacaftor among the medicines taken, each a report of something that happened, not proof the medicine caused it; 74 are coded as a death and 2,899 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Reports rose sharply in 2019 (3,045, against a median of 39 a year): FAERS counts follow reporting, which news, litigation and label changes can drive, not how often a reaction happens. Of the 21 reactions below, 3 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Ivacaftor and tezacaftor: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions