Drug · FAERS side-effect profile with label screen
Istradefylline side effects: what 5,920 FDA adverse event reports show
Drug class
Adenosine receptor antagonist
FDA label, Indications wording
Brand names
Nourianz
openFDA label
Who reports
5,920 reports · 44% serious · 928 with death outcome · 40% female
openFDA FAERS counts, all years, deduplication not applied
Used for
NOURIANZ is indicated as adjunctive treatment to levodopa/carbidopa in adult patients with Parkinson's disease (PD) experiencing "off" episodes. NOURIANZ is an adenosine receptor antagonist indicated as adjunctive treatment to levodopa/carbidopa in adult patients with Parkinson's disease (PD) experiencing "off" episodes ( 1 ).
FDA label, Indications and Usage
What it is
NOURIANZ contains istradefylline, an adenosine receptor antagonist, which has a xanthine derivative structure.
FDA label, Description section
Boxed warning
None in the current label
How to read this page. FAERS is a spontaneous-reporting system: counts are not incidence rates and a signal is not proof of causation.
Each reaction below is run through an automated screen — is the term in the FDA label (known), in the indications (the disease being treated), an administrative/coding term, or none of these (unlabeled)?
That screen is mechanical text matching, not a causality assessment. The 30 hand-written Bradford Hill assessments are on the causality assessment page. Not medical advice.
Causality screen of the 40 strongest signals
Labeled adverse reaction 5Labeled (related wording) 3Reporting / coding artifact 12Not in label — unassessed 20
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.
- 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.
- 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 flags pairs whose reports are unusually skewed by sex or come mostly from consumers rather than clinicians. 87 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.
Show:
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Dyskinesia (involuntary movements) | 482 | 42.6 39.1–46.4ROR 46.3 · χ² 19,337 / p <1e-300 | 42.0 EB05 39.0 · IC025 +5.2 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 21.5 | no trial data cached |
| Hallucination (hallucinations) | 608 | 29.0 26.8–31.2ROR 32.2 · χ² 16,308 / p <1e-300 | 28.7 EB05 26.8 · IC025 +4.7 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 42.8 | no trial data cached |
| Therapy non-responder | 252 | 20.1 17.8–22.7ROR 21.0 · χ² 4,547 / p <1e-300 | 20.0 EB05 18.0 · IC025 +4.1 3/3 methods agree | Reporting / coding artifact | serious PRR 8.3 · 93% clinician | no trial data cached |
| Hallucination, visual | 75 | 12.7 10.1–15.9ROR 12.9 · χ² 795 / p 4e-175 | 12.5 EB05 10.2 · IC025 +3.2 3/3 methods agree | Labeled (related wording) related wording | serious PRR 17.2 | no trial data cached |
| Product dispensing error | 73 | 11.9 9.5–15.0ROR 12.1 · χ² 718 / p 2e-158 | 11.7 EB05 9.5 · IC025 +3.1 3/3 methods agree | Reporting / coding artifact | serious n=17 | no trial data cached |
| Hospice care | 32 | 11.5 8.2–16.3ROR 11.6 · χ² 297 / p 8e-67 | 11.0 EB05 7.9 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious PRR 19.1 · 90% clinician | no trial data cached |
| Delusion | 49 | 11.2 8.5–14.9ROR 11.3 · χ² 446 / p 3e-99 | 10.9 EB05 8.4 · IC025 +2.9 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 14.5 | no trial data cached |
| Therapy partial responder | 28 | 6.6 4.6–9.5ROR 6.6 · χ² 127 / p 8e-30 | 6.0 EB05 4.3 · IC025 +2.0 3/3 methods agree | Reporting / coding artifact | serious PRR 3.4 | no trial data cached |
| Device occlusion | 25 | 6.4 4.3–9.4ROR 6.4 · χ² 108 / p 1e-25 | 5.8 EB05 4.1 · IC025 +1.9 3/3 methods agree | Reporting / coding artifact | serious n=16 · ♀ 64% (drug 40%) · 76% consumer | no trial data cached |
| Constipation | 353 | 5.8 5.2–6.4ROR 6.1 · χ² 1,405 / p <1e-300 | 5.7 EB05 5.3 · IC025 +2.3 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 3.9 | no trial data cached |
| Tremor (shaking) | 268 | 5.7 5.1–6.4ROR 5.9 · χ² 1,045 / p 1e-229 | 5.7 EB05 5.1 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious PRR 2.9 | no trial data cached |
| Muscle rigidity | 19 | 5.6 3.6–8.8ROR 5.7 · χ² 68 / p 9e-17 | 5.0 EB05 3.4 · IC025 +1.6 3/3 methods agree | Not in label — unassessed | serious PRR 5.2 | no trial data cached |
| Sleep disorder | 111 | 5.6 4.7–6.8ROR 5.7 · χ² 418 / p 3e-93 | 5.5 EB05 4.7 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious PRR 4.7 | no trial data cached |
| Adverse drug reaction | 138 | 5.5 4.6–6.5ROR 5.6 · χ² 501 / p 3e-111 | 5.4 EB05 4.7 · IC025 +2.1 3/3 methods agree | Reporting / coding artifact | serious PRR 4.8 | no trial data cached |
| Condition aggravated | 451 | 5.3 4.8–5.8ROR 5.7 · χ² 1,588 / p <1e-300 | 5.3 EB05 4.9 · IC025 +2.2 3/3 methods agree | Reporting / coding artifact | serious PRR 3.7 | no trial data cached |
| Balance disorder | 121 | 5.0 4.2–5.9ROR 5.0 · χ² 379 / p 1e-84 | 4.9 EB05 4.2 · IC025 +2.0 3/3 methods agree | Not in label — unassessed | serious PRR 2.8 | no trial data cached |
| Movement disorder | 45 | 4.9 3.7–6.6ROR 5.0 · χ² 138 / p 4e-32 | 4.7 EB05 3.7 · IC025 +1.7 3/3 methods agree | Not in label — unassessed | serious PRR 2.9 | no trial data cached |
| Hallucination, auditory | 22 | 4.9 3.2–7.4ROR 4.9 · χ² 64 / p 5e-16 | 4.5 EB05 3.1 · IC025 +1.5 3/3 methods agree | Labeled (related wording) related wording | serious PRR 7.1 | no trial data cached |
| Adverse reaction | 18 | 4.8 3.0–7.6ROR 4.8 · χ² 51 / p 6e-13 | 4.3 EB05 2.9 · IC025 +1.3 3/3 methods agree | Reporting / coding artifact | serious n=1 | no trial data cached |
| Nightmare | 45 | 4.6 3.4–6.1ROR 4.6 · χ² 123 / p 8e-29 | 4.4 EB05 3.4 · IC025 +1.6 3/3 methods agree | Not in label — unassessed | serious PRR 4.5 | no trial data cached |
| Paranoia | 22 | 4.5 3.0–6.8ROR 4.5 · χ² 56 / p 3e-14 | 4.1 EB05 2.9 · IC025 +1.3 3/3 methods agree | Not in label — unassessed | serious PRR 6.1 | no trial data cached |
| Product dose omission issue | 361 | 4.5 4.1–5.0ROR 4.7 · χ² 990 / p 1e-217 | 4.5 EB05 4.1 · IC025 +2.0 3/3 methods agree | Reporting / coding artifact | serious PRR 7.6 | no trial data cached |
| Incontinence | 13 | 4.4 2.5–7.5ROR 4.4 · χ² 30 / p 2e-8 | 3.8 EB05 2.4 · IC025 +1.0 3/3 methods agree | Not in label — unassessed | serious PRR 2.4 | no trial data cached |
| Drug effect less than expected | 17 | 4.3 2.7–6.9ROR 4.3 · χ² 39 / p 2e-10 | 3.9 EB05 2.6 · IC025 +1.1 3/3 methods agree | Reporting / coding artifact | serious n=3 | no trial data cached |
| Abnormal dreams | 33 | 4.2 3.0–5.9ROR 4.2 · χ² 78 / p 6e-19 | 4.0 EB05 3.0 · IC025 +1.4 3/3 methods agree | Not in label — unassessed | serious PRR 3.6 | no trial data cached |
| Device use issue | 20 | 4.1 2.6–6.3ROR 4.1 · χ² 44 / p 2e-11 | 3.8 EB05 2.6 · IC025 +1.2 3/3 methods agree | Reporting / coding artifact | serious n=5 · ♀ 70% (drug 40%) · 90% consumer | no trial data cached |
| Dizziness postural | 11 | 4.1 2.2–7.3ROR 4.1 · χ² 22 / p 1e-6 | 3.5 EB05 2.1 · IC025 +0.8 3/3 methods agree | Not in label — unassessed | serious n=5 | no trial data cached |
| Disease progression | 135 | 4.1 3.4–4.8ROR 4.1 · χ² 309 / p 1e-69 | 4.0 EB05 3.5 · IC025 +1.7 3/3 methods agree | Reporting / coding artifact | serious PRR 3.1 | no trial data cached |
| Therapeutic response shortened | 35 | 3.9 2.8–5.4ROR 3.9 · χ² 73 / p 8e-18 | 3.7 EB05 2.8 · IC025 +1.3 3/3 methods agree | Reporting / coding artifact | serious PRR 10.7 | no trial data cached |
| Hip fracture | 35 | 3.9 2.8–5.4ROR 3.9 · χ² 72 / p 1e-17 | 3.7 EB05 2.8 · IC025 +1.3 3/3 methods agree | Not in label — unassessed | serious PRR 5.1 | no trial data cached |
| Dystonia | 21 | 3.8 2.5–5.9ROR 3.8 · χ² 41 / p 8e-11 | 3.6 EB05 2.5 · IC025 +1.1 3/3 methods agree | Not in label — unassessed | serious PRR 5.0 | no trial data cached |
| Dementia | 29 | 3.7 2.6–5.3ROR 3.7 · χ² 54 / p 9e-14 | 3.5 EB05 2.6 · IC025 +1.2 3/3 methods agree | Not in label — unassessed | serious PRR 4.8 | no trial data cached |
| Fall | 344 | 3.7 3.3–4.1ROR 3.8 · χ² 675 / p 4e-149 | 3.6 EB05 3.3 · IC025 +1.7 3/3 methods agree | Not in label — unassessed | serious PRR 4.0 | no trial data cached |
| Orthostatic hypotension (dizziness on standing) | 18 | 3.7 2.3–5.8ROR 3.7 · χ² 32 / p 7e-9 | 3.4 EB05 2.3 · IC025 +1.0 3/3 methods agree | Not in label — unassessed | serious PRR 4.5 | no trial data cached |
| Pneumonia aspiration | 25 | 3.6 2.4–5.3ROR 3.6 · χ² 43 / p 2e-11 | 3.4 EB05 2.4 · IC025 +1.1 3/3 methods agree | Not in label — unassessed | serious PRR 4.7 | no trial data cached |
| Gait inability | 32 | 3.4 2.4–4.8ROR 3.4 · χ² 53 / p 2e-13 | 3.3 EB05 2.4 · IC025 +1.1 3/3 methods agree | Not in label — unassessed | serious PRR 3.3 | no trial data cached |
| Head injury | 30 | 3.4 2.4–4.8ROR 3.4 · χ² 48 / p 3e-12 | 3.2 EB05 2.4 · IC025 +1.1 3/3 methods agree | Not in label — unassessed | serious PRR 4.2 | no trial data cached |
| Delirium | 32 | 3.3 2.3–4.6ROR 3.3 · χ² 48 / p 2e-12 | 3.2 EB05 2.3 · IC025 +1.1 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 4.2 | no trial data cached |
| Gait disturbance | 174 | 3.2 2.8–3.7ROR 3.3 · χ² 265 / p 6e-60 | 3.2 EB05 2.8 · IC025 +1.4 3/3 methods agree | Not in label — unassessed | serious PRR 2.2 | no trial data cached |
| Confusional state (confusion) | 146 | 3.2 2.7–3.8ROR 3.3 · χ² 220 / p 5e-50 | 3.2 EB05 2.8 · IC025 +1.4 3/3 methods agree | Labeled (related wording) related wording | serious PRR 2.5 | no trial data cached |
Trial evidence (ClinicalTrials.gov)
Trial cross-check not yet run for this drug (ClinicalTrials.gov pull covers the 800 most-reported drugs first).
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 | 719 | 3.0 2.8–3.2ROR 3.2 · χ² 969 / p 4e-213 | 3.0 EB05 2.8 · IC025 +1.4 3/3 methods agree | Outcome field, not a reaction | serious PRR 3.9 | no trial data cached |
| Drug ineffective (drug did not work) | 627 | 1.7 1.6–1.8ROR 1.8 · χ² 186 / p 1e-42 | 1.7 EB05 1.6 · IC025 +0.6 | Reporting / coding artifact | serious PRR 1.0 | no trial data cached |
| Hallucination (hallucinations) | 608 | 29.0 26.8–31.2ROR 32.2 · χ² 16,308 / p <1e-300 | 28.7 EB05 26.8 · IC025 +4.7 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 42.8 | no trial data cached |
| Dyskinesia (involuntary movements) | 482 | 42.6 39.1–46.4ROR 46.3 · χ² 19,337 / p <1e-300 | 42.0 EB05 39.0 · IC025 +5.2 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 21.5 | no trial data cached |
| Condition aggravated | 451 | 5.3 4.8–5.8ROR 5.7 · χ² 1,588 / p <1e-300 | 5.3 EB05 4.9 · IC025 +2.2 3/3 methods agree | Reporting / coding artifact | serious PRR 3.7 | no trial data cached |
| Dizziness | 421 | 3.0 2.7–3.3ROR 3.1 · χ² 571 / p 1e-126 | 3.0 EB05 2.8 · IC025 +1.4 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 1.9 | no trial data cached |
| Product dose omission issue | 361 | 4.5 4.1–5.0ROR 4.7 · χ² 990 / p 1e-217 | 4.5 EB05 4.1 · IC025 +2.0 3/3 methods agree | Reporting / coding artifact | serious PRR 7.6 | no trial data cached |
| Constipation | 353 | 5.8 5.2–6.4ROR 6.1 · χ² 1,405 / p <1e-300 | 5.7 EB05 5.3 · IC025 +2.3 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 3.9 | no trial data cached |
| Fall | 344 | 3.7 3.3–4.1ROR 3.8 · χ² 675 / p 4e-149 | 3.6 EB05 3.3 · IC025 +1.7 3/3 methods agree | Not in label — unassessed | serious PRR 4.0 | no trial data cached |
| Tremor (shaking) | 268 | 5.7 5.1–6.4ROR 5.9 · χ² 1,045 / p 1e-229 | 5.7 EB05 5.1 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious PRR 2.9 | no trial data cached |
| Therapy non-responder | 252 | 20.1 17.8–22.7ROR 21.0 · χ² 4,547 / p <1e-300 | 20.0 EB05 18.0 · IC025 +4.1 3/3 methods agree | Reporting / coding artifact | serious PRR 8.3 · 93% clinician | no trial data cached |
| Insomnia (trouble sleeping) | 226 | 3.0 2.6–3.4ROR 3.1 · χ² 303 / p 3e-68 | 3.0 EB05 2.7 · IC025 +1.4 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.6 | no trial data cached |
| Gait disturbance | 174 | 3.2 2.8–3.7ROR 3.3 · χ² 265 / p 6e-60 | 3.2 EB05 2.8 · IC025 +1.4 3/3 methods agree | Not in label — unassessed | serious PRR 2.2 | no trial data cached |
| Confusional state (confusion) | 146 | 3.2 2.7–3.8ROR 3.3 · χ² 220 / p 5e-50 | 3.2 EB05 2.8 · IC025 +1.4 3/3 methods agree | Labeled (related wording) related wording | serious PRR 2.5 | no trial data cached |
| Adverse drug reaction | 138 | 5.5 4.6–6.5ROR 5.6 · χ² 501 / p 3e-111 | 5.4 EB05 4.7 · IC025 +2.1 3/3 methods agree | Reporting / coding artifact | serious PRR 4.8 | no trial data cached |
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.
- Hospice care — n=32, PRR 11.5
- Tremor — n=268, PRR 5.7
- Sleep disorder — n=111, PRR 5.6
- Balance disorder — n=121, PRR 5.0
- Movement disorder — n=45, PRR 4.9
- Nightmare — n=45, PRR 4.6
- Paranoia — n=22, PRR 4.5
- Abnormal dreams — n=33, PRR 4.2
- Hip fracture — n=35, PRR 3.9
- Dystonia — n=21, PRR 3.8
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 Istradefylline?
In FDA FAERS, the most frequently co-reported reaction terms for Istradefylline are hallucination, dyskinesia, dizziness, constipation, fall, tremor. 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 Istradefylline have an FDA boxed warning?
No. The FDA label retrieved for Istradefylline has no boxed warning; see the label's Warnings and Precautions for the recognised risks.
Do FAERS signals prove that Istradefylline 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 a7d008cb-b273-4049-a5d2-9c6902910d58, effective 20250520; matched on
openfda.generic_name.exact:"ISTRADEFYLLINE") - 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, 127 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
Page generated 2026-10-08. 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.