Frequency of occurrence of adverse events occurring in more than one subject in any VX-809 treatment group (listed alphabetically by MedRA term)
| Adverse event, n (%) | Placebo | VX-809 25 mg | VX-809 50 mg | VX-809 100 mg | VX-809 200 mg | Total |
| (n=17) | (n=18) | (n=18) | (n=17) | (n=19) | (n=45) | |
| Cough | 7 (41.2) | 10 (55.6) | 6 (33.3) | 7 (41.2) | 10 (52.6) | 40 (88.9) |
| Headache | 3 (17.6) | 4 (22.2) | 5 (27.8) | 2 (11.8) | 5 (26.3) | 19 (42.2) |
| Rales | 1 (5.9) | 6 (33.3) | 2 (11.1) | 3 (17.6) | 3 (15.8) | 15 (33.3) |
| Productive cough | 3 (17.6) | 2 (11.1) | 0 | 4 (23.5) | 6 (31.6) | 15 (17.8) |
| Dyspnoea | 1 (5.9) | 5 (27.8) | 3 (16.7) | 2 (11.8) | 4 (21.1) | 15 (33.3) |
| Pulmonary exacerbation* | 2 (11.8) | 4 (22.2) | 2 (11.1) | 2 (11.8) | 4 (21.1) | 14 (31.1) |
| Fatigue | 2 (11.8) | 3 (16.7) | 3 (16.7) | 2 (11.8) | 3 (15.8) | 13 (28.9) |
| Fever | 2 (11.8) | 2 (11.1) | 1 (5.6) | 1 (5.9) | 5 (26.3) | 11 (24.4) |
| Nasal congestion | 3 (17.6) | 2 (11.1) | 1 (5.6) | 2 (11.8) | 2 (10.5) | 10 (22.2) |
| Wheezing | 3 (17.6) | 1 (5.6) | 4 (22.2) | 1 (5.9) | 0 | 9 (20) |
| Diarrhoea | 3 (17.6) | 3 (16.7) | 1 (5.6) | 2 (11.8) | 0 | 9 (20) |
| Oropharyngeal pain | 3 (17.6) | 0 | 3 (16.7) | 0 | 2 (10.5) | 8 (17.8) |
| Upper respiratory tract infection | 1 (5.9) | 2 (11.1) | 1 (5.6) | 3 (17.6) | 0 | 7 (15.6) |
| Sinus congestion | 2 (11.8) | 1 (5.6) | 2 (11.1) | 0 | 1 (5.3) | 6 (13.3) |
| Respiration abnormal | 0 | 1 (5.6) | 1 (5.6) | 0 | 4 (21.1) | 6 (13.3) |
| Haemoptysis | 2 (11.8) | 1 (5.6) | 1 (5.6) | 0 | 2 (10.5) | 6 (13.3) |
| Constipation | 0 | 2 (11.1) | 2 (11.1) | 1 (5.9) | 1 (5.3) | 6 (13.3) |
| Abdominal pain | 1 (5.9) | 3 (16.7) | 1 (5.6) | 0 | 1 (5.3) | 6 (13.3) |
| Myalgia | 1 (5.9) | 0 | 3 (16.7) | 0 | 1 (5.3) | 5 (11.1) |
| Post-tussive vomiting | 0 | 0 | 2 (11.1) | 1 (5.9) | 1 (5.3) | 4 (8.9) |
| Nausea | 0 | 3 (16.7) | 0 | 0 | 1 (5.3) | 4 (8.9) |
| Nasopharyngitis | 0 | 1 (5.6) | 0 | 1 (5.9) | 2 (10.5) | 4 (8.9) |
| Dizziness | 0 | 1 (5.6) | 0 | 2 (11.8) | 1 (5.3) | 4 (8.9) |
| Back pain | 0 | 2 (11.1) | 1 (5.6) | 0 | 1 (5.3) | 4 (8.9) |
| Abdominal pain upper | 1 (5.9) | 0 | 0 | 1 (5.9) | 2 (10.5) | 4 (8.9) |
| Sputum abnormal | 0 | 2 (11.1) | 0 | 0 | 1 (5.3) | 3 (6.7) |
| Epistaxis | 1 (5.9) | 0 | 0 | 0 | 2 (10.5) | 3 (6.7) |
| C-reactive protein increased | 0 | 1 (5.6) | 0 | 2 (11.8) | 0 | 3 (6.7) |
| Paranasal sinus hypersecretion | 0 | 2 (11.1) | 0 | 0 | 0 | 2 (4.4) |
| Lung hyperinflation | 0 | 0 | 0 | 2 (11.8) | 0 | 2 (4.4) |
↵* Physician-reported pulmonary exacerbation; coded as cystic fibrosis lung according to MedRA term.