Meclizine HCL side effects: what 2,177 FDA adverse event reports show
Drug class
Not stated in label
Brand names
Meclizine Hydrochloride
Who reports
2,177 reports · 52% serious · 165 with death outcome · 73% female
Used for
Meclizine hydrochloride tablets are indicated for the treatment of vertigo associated with diseases affecting the vestibular system in adults. Meclizine hydrochloride tablets are indicated for the treatment of vertigo associated with diseases affecting the vestibular system in adults ( 1 ).
What it is
Meclizine hydrochloride, USP a histamine (H1) receptor antagonist, is a white to slight yellowish crystalline powder. It has the following structural formula:
Boxed warning
None in the current label
Causality screen of the 28 strongest signals
What the badges mean
- 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. 39 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 |
|---|---|---|---|---|---|---|
| Vertigo (spinning dizziness) | 63 | 10.0 7.8–12.7ROR 10.2 · χ² 500 / p 5e-111 | 9.6 EB05 7.7 · IC025 +2.8 3/3 methods agree | Likely indication confounding term in indications | serious PRR 9.0 | no trial data cached |
| Hospice care | 10 | 9.8 5.3–18.2ROR 9.8 · χ² 70 / p 3e-17 | 7.7 EB05 4.2 · IC025 +1.7 3/3 methods agree | Not in label — unassessed | serious PRR 7.8 | no trial data cached |
| End stage renal disease | 17 | 8.9 5.5–14.3ROR 9.0 · χ² 111 / p 2e-26 | 7.7 EB05 4.9 · IC025 +2.0 3/3 methods agree | Not in label — unassessed | serious PRR 9.8 | no trial data cached |
| Economic problem | 14 | 8.8 5.2–14.8ROR 8.8 · χ² 89 / p 2e-21 | 7.3 EB05 4.4 · IC025 +1.9 3/3 methods agree | Reporting / coding artifact | serious PRR 10.6 | no trial data cached |
| Full blood count decreased | 17 | 8.1 5.1–13.1ROR 8.2 · χ² 99 / p 1e-23 | 7.0 EB05 4.5 · IC025 +1.9 3/3 methods agree | Lab value / disease marker | serious PRR 9.2 | no trial data cached |
| Chronic kidney disease | 59 | 7.4 5.8–9.5ROR 7.6 · χ² 322 / p 2e-72 | 7.1 EB05 5.7 · IC025 +2.4 3/3 methods agree | Not in label — unassessed | serious PRR 8.3 | no trial data cached |
| Anhedonia | 19 | 6.9 4.4–10.8ROR 7.0 · χ² 90 / p 1e-21 | 6.0 EB05 4.0 · IC025 +1.8 3/3 methods agree | Not in label — unassessed | serious PRR 8.5 | no trial data cached |
| Blood count abnormal | 11 | 6.9 3.8–12.4ROR 6.9 · χ² 50 / p 9e-13 | 5.5 EB05 3.3 · IC025 +1.4 3/3 methods agree | Lab value / disease marker | serious PRR 4.8 | no trial data cached |
| Seasonal allergy | 10 | 6.8 3.7–12.7ROR 6.9 · χ² 44 / p 2e-11 | 5.4 EB05 3.1 · IC025 +1.3 3/3 methods agree | Not in label — unassessed | serious n=4 | no trial data cached |
| Rib fracture | 14 | 6.6 3.9–11.1ROR 6.6 · χ² 61 / p 3e-15 | 5.5 EB05 3.5 · IC025 +1.6 3/3 methods agree | Not in label — unassessed | serious PRR 6.8 | no trial data cached |
| Multiple sclerosis relapse | 45 | 6.3 4.7–8.4ROR 6.4 · χ² 195 / p 1e-44 | 5.9 EB05 4.6 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious PRR 8.6 · 77% consumer | no trial data cached |
| Multiple sclerosis | 31 | 6.2 4.4–8.8ROR 6.3 · χ² 131 / p 1e-30 | 5.7 EB05 4.2 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 6.3 · 77% consumer | no trial data cached |
| Product dose omission | 40 | 5.8 4.3–7.9ROR 5.9 · χ² 155 / p 6e-36 | 5.5 EB05 4.2 · IC025 +1.9 3/3 methods agree | Reporting / coding artifact | serious PRR 8.5 · 72% consumer | no trial data cached |
| Head injury | 19 | 5.8 3.7–9.1ROR 5.8 · χ² 71 / p 2e-17 | 5.1 EB05 3.5 · IC025 +1.6 3/3 methods agree | Not in label — unassessed | serious PRR 5.1 | no trial data cached |
| Localised infection | 14 | 5.6 3.3–9.4ROR 5.6 · χ² 48 / p 2e-12 | 4.8 EB05 3.0 · IC025 +1.4 3/3 methods agree | Not in label — unassessed | serious PRR 6.3 | no trial data cached |
| Urinary incontinence | 17 | 5.5 3.4–8.9ROR 5.6 · χ² 59 / p 9e-15 | 4.9 EB05 3.2 · IC025 +1.5 3/3 methods agree | Not in label — unassessed | serious PRR 6.3 | no trial data cached |
| Balance disorder | 48 | 5.3 4.0–7.1ROR 5.4 · χ² 166 / p 3e-38 | 5.1 EB05 4.0 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 5.7 | no trial data cached |
| Fall | 162 | 4.7 4.0–5.4ROR 5.0 · χ² 475 / p 1e-105 | 4.6 EB05 4.1 · IC025 +2.0 3/3 methods agree | Not in label — unassessed | serious PRR 4.7 | no trial data cached |
| Memory impairment | 60 | 4.2 3.3–5.4ROR 4.3 · χ² 144 / p 2e-33 | 4.1 EB05 3.3 · IC025 +1.6 3/3 methods agree | Not in label — unassessed | serious PRR 4.6 | no trial data cached |
| Therapeutic response unexpected | 18 | 3.9 2.4–6.1ROR 3.9 · χ² 35 / p 1e-9 | 3.5 EB05 2.4 · IC025 +1.0 3/3 methods agree | Reporting / coding artifact | serious PRR 4.6 | no trial data cached |
| Abasia | 10 | 3.8 2.1–7.1ROR 3.9 · χ² 18 / p 9e-6 | 3.3 EB05 2.0 · IC025 +0.7 | Not in label — unassessed | serious PRR 4.1 | no trial data cached |
| Therapy cessation | 20 | 3.8 2.4–5.8ROR 3.8 · χ² 38 / p 3e-10 | 3.5 EB05 2.4 · IC025 +1.1 3/3 methods agree | Reporting / coding artifact | serious PRR 5.1 | no trial data cached |
| Hallucination (hallucinations) | 28 | 3.6 2.5–5.2ROR 3.6 · χ² 50 / p 7e-13 | 3.4 EB05 2.5 · IC025 +1.2 3/3 methods agree | Not in label — unassessed | serious PRR 4.2 · ♀ 44% (drug 73%) | no trial data cached |
| Renal injury | 11 | 3.5 2.0–6.4ROR 3.5 · χ² 18 / p 1e-5 | 3.2 EB05 1.9 · IC025 +0.6 | Not in label — unassessed | serious PRR 3.9 | no trial data cached |
| Plasma cell myeloma | 13 | 3.2 1.9–5.5ROR 3.2 · χ² 18 / p 1e-5 | 2.9 EB05 1.9 · IC025 +0.6 | Not in label — unassessed | serious PRR 3.5 | no trial data cached |
| Completed suicide (death by suicide) | 24 | 2.7 1.8–4.1ROR 2.8 · χ² 25 / p 3e-7 | 2.6 EB05 1.9 · IC025 +0.7 | Outcome field, not a reaction | serious PRR 3.0 · 100% clinician | no trial data cached |
| Drug effect decreased | 12 | 2.1 1.2–3.7ROR 2.1 · χ² 6 / p 0.007 | 2.0 EB05 1.3 · IC025 +0.0 | Reporting / coding artifact | serious PRR 3.4 | no trial data cached |
| Emotional distress | 26 | 2.1 1.4–3.0ROR 2.1 · χ² 13 / p 1e-4 | 2.0 EB05 1.5 · IC025 +0.4 | Not in label — unassessed | serious PRR 2.6 · ♀ 43% (drug 73%) | no trial data cached |
Trial evidence (ClinicalTrials.gov)
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 | 162 | 4.7 4.0–5.4ROR 5.0 · χ² 475 / p 1e-105 | 4.6 EB05 4.1 · IC025 +2.0 3/3 methods agree | Not in label — unassessed | serious PRR 4.7 | no trial data cached |
| Vertigo (spinning dizziness) | 63 | 10.0 7.8–12.7ROR 10.2 · χ² 500 / p 5e-111 | 9.6 EB05 7.7 · IC025 +2.8 3/3 methods agree | Likely indication confounding term in indications | serious PRR 9.0 | no trial data cached |
| Memory impairment | 60 | 4.2 3.3–5.4ROR 4.3 · χ² 144 / p 2e-33 | 4.1 EB05 3.3 · IC025 +1.6 3/3 methods agree | Not in label — unassessed | serious PRR 4.6 | no trial data cached |
| Chronic kidney disease | 59 | 7.4 5.8–9.5ROR 7.6 · χ² 322 / p 2e-72 | 7.1 EB05 5.7 · IC025 +2.4 3/3 methods agree | Not in label — unassessed | serious PRR 8.3 | no trial data cached |
| Balance disorder | 48 | 5.3 4.0–7.1ROR 5.4 · χ² 166 / p 3e-38 | 5.1 EB05 4.0 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 5.7 | no trial data cached |
| Multiple sclerosis relapse | 45 | 6.3 4.7–8.4ROR 6.4 · χ² 195 / p 1e-44 | 5.9 EB05 4.6 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious PRR 8.6 · 77% consumer | no trial data cached |
| Product dose omission | 40 | 5.8 4.3–7.9ROR 5.9 · χ² 155 / p 6e-36 | 5.5 EB05 4.2 · IC025 +1.9 3/3 methods agree | Reporting / coding artifact | serious PRR 8.5 · 72% consumer | no trial data cached |
| Multiple sclerosis | 31 | 6.2 4.4–8.8ROR 6.3 · χ² 131 / p 1e-30 | 5.7 EB05 4.2 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 6.3 · 77% consumer | no trial data cached |
| Drug dose omission | 30 | 1.7 1.2–2.5ROR 1.7 · χ² 8 / p 0.002 | 1.7 EB05 1.3 · IC025 +0.2 | Reporting / coding artifact | serious PRR 4.6 | no trial data cached |
| Hallucination (hallucinations) | 28 | 3.6 2.5–5.2ROR 3.6 · χ² 50 / p 7e-13 | 3.4 EB05 2.5 · IC025 +1.2 3/3 methods agree | Not in label — unassessed | serious PRR 4.2 · ♀ 44% (drug 73%) | no trial data cached |
| Emotional distress | 26 | 2.1 1.4–3.0ROR 2.1 · χ² 13 / p 1e-4 | 2.0 EB05 1.5 · IC025 +0.4 | Not in label — unassessed | serious PRR 2.6 · ♀ 43% (drug 73%) | no trial data cached |
| Completed suicide (death by suicide) | 24 | 2.7 1.8–4.1ROR 2.8 · χ² 25 / p 3e-7 | 2.6 EB05 1.9 · IC025 +0.7 | Outcome field, not a reaction | serious PRR 3.0 · 100% clinician | no trial data cached |
| Therapy cessation | 20 | 3.8 2.4–5.8ROR 3.8 · χ² 38 / p 3e-10 | 3.5 EB05 2.4 · IC025 +1.1 3/3 methods agree | Reporting / coding artifact | serious PRR 5.1 | no trial data cached |
| Head injury | 19 | 5.8 3.7–9.1ROR 5.8 · χ² 71 / p 2e-17 | 5.1 EB05 3.5 · IC025 +1.6 3/3 methods agree | Not in label — unassessed | serious PRR 5.1 | no trial data cached |
| Anhedonia | 19 | 6.9 4.4–10.8ROR 7.0 · χ² 90 / p 1e-21 | 6.0 EB05 4.0 · IC025 +1.8 3/3 methods agree | Not in label — unassessed | serious PRR 8.5 | 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.
- Chronic kidney disease — n=59, PRR 7.4
- Multiple sclerosis relapse — n=45, PRR 6.3
- Multiple sclerosis — n=31, PRR 6.2
- Balance disorder — n=48, PRR 5.3
- Fall — n=162, PRR 4.7
- Memory impairment — n=60, PRR 4.2
- Hallucination — n=28, PRR 3.6
- Emotional distress — n=26, PRR 2.1
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 Meclizine?
In FDA FAERS, the most frequently co-reported reaction terms for Meclizine are fall, vertigo, memory impairment, chronic kidney disease, balance disorder, multiple sclerosis relapse. 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 Meclizine have an FDA boxed warning?
No. The FDA label retrieved for Meclizine has no boxed warning; see the label's Warnings and Precautions for the recognised risks.
Do FAERS signals prove that Meclizine 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 1079db3f-d8ad-4c25-aa91-8ac8054ee4f2, effective 20260608; matched on
openfda.generic_name.exact:"MECLIZINE") - 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, 67 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.