Participants will receive one 267 milligrams (mg) oral pirfenidone capsule three times daily (TID) (801 mg per day [mg/day]) for 2 weeks followed by two 267 mg oral pirfenidone capsules TID (1602 mg/day) for 2 weeks (titration period) and then three 267 mg oral pirfenidone capsules TID (2403 mg/day) for 12 weeks maintenance period).

Participants will receive one 267 mg oral pirfenidone capsule TID (801 mg/day) for 1 week followed by two 267 mg oral pirfenidone capsules TID (1602 mg/day) for 1 week (titration period) and then three 267 mg oral pirfenidone capsules TID (2403 mg/day) for 14 weeks (maintenance period).

Pirfenidone will be administered orally at a dose of 267 mg one oral capsule TID (801 mg/day) for 1 or 2 weeks followed by two 267 mg oral capsules TID (1602 mg/day) for 1 or 2 weeks (titration period) and then three 267 mg oral capsules TID (2403 mg/day) for 12 weeks (maintenance period).

Percentage of participants who had treatment-emergent AEs, defined as newly occurring or worsening after first dose. Relatedness to (study drug) was assessed by the investigator (Yes/No). Participants with multiple occurrences of an AE within a category were counted once within the category.

An SAE was an AE resulting in any of the following outcomes or deemed significant for any other reason: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly. Treatment-emergent are events between first dose of study drug and up to 28 days after last dose that were absent before treatment or that worsened relative to pretreatment state.

UCLA SCTC GIT Scale 2.0 is a 34-item self-administered questionnaire to obtain participant's assessment of the frequency of GI symptoms in preceding 7 days and how symptoms affected his/her life. All but 2 items were scored on a 0 to 3 scale (0=better health, 3=worse health); remaining 2 items were scored as 0 (better health) and 1 (worse health). The 34 items are divided into seven scales (reflux, distention/bloating, fecal soilage, diarrhea, social functioning, emotional well-being, and constipation). Individual scale score was calculated as the average of the items in the scale. Individual scale score ranged from 0 to 3 for reflux, distention/bloating, fecal soilage, social functioning, and emotional well-being; 0 to 2 for diarrhea; and 0 to 2.5 for constipation. A total score was also calculated as the average of 6 of the 7 scales (omitting constipation) and ranged from 0 to 2.83. For individual and total scores 0 indicated better health and higher score indicates worse health.