Inclusion Criteria:
1. Patients 18 - 85 years of age
2. Two or more documented attacks of acute pancreatitis, separated by 3 months from one another, defined by at least 2 of the following 3:

1. amylase or lipase values, or both, that are greater than 3 times the upper limit of normal values
2. characteristic cross-sectional imaging
3. typical upper abdominal pain according to the revised Atlanta classification28
3. Drug/placebo treatment to start

1. Mild AP

* Patient is discharged out of the hospital
* 30 days after diagnosis of mild AP
2. Moderate Severe or Severe AP

* Patient is discharged out of hospital
* Intra-abdominal collections are either resolved on imaging, or are improving and asymptomatic and do not warrant any intervention (per treating physician)
4. Ability to understand and the willingness to sign a written informed consent document and medical release
5. Willing and able to comply with trial protocol and follow up
6. 2nd AP episode despite correction of the AP etiology (if identified) after the 1st episode as follows i. Patients with biliary pancreatitis who have undergone cholecystectomy, with or without ERCP (if indicated) ii. Patients with hypertriglyceridemia induced pancreatitis who have serum triglyceride levels below 250 with medication management iii. Patients with medication induced AP developing a 2nd AP episode despite stopping the culprit medication

Exclusion Criteria:
1. Age \< 18 or \> 85 years.
2. Body weight \> 200 kg.
3. Ongoing AP or diagnosis of AP in previous 30 days.
4. Diagnosis of chronic pancreatitis, one of the following

1. Ductal stricture, calcification and/or atrophy, as seen on CT scan/MRI
2. 5 or more of the 9 EUS criteria used to diagnose CP
5. Known hypersensitivity to Pirfenidone.
6. AST/ALT ≥ 2 times the upper normal limit.
7. Alkaline phosphatase ≥ 1.5 times the upper normal limit.
8. Bilirubin higher than upper normal limit.
9. Moderate to severe heart failure and/or coronary heart disease (New York Heart Association (NYHA) Functional Class III/IV).
10. On home oxygen or home mechanical ventilation.
11. Advanced liver disease or cirrhosis.
12. Paralytic ileus or significant nausea and vomiting preventing administration of full liquid diet.
13. Chronic diarrhea.
14. Immunosuppressive disorder or on immunosuppressive medications.
15. Active or advanced malignancy.
16. Known cancer that is end-stage with ongoing palliative care or for which palliative care is appropriate.
17. Known history of infective hepatitis.
18. Ongoing photosensitivity and rash.
19. Known live vaccines or therapeutic infectious agents within one month of admission.
20. Known pregnancy or lactation at the time of admission.
21. Women of childbearing potential who are not on oral or injectable contraceptives or IUDs, and do not consent to practice abstinence/adequate contraception while on, and for 90 days after the administration of the drug/placebo.
22. Known to be currently participating in a trial testing any investigational medicinal product or participation in a clinical study involving a medicinal product in the last three months.
23. Problematic pattern of alcohol use or moderate to severe alcohol use disorder (Appendix 2)
24. Substance use disorder (except recreational or medicinal use of marijuana)
25. Family or personal history of long QT syndrome ( \> 500 msec).
26. Strong CYP1A2 inhibitors (e.g., fluvoxamine, enoxacin) or moderate CYP1A2 Inhibitors (e.g., ciprofloxacin).
27. Medications like sildenafil.
28. Renal disease with GFR \< 30.
29. Any condition other than above that, in the opinion of the investigator, is likely to result in the death of the patient within the next 2 years.
30. Any condition that, in the opinion of the investigator, might be significantly exacerbated by the known side effects associated with the administration of Pirfenidone.

Note: Other protocol defined Inclusion/Exclusion Criteria may apply.

Eligibility last updated 5/13/2024. Questions regarding updates should be directed to the study team contact.