Drug · FAERS side-effect profile with label screen
Amantadine Hydrochloride side effects: what 4,855 FDA adverse event reports show
Drug class
Lower incidence of these side effects than
FDA label, Indications wording
Who reports
4,855 reports · 74% serious · 485 with death outcome · 60% female
openFDA FAERS counts, all years, deduplication not applied
Used for
Amantadine hydrochloride tablets are indicated for the prophylaxis and treatment of signs and symptoms of infection caused by various strains of influenza A virus. Amantadine hydrochloride tablets are also indicated in the treatment of parkinsonism and drug-induced extrapyramidal reactions.
FDA label, Indications and Usage
What it is
DESCRIPTION Amantadine hydrochloride, USP is designated generically as amantadine hydrochloride and chemically as 1-adamantanamine hydrochloride. Amantadine hydrochloride, USP is a stable white or practically white crystalline powder, freely soluble in water, soluble in alcohol and in chloroform.
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 9Labeled (related wording) 5Likely indication confounding 3Reporting / coding artifact 1Not in label — unassessed 22
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. 354 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 |
|---|---|---|---|---|---|---|
| Myoclonus | 77 | 28.0 22.4–35.0ROR 28.5 · χ² 1,969 / p <1e-300 | 27.7 EB05 22.9 · IC025 +4.2 3/3 methods agree | Not in label — unassessed | serious PRR 22.5 · 97% clinician | no trial data cached |
| Hallucination, visual | 134 | 27.7 23.4–32.8ROR 28.5 · χ² 3,406 / p <1e-300 | 27.5 EB05 23.8 · IC025 +4.4 3/3 methods agree | Labeled (related wording) related wording | serious PRR 21.8 | no trial data cached |
| Neuroleptic malignant syndrome | 67 | 24.4 19.3–31.0ROR 24.8 · χ² 1,475 / p <1e-300 | 24.2 EB05 19.7 · IC025 +4.0 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 18.9 · 91% clinician | no trial data cached |
| Dyskinesia (involuntary movements) | 197 | 21.1 18.4–24.1ROR 21.9 · χ² 3,732 / p <1e-300 | 20.9 EB05 18.6 · IC025 +4.1 3/3 methods agree | Not in label — unassessed | serious PRR 19.2 | no trial data cached |
| Delusion | 66 | 18.5 14.5–23.5ROR 18.7 · χ² 1,069 / p 1e-234 | 18.3 EB05 14.9 · IC025 +3.6 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 14.0 | no trial data cached |
| Parkinsonism | 40 | 17.8 13.0–24.2ROR 17.9 · χ² 614 / p 8e-136 | 17.5 EB05 13.4 · IC025 +3.3 3/3 methods agree | Likely indication confounding term in indications | serious PRR 15.4 | no trial data cached |
| Muscle rigidity | 45 | 16.3 12.2–21.8ROR 16.4 · χ² 629 / p 4e-139 | 16.1 EB05 12.4 · IC025 +3.3 3/3 methods agree | Not in label — unassessed | serious PRR 12.9 | no trial data cached |
| Mitral valve incompetence | 41 | 15.7 11.6–21.3ROR 15.8 · χ² 547 / p 2e-121 | 15.4 EB05 11.8 · IC025 +3.2 3/3 methods agree | Not in label — unassessed | serious PRR 12.2 | no trial data cached |
| Hallucination (hallucinations) | 254 | 14.7 13.0–16.5ROR 15.4 · χ² 3,221 / p <1e-300 | 14.6 EB05 13.1 · IC025 +3.6 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 11.5 | no trial data cached |
| Micturition urgency | 38 | 14.5 10.6–19.9ROR 14.6 · χ² 463 / p 5e-103 | 14.2 EB05 10.7 · IC025 +3.1 3/3 methods agree | Not in label — unassessed | serious PRR 16.1 · ♀ 16% (drug 60%) | no trial data cached |
| Speech disorder | 164 | 13.5 11.6–15.7ROR 14.0 · χ² 1,891 / p <1e-300 | 13.5 EB05 11.8 · IC025 +3.4 3/3 methods agree | Labeled (related wording) related wording | serious PRR 12.5 | no trial data cached |
| Multiple sclerosis | 132 | 11.9 10.0–14.1ROR 12.2 · χ² 1,304 / p 1e-285 | 11.8 EB05 10.1 · IC025 +3.2 3/3 methods agree | Not in label — unassessed | serious PRR 11.1 | no trial data cached |
| Multiple sclerosis relapse | 189 | 11.8 10.3–13.6ROR 12.3 · χ² 1,863 / p <1e-300 | 11.7 EB05 10.4 · IC025 +3.3 3/3 methods agree | Not in label — unassessed | serious PRR 10.5 | no trial data cached |
| Hallucination, auditory | 41 | 11.1 8.2–15.1ROR 11.2 · χ² 368 / p 3e-82 | 10.7 EB05 8.0 · IC025 +2.8 3/3 methods agree | Not in label — unassessed | serious PRR 8.0 | no trial data cached |
| Grand mal convulsion | 24 | 11.1 7.4–16.5ROR 11.1 · χ² 210 / p 8e-48 | 10.3 EB05 6.9 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious PRR 8.7 | no trial data cached |
| Dystonia | 49 | 10.9 8.2–14.4ROR 11.0 · χ² 429 / p 1e-95 | 10.5 EB05 8.1 · IC025 +2.8 3/3 methods agree | Not in label — unassessed | serious PRR 8.5 | no trial data cached |
| Nocturia (night-time urination) | 30 | 10.7 7.5–15.3ROR 10.8 · χ² 254 / p 2e-57 | 10.1 EB05 7.1 · IC025 +2.6 3/3 methods agree | Not in label — unassessed | serious PRR 14.2 · ♀ 10% (drug 60%) | no trial data cached |
| Inappropriate antidiuretic hormone secretion | 25 | 10.6 7.2–15.7ROR 10.7 · χ² 208 / p 2e-47 | 9.8 EB05 6.7 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious PRR 8.3 · ♀ 28% (drug 60%) · 90% clinician | no trial data cached |
| Delirium | 79 | 9.9 7.9–12.3ROR 10.0 · χ² 621 / p 2e-137 | 9.6 EB05 7.9 · IC025 +2.9 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 7.7 | no trial data cached |
| Psychotic disorder | 67 | 9.8 7.7–12.4ROR 9.9 · χ² 521 / p 2e-115 | 9.5 EB05 7.7 · IC025 +2.8 3/3 methods agree | Labeled (related wording) related wording | serious PRR 7.7 | no trial data cached |
| Dysarthria (slurred speech) | 84 | 9.7 7.8–11.9ROR 9.8 · χ² 643 / p 5e-142 | 9.4 EB05 7.8 · IC025 +2.8 3/3 methods agree | Not in label — unassessed | serious PRR 8.1 | no trial data cached |
| Motor dysfunction | 22 | 9.4 6.2–14.3ROR 9.4 · χ² 157 / p 3e-36 | 8.4 EB05 5.7 · IC025 +2.3 3/3 methods agree | Labeled (related wording) related wording | serious PRR 8.3 | no trial data cached |
| Balance disorder | 177 | 8.8 7.6–10.2ROR 9.1 · χ² 1,225 / p 1e-268 | 8.7 EB05 7.7 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious PRR 8.0 | no trial data cached |
| Feeling cold | 57 | 8.8 6.8–11.4ROR 8.9 · χ² 388 / p 1e-86 | 8.4 EB05 6.7 · IC025 +2.6 3/3 methods agree | Not in label — unassessed | serious PRR 11.1 · ♀ 9% (drug 60%) | no trial data cached |
| Orthostatic hypotension (dizziness on standing) | 35 | 8.7 6.2–12.1ROR 8.7 · χ² 230 / p 4e-52 | 8.1 EB05 6.0 · IC025 +2.4 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 6.5 | no trial data cached |
| Aspiration | 21 | 8.4 5.5–12.8ROR 8.4 · χ² 129 / p 3e-30 | 7.4 EB05 5.0 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious PRR 6.3 | no trial data cached |
| Ataxia | 23 | 8.3 5.5–12.5ROR 8.4 · χ² 141 / p 7e-33 | 7.4 EB05 5.1 · IC025 +2.2 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 6.4 | no trial data cached |
| Diplopia (double vision) | 46 | 7.7 5.7–10.2ROR 7.7 · χ² 259 / p 1e-58 | 7.2 EB05 5.6 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious PRR 7.9 · ♀ 38% (drug 60%) | no trial data cached |
| Convulsion (seizure) | 102 | 7.6 6.3–9.2ROR 7.7 · χ² 579 / p 4e-128 | 7.4 EB05 6.2 · IC025 +2.6 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 6.0 | no trial data cached |
| Economic problem | 27 | 7.6 5.2–11.0ROR 7.6 · χ² 147 / p 3e-34 | 6.9 EB05 4.9 · IC025 +2.1 3/3 methods agree | Reporting / coding artifact | serious PRR 5.0 | no trial data cached |
| Drug toxicity | 24 | 7.5 5.0–11.2ROR 7.5 · χ² 129 / p 4e-30 | 6.7 EB05 4.7 · IC025 +2.0 3/3 methods agree | Labeled (related wording) related wording | serious PRR 5.8 · ♀ 83% (drug 60%) · 95% clinician | no trial data cached |
| Mental status changes | 47 | 7.3 5.5–9.7ROR 7.4 · χ² 249 / p 2e-56 | 6.9 EB05 5.4 · IC025 +2.3 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious PRR 6.1 · ♀ 38% (drug 60%) | no trial data cached |
| Paranoia | 29 | 7.2 5.0–10.4ROR 7.3 · χ² 149 / p 1e-34 | 6.6 EB05 4.8 · IC025 +2.1 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 6.1 · ♀ 31% (drug 60%) | no trial data cached |
| Encephalopathy | 41 | 7.2 5.3–9.8ROR 7.3 · χ² 214 / p 1e-48 | 6.8 EB05 5.2 · IC025 +2.2 3/3 methods agree | Not in label — unassessed | serious PRR 5.6 | no trial data cached |
| Serotonin syndrome | 32 | 7.2 5.1–10.2ROR 7.3 · χ² 165 / p 4e-38 | 6.6 EB05 4.9 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious PRR 5.6 · 100% clinician | no trial data cached |
| Pneumonia aspiration | 41 | 7.1 5.2–9.6ROR 7.2 · χ² 209 / p 1e-47 | 6.6 EB05 5.1 · IC025 +2.2 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious PRR 5.5 | no trial data cached |
| Cognitive disorder | 75 | 7.0 5.6–8.7ROR 7.1 · χ² 377 / p 2e-84 | 6.7 EB05 5.5 · IC025 +2.4 3/3 methods agree | Not in label — unassessed | serious PRR 6.7 | no trial data cached |
| Incontinence | 17 | 6.9 4.3–11.1ROR 7.0 · χ² 80 / p 2e-19 | 6.0 EB05 3.9 · IC025 +1.7 3/3 methods agree | Not in label — unassessed | serious PRR 6.4 | no trial data cached |
| Hypokinesia | 23 | 6.8 4.5–10.3ROR 6.9 · χ² 109 / p 9e-26 | 6.1 EB05 4.3 · IC025 +1.9 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 5.3 | no trial data cached |
| Dysstasia | 46 | 6.8 5.1–9.0ROR 6.8 · χ² 221 / p 3e-50 | 6.4 EB05 5.0 · IC025 +2.2 3/3 methods agree | Not in label — unassessed | serious PRR 6.0 | 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 |
|---|---|---|---|---|---|---|
| Fall | 392 | 5.1 4.6–5.6ROR 5.5 · χ² 1,304 / p 7e-286 | 5.1 EB05 4.7 · IC025 +2.2 3/3 methods agree | Not in label — unassessed | serious PRR 3.8 | no trial data cached |
| Gait disturbance | 288 | 6.5 5.8–7.3ROR 6.8 · χ² 1,340 / p 1e-293 | 6.4 EB05 5.8 · IC025 +2.5 3/3 methods agree | Labeled (related wording) related wording | serious PRR 5.6 | no trial data cached |
| Hallucination (hallucinations) | 254 | 14.7 13.0–16.5ROR 15.4 · χ² 3,221 / p <1e-300 | 14.6 EB05 13.1 · IC025 +3.6 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 11.5 | no trial data cached |
| Tremor (shaking) | 222 | 5.8 5.1–6.6ROR 6.0 · χ² 876 / p 8e-193 | 5.7 EB05 5.1 · IC025 +2.3 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 5.6 | no trial data cached |
| Depression | 213 | 4.0 3.5–4.6ROR 4.2 · χ² 486 / p 5e-108 | 4.0 EB05 3.6 · IC025 +1.8 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 3.3 | no trial data cached |
| Asthenia (weakness) | 212 | 2.4 2.1–2.8ROR 2.5 · χ² 181 / p 2e-41 | 2.4 EB05 2.2 · IC025 +1.1 3/3 methods agree | Not in label — unassessed | serious PRR 2.1 | no trial data cached |
| Dyskinesia (involuntary movements) | 197 | 21.1 18.4–24.1ROR 21.9 · χ² 3,732 / p <1e-300 | 20.9 EB05 18.6 · IC025 +4.1 3/3 methods agree | Not in label — unassessed | serious PRR 19.2 | no trial data cached |
| Multiple sclerosis relapse | 189 | 11.8 10.3–13.6ROR 12.3 · χ² 1,863 / p <1e-300 | 11.7 EB05 10.4 · IC025 +3.3 3/3 methods agree | Not in label — unassessed | serious PRR 10.5 | no trial data cached |
| Balance disorder | 177 | 8.8 7.6–10.2ROR 9.1 · χ² 1,225 / p 1e-268 | 8.7 EB05 7.7 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious PRR 8.0 | no trial data cached |
| Condition aggravated | 168 | 2.4 2.1–2.8ROR 2.5 · χ² 138 / p 4e-32 | 2.4 EB05 2.1 · IC025 +1.0 3/3 methods agree | Reporting / coding artifact | serious PRR 2.4 | no trial data cached |
| Urinary tract infection (bladder infection) | 167 | 4.2 3.7–4.9ROR 4.4 · χ² 413 / p 4e-92 | 4.2 EB05 3.7 · IC025 +1.8 3/3 methods agree | Not in label — unassessed | serious PRR 3.8 | no trial data cached |
| Speech disorder | 164 | 13.5 11.6–15.7ROR 14.0 · χ² 1,891 / p <1e-300 | 13.5 EB05 11.8 · IC025 +3.4 3/3 methods agree | Labeled (related wording) related wording | serious PRR 12.5 | no trial data cached |
| Constipation | 161 | 3.2 2.8–3.7ROR 3.3 · χ² 245 / p 1e-55 | 3.2 EB05 2.8 · IC025 +1.4 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 3.7 · ♀ 38% (drug 60%) | no trial data cached |
| Confusional state (confusion) | 159 | 4.2 3.6–4.9ROR 4.3 · χ² 393 / p 9e-88 | 4.2 EB05 3.7 · IC025 +1.8 3/3 methods agree | Labeled (related wording) related wording | serious PRR 3.6 | no trial data cached |
| Insomnia (trouble sleeping) | 155 | 2.5 2.1–2.9ROR 2.6 · χ² 141 / p 9e-33 | 2.5 EB05 2.2 · IC025 +1.1 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.4 | 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.
- Myoclonus — n=77, PRR 28.0
- Dyskinesia — n=197, PRR 21.1
- Muscle rigidity — n=45, PRR 16.3
- Mitral valve incompetence — n=41, PRR 15.7
- Micturition urgency — n=38, PRR 14.5
- Multiple sclerosis — n=132, PRR 11.9
- Multiple sclerosis relapse — n=189, PRR 11.8
- Hallucination, auditory — n=41, PRR 11.1
- Grand mal convulsion — n=24, PRR 11.1
- Dystonia — n=49, PRR 10.9
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 Amantadine?
In FDA FAERS, the most frequently co-reported reaction terms for Amantadine are fall, gait disturbance, hallucination, tremor, depression, asthenia. 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 Amantadine have an FDA boxed warning?
No. The FDA label retrieved for Amantadine has no boxed warning; see the label's Warnings and Precautions for the recognised risks.
Do FAERS signals prove that Amantadine 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 2ff05131-f634-4688-86e9-9bc33a8d11c4, effective 20260123; matched on
openfda.generic_name.exact:"AMANTADINE") - 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, 394 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.