| Adverse events | Pirfenidone 2403 mg·day−1¶ | Placebo+ |
| Nausea | 125 (36) | 60 (17) |
| Rash | 111 (32) | 40 (12) |
| Dyspepsia | 66 (19) | 26 (7) |
| Dizziness | 63 (18) | 35 (10) |
| Vomiting | 47 (14) | 15 (4) |
| Photosensitivity reaction | 42 (12) | 6 (2) |
| Anorexia | 37 (11) | 13 (4) |
| Arthralgia | 36 (10) | 24 (7) |
| Insomnia | 34 (10) | 23 (7) |
| Abdominal distension | 33 (10) | 20 (6) |
| Decreased appetite | 30 (9) | 10 (3) |
| Stomach discomfort | 29 (8) | 6 (2) |
| Weight reduction | 28 (8) | 12 (3) |
| Abdominal pain | 26 (8) | 12 (3) |
| Asthenia | 24 (7) | 13 (4) |
| Pharyngolaryngeal pain | 24 (7) | 16 (5) |
| Pruritus | 22 (6) | 14 (4) |
| Hot flush | 18 (5) | 4 (1) |
Data are presented as n (%). #: occurring in ≥5% of patients given pirfenidone 2,403 mg·day−1 in study 004 or study 006, and with an incidence 1.5 times higher than that in patients given placebo; ¶: n=345; +: n=347. Reproduced from [38] with permission from the publisher.