Pirfenidone side effects: what 40,476 FDA adverse event reports show
Drug class
Pyridone
Who reports
40,476 reports · 55% serious · 9,421 with death outcome · 37% female
Used for
Pirfenidone capsules are indicated for the treatment of idiopathic pulmonary fibrosis (IPF). Pirfenidone is a pyridone indicated for the treatment of idiopathic pulmonary fibrosis (IPF). (1)
What it is
Pirfenidone, USP belongs to the chemical class of pyridone. Pirfenidone capsules, USP are available as a opaque white to off-white hard gelatin capsule containing 267 mg of pirfenidone, USP for oral administration. Pirfenidone, USP has a molecular formula of
Boxed warning
None in the current label
Causality screen of the 40 strongest signals
What the badges mean
- Labeled adverse reaction The exact term appears in the label's warnings or adverse-reactions sections: a known, expected effect. The FAERS signal confirms the label rather than discovering anything.
- Labeled (related wording) The label describes this effect under different wording (e.g. 'neutropenia' for 'neutrophil count decreased'). Treated as known.
- Likely indication confounding The term appears in the label's indications: reports probably describe the disease being treated (or its progression), not a drug effect. Classic confounding by indication.
- Reporting / coding artifact An administrative, monitoring or exposure term (product issue, off-label use, 'test normal', overdose...). Not a biological reaction; a high PRR here reflects how reports are coded.
- Lab value / disease marker A laboratory result, investigation or disease-activity marker (antibody positive, CRP abnormal, swollen joint count) not described in the label. These usually mirror the monitored disease or testing protocol rather than a drug effect; not screened further.
- Not in label — unassessed Not found in the label text, not an artifact pattern. This is a genuine candidate for a formal causality assessment (Bradford Hill / WHO-UMC); it has NOT had one here.
Strongest disproportionality signals
Flagged terms (PRR ≥ 2, χ² ≥ 4, n ≥ 10), ranked by PRR; infinite PRRs (no comparator reports) excluded. The EBGM column is a second, shrinkage-based estimate (MGPS) with its 5th percentile EB05 and the BCPNN IC025; a pair flagged by PRR alone is marked PRR-only and should be read as fragile. The strata column recomputes the PRR on serious reports only (and, for the 300 most-reported drugs, adjusted for age band), and flags pairs whose reports are unusually skewed by sex or come mostly from consumers. Each row also shows the PRR against the other drugs of the same FDA class, which removes most confounding by the condition being treated, and a calibrated p-value: on validation, known non-causes average an ROR of about 2, so significance is judged against that empirical null (✓ = p < 0.05 after calibration). 995 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Forced vital capacity abnormal | 15 | 283.4 150.8–532.7ROR 283.5 · calibrated p 7e-10 ✓ | 148.5 EB05 95.5 · IC025 +3.9 3/3 methods agree | Not in label — unassessed | serious n=15 | not reported in cached trials |
| Forced vital capacity decreased | 128 | 127.5 105.1–154.8ROR 127.9 · calibrated p 2e-8 ✓ | 100.7 EB05 86.9 · IC025 +5.9 3/3 methods agree | Not in label — unassessed | serious n=126 | not reported in cached trials |
| Carbon monoxide diffusing capacity decreased | 31 | 113.8 77.1–167.9ROR 113.9 · calibrated p 1e-7 ✓ | 88.3 EB05 65.2 · IC025 +4.6 3/3 methods agree | Not in label — unassessed | serious n=31 | not reported in cached trials |
| Lung diffusion test decreased | 57 | 87.1 65.8–115.3ROR 87.2 · calibrated p 5e-7 ✓ | 72.8 EB05 58.3 · IC025 +5.1 3/3 methods agree | Not in label — unassessed | serious n=56 · 91% clinician | not reported in cached trials |
| Idiopathic pulmonary fibrosis | 543 | 84.2 77.0–92.2ROR 85.4 · calibrated p 4e-7 ✓ | 72.3 EB05 67.3 · IC025 +5.9 3/3 methods agree | Likely indication confounding term in indications | serious n=529 | NCT00662038: 230/1,058 (21.7%) on Pirfenidone (serious AE) |
| Lung diffusion test abnormal | 10 | 60.7 31.5–117.0ROR 60.7 · calibrated p 3e-5 ✓ | 49.6 EB05 28.8 · IC025 +2.9 3/3 methods agree | Reporting / coding artifact | serious n=10 | not reported in cached trials |
| Pulmonary function test abnormal | 156 | 57.4 48.7–67.7ROR 57.6 · calibrated p 6e-6 ✓ | 51.4 EB05 45.0 · IC025 +5.2 3/3 methods agree | Reporting / coding artifact | serious n=148 | not reported in cached trials |
| Solar dermatitis | 27 | 57.2 38.4–85.1ROR 57.2 · calibrated p 1e-5 ✓ | 49.8 EB05 35.9 · IC025 +4.1 3/3 methods agree | Not in label — unassessed | serious n=13 | not reported in cached trials |
| Fev1/fvc ratio decreased | 10 | 46.8 24.5–89.4ROR 46.8 · calibrated p 1e-4 ✓ | 39.9 EB05 23.2 · IC025 +2.8 3/3 methods agree | Lab value / disease marker | serious n=10 | not reported in cached trials |
| Lung diffusion disorder | 10 | 34.9 18.4–66.3ROR 35.0 · calibrated p 4e-4 ✓ | 31.0 EB05 17.9 · IC025 +2.6 3/3 methods agree | Not in label — unassessed | serious n=10 | not reported in cached trials |
| Pulmonary function test decreased | 231 | 28.7 25.1–32.7ROR 28.8 · calibrated p 3e-4 ✓ | 27.1 EB05 24.3 · IC025 +4.5 3/3 methods agree | Not in label — unassessed | serious n=201 | not reported in cached trials |
| Sunburn | 355 | 25.9 23.3–28.8ROR 26.1 · calibrated p 6e-4 ✓ | 24.6 EB05 22.6 · IC025 +4.4 3/3 methods agree | Not in label — unassessed | serious n=119 | not reported in cached trials |
| Pulmonary artery dilatation | 16 | 25.0 15.2–41.4ROR 25.0 · calibrated p 0.001 ✓ | 23.3 EB05 15.1 · IC025 +3.0 3/3 methods agree | Not in label — unassessed | serious n=16 | not reported in cached trials |
| Photosensitivity reaction (sun sensitivity) | 725 | 23.8 22.1–25.7ROR 24.3 · calibrated p 8e-4 ✓ | 22.8 EB05 21.4 · IC025 +4.4 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 15.0 | NCT00662038: 1/1,058 (0.1%) on Pirfenidone (serious AE) |
| Dependence on oxygen therapy | 21 | 23.6 15.3–36.6ROR 23.7 · calibrated p 0.001 ✓ | 22.2 EB05 15.3 · IC025 +3.2 3/3 methods agree | Reporting / coding artifact | serious n=21 · 86% consumer | not reported in cached trials |
| Clubbing | 17 | 22.4 13.8–36.3ROR 22.4 · calibrated p 0.002 ✓ | 20.9 EB05 13.7 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious n=16 | not reported in cached trials |
| Total lung capacity decreased | 60 | 20.1 15.6–26.0ROR 20.2 · calibrated p 0.002 ✓ | 19.3 EB05 15.5 · IC025 +3.6 3/3 methods agree | Not in label — unassessed | serious n=49 | not reported in cached trials |
| Oxygen consumption increased | 71 | 16.0 12.7–20.3ROR 16.1 · calibrated p 0.006 ✓ | 15.5 EB05 12.7 · IC025 +3.4 3/3 methods agree | Lab value / disease marker | serious n=46 | not reported in cached trials |
| Lung transplant | 102 | 15.2 12.5–18.5ROR 15.3 · calibrated p 0.007 ✓ | 14.7 EB05 12.5 · IC025 +3.5 3/3 methods agree | Not in label — unassessed | serious n=91 | not reported in cached trials |
| Walking distance test abnormal | 11 | 15.2 8.3–27.6ROR 15.2 · calibrated p 0.012 ✓ | 13.3 EB05 6.9 · IC025 +2.2 3/3 methods agree | Reporting / coding artifact | serious n=10 | not reported in cached trials |
| Respiratory gas exchange disorder | 10 | 14.3 7.6–26.9ROR 14.3 · calibrated p 0.016 ✓ | 12.1 EB05 6.0 · IC025 +2.0 3/3 methods agree | Not in label — unassessed | serious n=10 | not reported in cached trials |
| Restrictive pulmonary disease | 31 | 14.1 9.9–20.1ROR 14.1 · calibrated p 0.011 ✓ | 13.4 EB05 9.6 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious n=31 · 100% clinician | not reported in cached trials |
| Chronic respiratory failure | 30 | 13.4 9.3–19.2ROR 13.4 · calibrated p 0.014 ✓ | 12.6 EB05 9.0 · IC025 +2.8 3/3 methods agree | Not in label — unassessed | serious n=30 | NCT00662038: 30/1,058 (2.8%) on Pirfenidone (serious AE) |
| Pharyngeal mass | 12 | 12.0 6.7–21.2ROR 12.0 · calibrated p 0.027 ✓ | 10.0 EB05 5.5 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious n=10 | not reported in cached trials |
| Amblyopia | 13 | 11.6 6.7–20.2ROR 11.6 · calibrated p 0.028 ✓ | 9.8 EB05 5.6 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious n=13 | not reported in cached trials |
| Sputum increased | 42 | 10.5 7.7–14.2ROR 10.5 · calibrated p 0.031 ✓ | 9.8 EB05 7.4 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious n=22 · 86% consumer | not reported in cached trials |
| Food aversion | 32 | 10.1 7.1–14.3ROR 10.1 · calibrated p 0.036 ✓ | 9.3 EB05 6.7 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious n=24 · ♀ 17% (drug 37%) | not reported in cached trials |
| Lower respiratory tract congestion | 32 | 9.9 7.0–14.0ROR 9.9 · calibrated p 0.039 ✓ | 9.1 EB05 6.6 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious n=18 · 75% consumer | not reported in cached trials |
| Pulmonary fibrosis | 353 | 9.7 8.8–10.8ROR 9.8 · calibrated p 0.035 ✓ | 9.5 EB05 8.7 · IC025 +3.1 3/3 methods agree | Likely indication confounding term in indications | serious PRR 9.9 | NCT00662038: 230/1,058 (21.7%) on Pirfenidone (serious AE) |
| Irregular breathing | 10 | 9.0 4.8–16.8ROR 9.0 · calibrated p 0.067 | 6.9 EB05 3.8 · IC025 +1.6 3/3 methods agree | Not in label — unassessed | serious n=10 | not reported in cached trials |
| Fibrosis | 52 | 8.9 6.8–11.7ROR 8.9 · calibrated p 0.052 | 8.4 EB05 6.5 · IC025 +2.6 3/3 methods agree | Likely indication confounding term in indications | serious n=47 · 74% consumer | NCT00662038: 230/1,058 (21.7%) on Pirfenidone (serious AE) |
| Gastric disorder | 573 | 8.7 8.0–9.4ROR 8.8 · calibrated p 0.050 | 8.5 EB05 7.9 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious PRR 7.7 · 76% consumer | NCT00662038: 1/1,058 (0.1%) on Pirfenidone (serious AE) |
| Pulmonary pain | 47 | 8.6 6.4–11.5ROR 8.6 · calibrated p 0.058 | 8.0 EB05 6.2 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious n=30 | not reported in cached trials |
| Small cell lung cancer | 22 | 7.9 5.2–12.0ROR 7.9 · calibrated p 0.081 | 6.9 EB05 4.7 · IC025 +2.0 3/3 methods agree | Not in label — unassessed | serious n=22 | NCT00662038: 5/1,058 (0.5%) on Pirfenidone (serious AE) |
| Aortic dilatation | 16 | 7.7 4.7–12.6ROR 7.7 · calibrated p 0.092 | 6.5 EB05 4.1 · IC025 +1.8 3/3 methods agree | Not in label — unassessed | serious n=16 | not reported in cached trials |
| Oxygen saturation decreased | 795 | 7.5 7.0–8.0ROR 7.6 · calibrated p 0.078 | 7.4 EB05 6.9 · IC025 +2.8 3/3 methods agree | Lab value / disease marker | serious PRR 7.4 | not reported in cached trials |
| Haemochromatosis | 13 | 7.4 4.3–12.9ROR 7.4 · calibrated p 0.105 | 6.1 EB05 3.7 · IC025 +1.6 3/3 methods agree | Not in label — unassessed | serious n=13 | not reported in cached trials |
| International normalised ratio decreased | 58 | 7.4 5.7–9.6ROR 7.5 · calibrated p 0.087 | 7.0 EB05 5.6 · IC025 +2.4 3/3 methods agree | Lab value / disease marker | serious n=43 · ♀ 13% (drug 37%) | not reported in cached trials |
| Decreased appetite (loss of appetite) | 3,272 | 7.4 7.2–7.7ROR 8.0 · calibrated p 0.067 | 7.3 EB05 7.1 · IC025 +2.8 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 5.2 | NCT00662038: 95/1,058 (9.0%) on Pirfenidone |
| Chest injury | 28 | 7.2 4.9–10.4ROR 7.2 · calibrated p 0.103 | 6.4 EB05 4.6 · IC025 +2.0 3/3 methods agree | Labeled (related wording) related wording | serious n=28 · ♀ 7% (drug 37%) | not reported in cached trials |
Trial evidence (ClinicalTrials.gov)
✓ Trial adverse-event data found on ClinicalTrials.gov
Largest completed trials with posted results that list Pirfenidone as a study intervention. The right-hand column of the signal table shows whether each FAERS term was also recorded in these trials, with a real denominator (8 of 40 signal terms matched).
- NCT00662038 — Open-Label Study of the Long Term Safety of Pirfenidone in Patients With Idiopathic Pulmonary Fibrosis (IPF) (N=1058, PHASE3; 420 AE terms posted; arms: Pirfenidone)
Caveats: trial populations, doses and follow-up differ from the reporting population; AE terms are sponsor-coded and matched here by wording; absence from a trial list means the term was not reported above the sponsor's frequency threshold, not that it cannot occur.
Most frequently reported reactions
By raw co-report count, regardless of disproportionality. Common terms here are often the illness itself or generic outcomes.
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Death | 7,511 | 4.5 4.5–4.6ROR 5.4 · calibrated p 0.199 | 4.5 EB05 4.4 · IC025 +2.1 3/3 methods agree | Outcome field, not a reaction | serious PRR 4.7 | NCT00662038: 2/1,058 (0.2%) on Pirfenidone (serious AE) |
| Nausea | 5,174 | 3.4 3.3–3.5ROR 3.8 · calibrated p 0.424 | 3.4 EB05 3.3 · IC025 +1.7 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.4 · 73% consumer | NCT00662038: 2/1,058 (0.2%) on Pirfenidone (serious AE) |
| Fatigue (tiredness) | 3,806 | 2.5 2.5–2.6ROR 2.7 · calibrated p 0.730 | 2.5 EB05 2.5 · IC025 +1.3 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.0 · 71% consumer | NCT00662038: 210/1,058 (19.8%) on Pirfenidone |
| Diarrhoea (diarrhea) | 3,279 | 2.6 2.6–2.7ROR 2.8 · calibrated p 0.697 | 2.6 EB05 2.6 · IC025 +1.3 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 1.7 · 74% consumer | NCT00662038: 242/1,058 (22.9%) on Pirfenidone |
| Decreased appetite (loss of appetite) | 3,272 | 7.4 7.2–7.7ROR 8.0 · calibrated p 0.067 | 7.3 EB05 7.1 · IC025 +2.8 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 5.2 | NCT00662038: 95/1,058 (9.0%) on Pirfenidone |
| Dyspnoea (shortness of breath) | 2,963 | 2.7 2.6–2.8ROR 2.9 · calibrated p 0.674 | 2.7 EB05 2.6 · IC025 +1.4 3/3 methods agree | Not in label — unassessed | serious PRR 2.8 | NCT00662038: 8/1,058 (0.8%) on Pirfenidone (serious AE) |
| Weight decreased (weight loss) | 2,231 | 4.2 4.0–4.3ROR 4.4 · calibrated p 0.318 | 4.1 EB05 4.0 · IC025 +2.0 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 3.3 | NCT00662038: 153/1,058 (14.5%) on Pirfenidone |
| Dizziness | 2,188 | 2.3 2.2–2.4ROR 2.4 · calibrated p 0.877 | 2.3 EB05 2.2 · IC025 +1.1 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 1.8 · 71% consumer | NCT00662038: 1/1,058 (0.1%) on Pirfenidone (serious AE) |
| Cough | 2,064 | 3.8 3.7–4.0ROR 4.0 · calibrated p 0.379 | 3.8 EB05 3.7 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 3.9 | NCT00662038: 1/1,058 (0.1%) on Pirfenidone (serious AE) |
| Rash | 2,039 | 2.4 2.3–2.5ROR 2.5 · calibrated p 0.805 | 2.4 EB05 2.3 · IC025 +1.2 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 1.8 | NCT00662038: 156/1,058 (14.7%) on Pirfenidone |
| Vomiting | 1,809 | 2.0 1.9–2.1ROR 2.0 · calibrated p 0.971 | 2.0 EB05 1.9 · IC025 +0.9 | Labeled adverse reaction exact term | serious PRR 1.2 · 71% consumer | NCT00662038: 2/1,058 (0.2%) on Pirfenidone (serious AE) |
| Pneumonia (lung infection) | 1,784 | 2.9 2.7–3.0ROR 3.0 · calibrated p 0.641 | 2.9 EB05 2.7 · IC025 +1.4 3/3 methods agree | Labeled (related wording) related wording | serious PRR 3.0 | NCT00662038: 1/1,058 (0.1%) on Pirfenidone (serious AE) |
| Abdominal discomfort | 1,686 | 5.3 5.0–5.5ROR 5.5 · calibrated p 0.191 | 5.2 EB05 5.0 · IC025 +2.3 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 4.3 · 74% consumer | not reported in cached trials |
| Headache | 1,517 | 1.3 1.2–1.3ROR 1.3 · calibrated p 0.485 | 1.3 EB05 1.2 · IC025 +0.2 | Labeled adverse reaction exact term | serious PRR 1.0 · 73% consumer | NCT00662038: 1/1,058 (0.1%) on Pirfenidone (serious AE) |
| Abdominal pain upper | 1,510 | 3.8 3.6–4.0ROR 3.9 · calibrated p 0.389 | 3.8 EB05 3.6 · IC025 +1.8 3/3 methods agree | Labeled (related wording) related wording | serious PRR 2.3 · 80% consumer | NCT00662038: 60/1,058 (5.7%) on Pirfenidone |
Unlabeled candidate signals
These flagged terms were not found in the FDA label text and do not match an artifact pattern. They are the pairs that would merit a structured assessment (temporality, dose-response, biological plausibility, consistency across databases, trial or cohort evidence). The screen has not done that; string-matching misses label wording, and a strong PRR can still be stimulated reporting, co-medication, or the disease itself.
- Forced vital capacity decreased — n=128, PRR 127.5
- Carbon monoxide diffusing capacity decreased — n=31, PRR 113.8
- Lung diffusion test decreased — n=57, PRR 87.1
- Solar dermatitis — n=27, PRR 57.2
- Pulmonary function test decreased — n=231, PRR 28.7
- Sunburn — n=355, PRR 25.9
- Total lung capacity decreased — n=60, PRR 20.1
- Lung transplant — n=102, PRR 15.2
- Restrictive pulmonary disease — n=31, PRR 14.1
- Chronic respiratory failure — n=30, PRR 13.4 (also seen in trial arm)
Want to assess one of these properly? The runbook describes the Bradford Hill / trial-evidence workflow used on the assessment page, and handoff_top1000_signals.csv lists the strongest unassessed pairs across all drugs.
Common questions
What are the most reported side effects of Pirfenidone?
In FDA FAERS, the most frequently co-reported reaction terms for Pirfenidone are nausea, fatigue, diarrhoea, decreased appetite, dyspnoea, weight decreased. These are report counts, not rates: FAERS has no denominator, reporting is voluntary and uneven, and a term can be reported because of the illness being treated rather than the drug.
Does Pirfenidone have an FDA boxed warning?
No. The FDA label retrieved for Pirfenidone has no boxed warning; see the label's Warnings and Precautions for the recognised risks.
Do FAERS signals prove that Pirfenidone causes these side effects?
No. A disproportionality signal (PRR, ROR) means a reaction is reported more often with this drug than with others in the database. That can reflect a real effect, but also the disease being treated, stimulated reporting after news or litigation, co-medications, or how reports are coded. Causality needs temporality, dose-response, biological plausibility, consistency across data sources and, ideally, trial or cohort evidence. This page screens each term against the FDA label and ClinicalTrials.gov results; it does not establish causation.
Sources & methods
- FDA label via openFDA (set ID 07ff87b3-0a88-15b4-e063-6294a90a72ab, effective 20260114; matched on
openfda.generic_name.exact:"PIRFENIDONE") - Bayesian shrinkage measures computed offline over all 1,317,300 cached pairs: BCPNN information component (IC, with Norén closed-form IC025) and MGPS empirical-Bayes geometric mean (EBGM, EB05) with a two-component gamma prior fitted by maximum marginal likelihood (α₁=0.57, β₁=0.02, α₂=1.42, β₂=0.70, w=0.17); unstratified
- FAERS pair statistics from the OpenPV build of 2026-09-14 (openFDA
count=aggregation, fieldpatient.drug.openfda.generic_name.exact, 1,035 reaction terms, min 3 co-reports); PRR/ROR with 95% CI, chi-square with Yates correction - Serious-only and stratified counts (serious:1, patient.patientsex, primarysource.qualification) from openFDA count queries; serious-only PRR uses the drug serious report total and the term global serious total (N_serious=11,882,979); strata shown only when n ≥ 20
- Seriousness and sex counts from openFDA
count=serious,patient.patientsex,seriousnessdeath - ClinicalTrials.gov API v2 (query
PIRFENIDONE, results-bearing studies sorted by enrollment)
Page generated 2026-10-14. Label and PubChem text are retrieved automatically and may lag the current label; always check the current prescribing information. OpenPV is a beta research tool of the Open Source Medicine Foundation.