Drug · FAERS side-effect profile with label screen
Benztropine Mesylate side effects: what 2,657 FDA adverse event reports show
Drug class
Not stated in label
Brand names
Benztropine Mesylate
openFDA label
Who reports
2,657 reports · 74% serious · 482 with death outcome · 48% female
openFDA FAERS counts, all years, deduplication not applied
Used for
For use as an adjunct in the therapy of all forms of parkinsonism. Useful also in the control of extrapyramidal disorders (except tardive dyskinesia – see PRECAUTIONS ) due to neuroleptic drugs (e.g., phenothiazines).
FDA label, Indications and Usage
What it is
DESCRIPTION Benztropine mesylate, USP is a synthetic compound containing structural features found in atropine and diphenhydramine. It is a crystalline white powder, very soluble in water, des.
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 (related wording) 2Likely indication confounding 4Reporting / coding artifact 2Lab value / disease marker 1Outcome field, not a reaction 1Not in label — unassessed 30
What the badges mean
- 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.
- Outcome field, not a reaction Death is a report outcome, not a reaction term. It is dominated by the underlying illness; see the seriousness profile and the boxed warning instead.
- 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. 151 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 |
|---|---|---|---|---|---|---|
| Schizophrenia | 44 | 28.7 21.4–38.4ROR 29.1 · χ² 1,143 / p 7e-251 | 28.2 EB05 21.9 · IC025 +3.9 3/3 methods agree | Not in label — unassessed | serious PRR 22.4 | no trial data cached |
| Neuroleptic malignant syndrome | 39 | 26.0 19.0–35.5ROR 26.3 · χ² 909 / p 6e-200 | 25.6 EB05 19.5 · IC025 +3.8 3/3 methods agree | Not in label — unassessed | serious PRR 20.1 · 90% clinician | no trial data cached |
| Hyperlipidaemia | 39 | 25.8 18.9–35.2ROR 26.1 · χ² 901 / p 3e-198 | 25.4 EB05 19.4 · IC025 +3.8 3/3 methods agree | Not in label — unassessed | serious PRR 19.6 | no trial data cached |
| Type 2 diabetes mellitus | 94 | 22.0 18.1–26.9ROR 22.8 · χ² 1,863 / p <1e-300 | 21.9 EB05 18.4 · IC025 +4.0 3/3 methods agree | Not in label — unassessed | serious PRR 15.2 | no trial data cached |
| Dystonia | 50 | 20.3 15.4–26.8ROR 20.7 · χ² 898 / p 1e-197 | 20.1 EB05 15.9 · IC025 +3.6 3/3 methods agree | Not in label — unassessed | serious PRR 16.3 | no trial data cached |
| Sinus tachycardia | 34 | 19.0 13.6–26.5ROR 19.2 · χ² 560 / p 4e-124 | 18.7 EB05 14.0 · IC025 +3.3 3/3 methods agree | Not in label — unassessed | serious PRR 14.1 | no trial data cached |
| Drug withdrawal syndrome neonatal | 34 | 18.0 12.9–25.1ROR 18.2 · χ² 527 / p 5e-117 | 17.7 EB05 13.2 · IC025 +3.3 3/3 methods agree | Not in label — unassessed | serious PRR 13.9 | no trial data cached |
| Parkinsonism | 22 | 17.8 11.8–27.1ROR 18.0 · χ² 332 / p 1e-74 | 17.4 EB05 11.9 · IC025 +3.0 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious PRR 13.0 | no trial data cached |
| Myocarditis | 25 | 17.5 11.8–25.8ROR 17.6 · χ² 371 / p 6e-83 | 17.1 EB05 12.0 · IC025 +3.1 3/3 methods agree | Not in label — unassessed | serious PRR 13.5 | no trial data cached |
| Blood triglycerides increased | 39 | 17.4 12.7–23.8ROR 17.6 · χ² 586 / p 1e-129 | 17.2 EB05 13.1 · IC025 +3.3 3/3 methods agree | Lab value / disease marker | serious PRR 18.4 | no trial data cached |
| Hallucination, auditory | 35 | 17.4 12.5–24.2ROR 17.6 · χ² 524 / p 3e-116 | 17.2 EB05 12.8 · IC025 +3.3 3/3 methods agree | Not in label — unassessed | serious PRR 13.3 | no trial data cached |
| Tardive dyskinesia (persistent involuntary movements) | 62 | 17.2 13.5–22.0ROR 17.6 · χ² 930 / p 2e-204 | 17.1 EB05 13.8 · IC025 +3.5 3/3 methods agree | Likely indication confounding term in indications | serious PRR 14.6 | no trial data cached |
| Muscle rigidity | 24 | 15.9 10.7–23.7ROR 16.0 · χ² 319 / p 1e-71 | 15.5 EB05 10.7 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious PRR 12.0 | no trial data cached |
| Salivary hypersecretion | 20 | 15.8 10.2–24.5ROR 15.9 · χ² 263 / p 2e-59 | 15.3 EB05 10.1 · IC025 +2.8 3/3 methods agree | Not in label — unassessed | serious PRR 15.7 | no trial data cached |
| Psychotic disorder | 57 | 15.3 11.8–19.7ROR 15.6 · χ² 745 / p 3e-164 | 15.1 EB05 12.0 · IC025 +3.3 3/3 methods agree | Labeled (related wording) related wording | serious PRR 12.6 | no trial data cached |
| Bipolar disorder | 21 | 15.2 9.9–23.2ROR 15.3 · χ² 263 / p 2e-59 | 14.6 EB05 9.7 · IC025 +2.8 3/3 methods agree | Not in label — unassessed | serious PRR 13.4 | no trial data cached |
| Obesity | 30 | 14.9 10.4–21.2ROR 15.0 · χ² 374 / p 1e-83 | 14.5 EB05 10.4 · IC025 +3.0 3/3 methods agree | Not in label — unassessed | serious PRR 8.9 | no trial data cached |
| Delusion | 27 | 13.8 9.5–20.1ROR 13.9 · χ² 307 / p 5e-69 | 13.3 EB05 9.3 · IC025 +2.8 3/3 methods agree | Not in label — unassessed | serious PRR 11.9 | no trial data cached |
| Paranoia | 30 | 13.7 9.6–19.5ROR 13.8 · χ² 340 / p 3e-76 | 13.3 EB05 9.5 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious PRR 12.8 · ♀ 86% (drug 48%) | no trial data cached |
| Sedation | 45 | 13.6 10.2–18.2ROR 13.9 · χ² 514 / p 3e-114 | 13.4 EB05 10.3 · IC025 +3.1 3/3 methods agree | Not in label — unassessed | serious PRR 13.9 · ♀ 27% (drug 48%) · 95% clinician | no trial data cached |
| Akathisia (inner restlessness) | 23 | 13.3 8.9–20.0ROR 13.4 · χ² 250 / p 2e-56 | 12.7 EB05 8.5 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious PRR 12.7 | no trial data cached |
| Drug level decreased | 17 | 13.1 8.2–21.1ROR 13.2 · χ² 178 / p 5e-41 | 12.2 EB05 7.5 · IC025 +2.5 3/3 methods agree | Reporting / coding artifact | serious PRR 12.5 | no trial data cached |
| Diabetes mellitus inadequate control | 29 | 12.9 9.0–18.6ROR 13.1 · χ² 307 / p 4e-69 | 12.5 EB05 8.8 · IC025 +2.8 3/3 methods agree | Not in label — unassessed | serious PRR 10.9 | no trial data cached |
| Completed suicide (death by suicide) | 132 | 12.4 10.5–14.6ROR 13.0 · χ² 1,375 / p <1e-300 | 12.3 EB05 10.6 · IC025 +3.3 3/3 methods agree | Outcome field, not a reaction | serious PRR 9.6 · 94% clinician | no trial data cached |
| Diabetes mellitus | 120 | 12.4 10.4–14.8ROR 12.9 · χ² 1,247 / p 2e-273 | 12.3 EB05 10.5 · IC025 +3.3 3/3 methods agree | Not in label — unassessed | serious PRR 9.3 | no trial data cached |
| Extrapyramidal disorder | 39 | 12.3 9.0–16.8ROR 12.5 · χ² 393 / p 9e-88 | 11.9 EB05 8.9 · IC025 +2.9 3/3 methods agree | Likely indication confounding term in indications | serious PRR 8.9 | no trial data cached |
| Diabetic ketoacidosis | 34 | 11.2 8.0–15.7ROR 11.3 · χ² 306 / p 8e-69 | 10.7 EB05 7.8 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious PRR 8.7 | no trial data cached |
| Mitral valve incompetence | 16 | 11.2 6.9–18.2ROR 11.2 · χ² 138 / p 4e-32 | 9.9 EB05 6.0 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious PRR 8.7 | no trial data cached |
| Mydriasis | 18 | 11.1 7.0–17.6ROR 11.2 · χ² 155 / p 6e-36 | 10.0 EB05 6.3 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious PRR 10.5 | no trial data cached |
| Drug toxicity | 19 | 10.9 6.9–17.0ROR 10.9 · χ² 160 / p 5e-37 | 9.8 EB05 6.3 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious PRR 8.7 | no trial data cached |
| Cardiomyopathy | 20 | 10.7 6.9–16.5ROR 10.8 · χ² 166 / p 3e-38 | 9.7 EB05 6.3 · IC025 +2.4 3/3 methods agree | Not in label — unassessed | serious PRR 8.3 | no trial data cached |
| Thinking abnormal | 24 | 10.1 6.8–15.1ROR 10.2 · χ² 188 / p 4e-43 | 9.3 EB05 6.3 · IC025 +2.4 3/3 methods agree | Not in label — unassessed | serious PRR 10.7 · ♀ 22% (drug 48%) | no trial data cached |
| Economic problem | 19 | 9.7 6.2–15.2ROR 9.8 · χ² 140 / p 1e-32 | 8.6 EB05 5.6 · IC025 +2.2 3/3 methods agree | Reporting / coding artifact | serious PRR 8.2 | no trial data cached |
| Leukopenia (low white blood cells) | 60 | 9.5 7.4–12.2ROR 9.7 · χ² 448 / p 8e-100 | 9.2 EB05 7.3 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious PRR 6.3 | no trial data cached |
| Premature baby | 36 | 9.4 6.8–13.0ROR 9.5 · χ² 263 / p 2e-59 | 8.8 EB05 6.5 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious PRR 7.4 | no trial data cached |
| Myoclonus | 14 | 9.3 5.5–15.6ROR 9.3 · χ² 95 / p 9e-23 | 7.8 EB05 4.7 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 6.5 | no trial data cached |
| Mental disorder | 51 | 9.2 7.0–12.1ROR 9.4 · χ² 367 / p 4e-82 | 8.8 EB05 6.9 · IC025 +2.6 3/3 methods agree | Labeled (related wording) related wording | serious PRR 8.3 | no trial data cached |
| Hyperglycaemia (high blood sugar) | 40 | 8.7 6.4–11.8ROR 8.8 · χ² 265 / p 7e-60 | 8.2 EB05 6.2 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious PRR 6.3 | no trial data cached |
| Dyskinesia (involuntary movements) | 43 | 8.4 6.2–11.3ROR 8.5 · χ² 272 / p 2e-61 | 7.9 EB05 6.0 · IC025 +2.4 3/3 methods agree | Likely indication confounding term in indications | serious PRR 7.0 | no trial data cached |
| Hypercholesterolaemia | 10 | 8.3 4.4–15.3ROR 8.3 · χ² 57 / p 3e-14 | 6.4 EB05 3.6 · IC025 +1.5 3/3 methods agree | Not in label — unassessed | serious PRR 5.4 | 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 |
|---|---|---|---|---|---|---|
| Completed suicide (death by suicide) | 132 | 12.4 10.5–14.6ROR 13.0 · χ² 1,375 / p <1e-300 | 12.3 EB05 10.6 · IC025 +3.3 3/3 methods agree | Outcome field, not a reaction | serious PRR 9.6 · 94% clinician | no trial data cached |
| Tremor (shaking) | 126 | 6.0 5.0–7.1ROR 6.2 · χ² 522 / p 8e-116 | 5.9 EB05 5.0 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious PRR 6.1 | no trial data cached |
| Diabetes mellitus | 120 | 12.4 10.4–14.8ROR 12.9 · χ² 1,247 / p 2e-273 | 12.3 EB05 10.5 · IC025 +3.3 3/3 methods agree | Not in label — unassessed | serious PRR 9.3 | no trial data cached |
| Drug interaction | 119 | 5.9 5.0–7.1ROR 6.2 · χ² 485 / p 8e-108 | 5.8 EB05 5.0 · IC025 +2.2 3/3 methods agree | Reporting / coding artifact | serious PRR 4.8 | no trial data cached |
| Weight increased (weight gain) | 110 | 3.9 3.2–4.7ROR 4.0 · χ² 237 / p 1e-53 | 3.8 EB05 3.3 · IC025 +1.6 3/3 methods agree | Labeled (related wording) related wording | serious PRR 4.6 | no trial data cached |
| Confusional state (confusion) | 104 | 5.1 4.2–6.1ROR 5.2 · χ² 338 / p 7e-76 | 5.0 EB05 4.2 · IC025 +2.0 3/3 methods agree | Labeled (related wording) related wording | serious PRR 4.5 | no trial data cached |
| Type 2 diabetes mellitus | 94 | 22.0 18.1–26.9ROR 22.8 · χ² 1,863 / p <1e-300 | 21.9 EB05 18.4 · IC025 +4.0 3/3 methods agree | Not in label — unassessed | serious PRR 15.2 | no trial data cached |
| Overdose | 76 | 2.8 2.2–3.5ROR 2.8 · χ² 85 / p 1e-20 | 2.7 EB05 2.3 · IC025 +1.1 3/3 methods agree | Reporting / coding artifact | serious PRR 2.5 | no trial data cached |
| Tardive dyskinesia (persistent involuntary movements) | 62 | 17.2 13.5–22.0ROR 17.6 · χ² 930 / p 2e-204 | 17.1 EB05 13.8 · IC025 +3.5 3/3 methods agree | Likely indication confounding term in indications | serious PRR 14.6 | no trial data cached |
| Toxicity to various agents | 61 | 2.9 2.2–3.7ROR 2.9 · χ² 73 / p 7e-18 | 2.8 EB05 2.3 · IC025 +1.1 3/3 methods agree | Not in label — unassessed | serious PRR 2.3 | no trial data cached |
| Leukopenia (low white blood cells) | 60 | 9.5 7.4–12.2ROR 9.7 · χ² 448 / p 8e-100 | 9.2 EB05 7.3 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious PRR 6.3 | no trial data cached |
| Psychotic disorder | 57 | 15.3 11.8–19.7ROR 15.6 · χ² 745 / p 3e-164 | 15.1 EB05 12.0 · IC025 +3.3 3/3 methods agree | Labeled (related wording) related wording | serious PRR 12.6 | no trial data cached |
| Suicidal ideation (thoughts of suicide) | 53 | 4.6 3.5–6.0ROR 4.6 · χ² 145 / p 1e-33 | 4.4 EB05 3.5 · IC025 +1.7 3/3 methods agree | Not in label — unassessed | serious PRR 3.7 | no trial data cached |
| Mental disorder | 51 | 9.2 7.0–12.1ROR 9.4 · χ² 367 / p 4e-82 | 8.8 EB05 6.9 · IC025 +2.6 3/3 methods agree | Labeled (related wording) related wording | serious PRR 8.3 | no trial data cached |
| Dystonia | 50 | 20.3 15.4–26.8ROR 20.7 · χ² 898 / p 1e-197 | 20.1 EB05 15.9 · IC025 +3.6 3/3 methods agree | Not in label — unassessed | serious PRR 16.3 | 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.
- Schizophrenia — n=44, PRR 28.7
- Neuroleptic malignant syndrome — n=39, PRR 26.0
- Hyperlipidaemia — n=39, PRR 25.8
- Type 2 diabetes mellitus — n=94, PRR 22.0
- Dystonia — n=50, PRR 20.3
- Sinus tachycardia — n=34, PRR 19.0
- Drug withdrawal syndrome neonatal — n=34, PRR 18.0
- Myocarditis — n=25, PRR 17.5
- Hallucination, auditory — n=35, PRR 17.4
- Muscle rigidity — n=24, PRR 15.9
✓ A hand-written Bradford Hill causality assessment exists for this drug: Benztropine ↔ Dry mouth.
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 Benztropine?
In FDA FAERS, the most frequently co-reported reaction terms for Benztropine are tremor, diabetes mellitus, weight increased, confusional state, type 2 diabetes mellitus, tardive dyskinesia. 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 Benztropine have an FDA boxed warning?
No. The FDA label retrieved for Benztropine has no boxed warning; see the label's Warnings and Precautions for the recognised risks.
Do FAERS signals prove that Benztropine 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 3d2732f9-b8a9-4e83-91e7-da616ddcb786, effective 20200501; matched on
openfda.generic_name.exact:"BENZTROPINE") - 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, 191 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.