Drug · FAERS side-effect profile with label screen
Carbidopa side effects: what 2,984 FDA adverse event reports show
Drug class
Aromatic Amino Acid Decarboxylation Inhibitor
FDA label (Established Pharmacologic Class)
Who reports
2,984 reports · 61% serious · 455 with death outcome · 45% female
openFDA FAERS counts, all years, deduplication not applied
Used for
Carbidopa tablets are indicated for use with carbidopa-levodopa or with levodopa in the treatment of the symptoms of idiopathic Parkinson's disease (paralysis agitans), postencephalitic parkinsonism, and symptomatic parkinsonism, which may follow injury to the nervous system by carbon monoxide intoxication and/or manganese intoxication.
FDA label, Indications and Usage
What it is
DESCRIPTION Carbidopa, an inhibitor of aromatic amino acid decarboxylation, is a white, crystalline compound, slightly soluble in water, with a molecular weight of 244.3. It is designated chemically as (–)-L-α-hydrazino-α-methyl-β-(3,4-dihydroxybenzene) propanoic acid monohydrate.
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 8Labeled (related wording) 3Likely indication confounding 1Reporting / coding artifact 2Not in label — unassessed 26
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.
- 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. 140 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 |
|---|---|---|---|---|---|---|
| Hallucination, visual | 113 | 38.0 31.7–45.6ROR 39.5 · χ² 4,019 / p <1e-300 | 37.6 EB05 32.1 · IC025 +4.7 3/3 methods agree | Not in label — unassessed | serious PRR 30.2 | no trial data cached |
| Delusion | 65 | 29.6 23.3–37.7ROR 30.2 · χ² 1,762 / p <1e-300 | 29.3 EB05 23.8 · IC025 +4.2 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 19.0 | no trial data cached |
| Hallucination (hallucinations) | 294 | 27.7 24.8–30.8ROR 30.6 · χ² 7,524 / p <1e-300 | 27.5 EB05 25.0 · IC025 +4.5 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 18.5 · 71% consumer | no trial data cached |
| Muscle rigidity | 30 | 17.7 12.4–25.2ROR 17.8 · χ² 454 / p 4e-101 | 17.4 EB05 12.7 · IC025 +3.2 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 18.0 · ♀ 22% (drug 45%) | no trial data cached |
| Parkinsonism | 24 | 17.3 11.6–25.8ROR 17.5 · χ² 352 / p 6e-79 | 17.0 EB05 11.8 · IC025 +3.0 3/3 methods agree | Likely indication confounding term in indications | serious PRR 18.8 · ♀ 67% (drug 45%) | no trial data cached |
| Dementia | 68 | 17.2 13.6–21.8ROR 17.6 · χ² 1,020 / p 4e-224 | 17.1 EB05 13.9 · IC025 +3.5 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 16.1 | no trial data cached |
| Ileus | 30 | 17.2 12.0–24.5ROR 17.3 · χ² 440 / p 6e-98 | 16.9 EB05 12.3 · IC025 +3.2 3/3 methods agree | Not in label — unassessed | serious PRR 16.2 · ♀ 100% (drug 45%) · 100% clinician | no trial data cached |
| Dyskinesia (involuntary movements) | 97 | 16.8 13.8–20.5ROR 17.4 · χ² 1,429 / p <1e-300 | 16.7 EB05 14.1 · IC025 +3.6 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 12.4 | no trial data cached |
| Orthostatic hypotension (dizziness on standing) | 29 | 11.7 8.1–16.8ROR 11.8 · χ² 273 / p 1e-61 | 11.1 EB05 7.8 · IC025 +2.7 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 10.3 · ♀ 12% (drug 45%) | no trial data cached |
| Hypokinesia | 24 | 11.6 7.8–17.3ROR 11.7 · χ² 222 / p 1e-50 | 10.9 EB05 7.3 · IC025 +2.6 3/3 methods agree | Not in label — unassessed | serious PRR 11.7 · ♀ 74% (drug 45%) | no trial data cached |
| Bladder disorder | 16 | 11.3 6.9–18.4ROR 11.4 · χ² 140 / p 1e-32 | 10.1 EB05 6.1 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious n=15 | no trial data cached |
| Neuroleptic malignant syndrome | 19 | 11.2 7.2–17.6ROR 11.3 · χ² 167 / p 2e-38 | 10.2 EB05 6.5 · IC025 +2.4 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 10.6 | no trial data cached |
| Hip fracture | 46 | 10.1 7.6–13.4ROR 10.2 · χ² 367 / p 4e-82 | 9.6 EB05 7.4 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious PRR 9.6 | no trial data cached |
| Product administration error | 28 | 9.9 6.8–14.3ROR 10.0 · χ² 214 / p 8e-49 | 9.1 EB05 6.4 · IC025 +2.5 3/3 methods agree | Reporting / coding artifact | serious PRR 21.1 · ♀ 100% (drug 45%) | no trial data cached |
| Device occlusion | 19 | 9.6 6.1–15.0ROR 9.7 · χ² 138 / p 4e-32 | 8.5 EB05 5.5 · IC025 +2.2 3/3 methods agree | Reporting / coding artifact | serious n=5 | no trial data cached |
| Serotonin syndrome | 24 | 8.8 5.9–13.1ROR 8.9 · χ² 159 / p 1e-36 | 7.9 EB05 5.5 · IC025 +2.2 3/3 methods agree | Not in label — unassessed | serious PRR 8.4 · 100% clinician | no trial data cached |
| Salivary hypersecretion | 12 | 8.4 4.8–14.9ROR 8.5 · χ² 71 / p 1e-17 | 6.8 EB05 4.0 · IC025 +1.7 3/3 methods agree | Not in label — unassessed | serious PRR 6.3 | no trial data cached |
| Personality change | 11 | 8.3 4.6–14.9ROR 8.3 · χ² 63 / p 9e-16 | 6.6 EB05 3.8 · IC025 +1.6 3/3 methods agree | Not in label — unassessed | serious PRR 8.6 | no trial data cached |
| Prescribed underdose | 23 | 8.1 5.4–12.2ROR 8.2 · χ² 136 / p 9e-32 | 7.2 EB05 5.0 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious PRR 5.1 | no trial data cached |
| Hypersomnia | 32 | 7.9 5.6–11.1ROR 7.9 · χ² 185 / p 2e-42 | 7.2 EB05 5.3 · IC025 +2.2 3/3 methods agree | Not in label — unassessed | serious PRR 9.7 | no trial data cached |
| Abnormal behaviour | 41 | 7.2 5.3–9.8ROR 7.3 · χ² 214 / p 9e-49 | 6.8 EB05 5.2 · IC025 +2.2 3/3 methods agree | Not in label — unassessed | serious PRR 5.5 | no trial data cached |
| Dystonia | 20 | 7.2 4.7–11.2ROR 7.3 · χ² 101 / p 4e-24 | 6.3 EB05 4.3 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 6.4 | no trial data cached |
| Myoclonus | 12 | 7.1 4.0–12.4ROR 7.1 · χ² 57 / p 3e-14 | 5.8 EB05 3.5 · IC025 +1.5 3/3 methods agree | Not in label — unassessed | serious PRR 5.3 | no trial data cached |
| Restless legs syndrome | 18 | 7.0 4.4–11.0ROR 7.0 · χ² 86 / p 1e-20 | 6.0 EB05 4.0 · IC025 +1.8 3/3 methods agree | Not in label — unassessed | serious PRR 6.5 | no trial data cached |
| Dysstasia | 28 | 6.7 4.6–9.7ROR 6.8 · χ² 131 / p 1e-30 | 6.1 EB05 4.4 · IC025 +2.0 3/3 methods agree | Not in label — unassessed | serious PRR 6.3 | no trial data cached |
| Oral discomfort | 13 | 6.6 3.8–11.3ROR 6.6 · χ² 56 / p 4e-14 | 5.5 EB05 3.4 · IC025 +1.5 3/3 methods agree | Not in label — unassessed | serious n=12 | no trial data cached |
| Paranoia | 16 | 6.5 4.0–10.6ROR 6.5 · χ² 69 / p 5e-17 | 5.6 EB05 3.6 · IC025 +1.6 3/3 methods agree | Not in label — unassessed | serious PRR 6.2 | no trial data cached |
| Gait inability | 30 | 6.4 4.5–9.1ROR 6.4 · χ² 131 / p 2e-30 | 5.8 EB05 4.3 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 6.0 · 80% consumer | no trial data cached |
| Confusional state (confusion) | 145 | 6.3 5.4–7.4ROR 6.6 · χ² 645 / p 1e-142 | 6.2 EB05 5.4 · IC025 +2.4 3/3 methods agree | Labeled (related wording) related wording | serious PRR 4.9 | no trial data cached |
| Speech disorder | 46 | 6.2 4.6–8.2ROR 6.3 · χ² 195 / p 2e-44 | 5.8 EB05 4.5 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious PRR 5.6 | no trial data cached |
| Skin haemorrhage | 12 | 5.8 3.3–10.3ROR 5.9 · χ² 43 / p 2e-11 | 4.9 EB05 3.0 · IC025 +1.3 3/3 methods agree | Not in label — unassessed | serious n=9 | no trial data cached |
| Disorientation | 33 | 5.8 4.2–8.2ROR 5.9 · χ² 128 / p 7e-30 | 5.4 EB05 4.0 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 5.5 | no trial data cached |
| Head injury | 26 | 5.8 3.9–8.5ROR 5.8 · χ² 98 / p 2e-23 | 5.3 EB05 3.8 · IC025 +1.8 3/3 methods agree | Not in label — unassessed | serious PRR 6.0 · ♀ 65% (drug 45%) · 75% consumer | no trial data cached |
| Nightmare | 28 | 5.7 3.9–8.2ROR 5.7 · χ² 103 / p 2e-24 | 5.2 EB05 3.8 · IC025 +1.8 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 5.2 · 74% consumer | no trial data cached |
| Cognitive disorder | 37 | 5.6 4.1–7.7ROR 5.6 · χ² 135 / p 2e-31 | 5.2 EB05 4.0 · IC025 +1.8 3/3 methods agree | Not in label — unassessed | serious PRR 6.6 | no trial data cached |
| Abnormal dreams | 22 | 5.6 3.7–8.4ROR 5.6 · χ² 78 / p 5e-19 | 5.0 EB05 3.5 · IC025 +1.6 3/3 methods agree | Not in label — unassessed | serious PRR 6.8 | no trial data cached |
| Tremor (shaking) | 131 | 5.5 4.7–6.5ROR 5.7 · χ² 486 / p 5e-108 | 5.4 EB05 4.7 · IC025 +2.2 3/3 methods agree | Not in label — unassessed | serious PRR 5.2 | no trial data cached |
| Psychotic disorder | 23 | 5.5 3.6–8.2ROR 5.5 · χ² 80 / p 2e-19 | 5.0 EB05 3.5 · IC025 +1.6 3/3 methods agree | Labeled (related wording) related wording | serious PRR 4.6 · ♀ 10% (drug 45%) | no trial data cached |
| Mania | 12 | 5.1 2.9–9.0ROR 5.1 · χ² 36 / p 1e-9 | 4.4 EB05 2.7 · IC025 +1.2 3/3 methods agree | Not in label — unassessed | serious PRR 6.0 | no trial data cached |
| Blood pressure decreased | 48 | 5.1 3.8–6.7ROR 5.2 · χ² 154 / p 1e-35 | 4.9 EB05 3.8 · IC025 +1.8 3/3 methods agree | Labeled (related wording) related wording | serious PRR 3.2 · 70% consumer | 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 |
|---|---|---|---|---|---|---|
| Hallucination (hallucinations) | 294 | 27.7 24.8–30.8ROR 30.6 · χ² 7,524 / p <1e-300 | 27.5 EB05 25.0 · IC025 +4.5 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 18.5 · 71% consumer | no trial data cached |
| Death | 240 | 2.0 1.7–2.2ROR 2.0 · χ² 116 / p 2e-27 | 2.0 EB05 1.8 · IC025 +0.8 | Outcome field, not a reaction | serious PRR 1.8 | no trial data cached |
| Fall | 239 | 5.1 4.5–5.7ROR 5.4 · χ² 785 / p 5e-173 | 5.0 EB05 4.5 · IC025 +2.1 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 4.6 | no trial data cached |
| Confusional state (confusion) | 145 | 6.3 5.4–7.4ROR 6.6 · χ² 645 / p 1e-142 | 6.2 EB05 5.4 · IC025 +2.4 3/3 methods agree | Labeled (related wording) related wording | serious PRR 4.9 | no trial data cached |
| Tremor (shaking) | 131 | 5.5 4.7–6.5ROR 5.7 · χ² 486 / p 5e-108 | 5.4 EB05 4.7 · IC025 +2.2 3/3 methods agree | Not in label — unassessed | serious PRR 5.2 | no trial data cached |
| Somnolence (drowsiness) | 121 | 4.2 3.6–5.0ROR 4.4 · χ² 298 / p 5e-67 | 4.2 EB05 3.6 · IC025 +1.8 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 3.6 | no trial data cached |
| Gait disturbance | 121 | 4.4 3.7–5.3ROR 4.6 · χ² 321 / p 5e-72 | 4.4 EB05 3.7 · IC025 +1.8 3/3 methods agree | Not in label — unassessed | serious PRR 4.1 · 73% consumer | no trial data cached |
| Product dose omission issue | 119 | 2.9 2.5–3.5ROR 3.0 · χ² 152 / p 3e-35 | 2.9 EB05 2.5 · IC025 +1.2 3/3 methods agree | Reporting / coding artifact | serious PRR 4.9 · 78% consumer | no trial data cached |
| Hallucination, visual | 113 | 38.0 31.7–45.6ROR 39.5 · χ² 4,019 / p <1e-300 | 37.6 EB05 32.1 · IC025 +4.7 3/3 methods agree | Not in label — unassessed | serious PRR 30.2 | no trial data cached |
| Urinary tract infection (bladder infection) | 98 | 4.0 3.3–4.9ROR 4.2 · χ² 224 / p 7e-51 | 4.0 EB05 3.4 · IC025 +1.7 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 4.0 | no trial data cached |
| Dyskinesia (involuntary movements) | 97 | 16.8 13.8–20.5ROR 17.4 · χ² 1,429 / p <1e-300 | 16.7 EB05 14.1 · IC025 +3.6 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 12.4 | no trial data cached |
| Memory impairment | 72 | 3.7 2.9–4.6ROR 3.7 · χ² 139 / p 3e-32 | 3.6 EB05 3.0 · IC025 +1.5 3/3 methods agree | Not in label — unassessed | serious PRR 3.7 · 71% consumer | no trial data cached |
| Dementia | 68 | 17.2 13.6–21.8ROR 17.6 · χ² 1,020 / p 4e-224 | 17.1 EB05 13.9 · IC025 +3.5 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 16.1 | no trial data cached |
| Delusion | 65 | 29.6 23.3–37.7ROR 30.2 · χ² 1,762 / p <1e-300 | 29.3 EB05 23.8 · IC025 +4.2 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 19.0 | no trial data cached |
| Balance disorder | 56 | 4.5 3.5–5.9ROR 4.6 · χ² 152 / p 3e-35 | 4.4 EB05 3.5 · IC025 +1.7 3/3 methods agree | Not in label — unassessed | serious PRR 3.9 | 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.
- Hallucination, visual — n=113, PRR 38.0
- Ileus — n=30, PRR 17.2
- Hypokinesia — n=24, PRR 11.6
- Hip fracture — n=46, PRR 10.1
- Serotonin syndrome — n=24, PRR 8.8
- Prescribed underdose — n=23, PRR 8.1
- Hypersomnia — n=32, PRR 7.9
- Abnormal behaviour — n=41, PRR 7.2
- Dystonia — n=20, PRR 7.2
- Dysstasia — n=28, PRR 6.7
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 Carbidopa?
In FDA FAERS, the most frequently co-reported reaction terms for Carbidopa are hallucination, fall, confusional state, tremor, somnolence, gait disturbance. 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 Carbidopa have an FDA boxed warning?
No. The FDA label retrieved for Carbidopa has no boxed warning; see the label's Warnings and Precautions for the recognised risks.
Do FAERS signals prove that Carbidopa 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 55b99f22-9eb2-4df6-9979-bc4c3af5e454, effective 20251217; matched on
openfda.generic_name.exact:"CARBIDOPA") - 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, 180 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.