Meclizine side effects: what 16,219 FDA adverse event reports show

Meclizine · Meclizine Hydrochloride · 1,151 reaction terms · 78,271 drug–reaction co-reports · data 2026-09-14

Drug class

Not stated in label

Brand names

Meclizine Hydrochloride

openFDA label

Who reports

16,219 reports · 63% serious · 1,456 with death outcome · 74% female

openFDA FAERS counts, all years, deduplication not applied

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 ).

FDA label, Indications and Usage

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:

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

Likely indication confounding 2Reporting / coding artifact 1Lab value / disease marker 1Not in label — unassessed 36

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.
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. 1,111 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.

Show: hide coding/lab/outcome terms hide indication terms unlabeled only hide PRR-only

Reaction	Reports	PRR 95% CI · ROR · χ²/p	EBGM EB05 · IC025	Label screen	Serious-only & strata	Trial cross-check
Narcotic bowel syndrome	16	147.7 88.0–247.8ROR 147.9 · χ² 1,960 / p <1e-300	114.7 EB05 74.8 · IC025 +3.9 3/3 methods agree	Not in label — unassessed	serious n=16	not reported in cached trials
Echolalia	19	81.5 51.3–129.6ROR 81.6 · χ² 1,345 / p 9e-295	71.4 EB05 48.3 · IC025 +3.9 3/3 methods agree	Not in label — unassessed	serious n=19	not reported in cached trials
Chronic kidney disease-mineral and bone disorder	44	55.1 40.7–74.4ROR 55.2 · χ² 2,187 / p <1e-300	51.7 EB05 40.1 · IC025 +4.6 3/3 methods agree	Not in label — unassessed	serious n=44	not reported in cached trials
Salivary gland calculus	14	51.3 30.0–87.4ROR 51.3 · χ² 616 / p 3e-136	46.4 EB05 29.4 · IC025 +3.3 3/3 methods agree	Not in label — unassessed	serious n=14	not reported in cached trials
Hyperparathyroidism secondary	96	50.9 41.5–62.4ROR 51.2 · χ² 4,468 / p <1e-300	48.5 EB05 40.9 · IC025 +5.0 3/3 methods agree	Not in label — unassessed	serious n=96	not reported in cached trials
Nephrogenic anaemia	171	49.0 42.1–57.1ROR 49.5 · χ² 7,703 / p <1e-300	47.0 EB05 41.4 · IC025 +5.1 3/3 methods agree	Not in label — unassessed	serious n=171	not reported in cached trials
Rebound acid hypersecretion	93	40.4 32.9–49.6ROR 40.6 · χ² 3,424 / p <1e-300	38.9 EB05 32.7 · IC025 +4.7 3/3 methods agree	Not in label — unassessed	serious n=93	not reported in cached trials
Vertigo positional	28	21.0 14.5–30.5ROR 21.1 · χ² 506 / p 3e-112	20.4 EB05 14.8 · IC025 +3.3 3/3 methods agree	Likely indication confounding shares a disease stem with the indications wording	serious n=24	not reported in cached trials
Inner ear disorder	14	17.2 10.2–29.1ROR 17.2 · χ² 195 / p 1e-44	16.2 EB05 9.6 · IC025 +2.5 3/3 methods agree	Not in label — unassessed	–	not reported in cached trials
Cerumen impaction	12	17.0 9.6–30.1ROR 17.0 · χ² 163 / p 1e-37	15.7 EB05 8.7 · IC025 +2.4 3/3 methods agree	Not in label — unassessed	serious n=12	not reported in cached trials
End stage renal disease	233	16.5 14.5–18.8ROR 16.8 · χ² 3,346 / p <1e-300	16.3 EB05 14.6 · IC025 +3.8 3/3 methods agree	Not in label — unassessed	serious PRR 15.0	not reported in cached trials
Sialoadenitis	17	16.4 10.1–26.4ROR 16.4 · χ² 227 / p 1e-51	15.5 EB05 9.8 · IC025 +2.7 3/3 methods agree	Not in label — unassessed	serious n=16	not reported in cached trials
Sick sinus syndrome	14	15.7 9.3–26.6ROR 15.7 · χ² 176 / p 2e-40	14.6 EB05 8.5 · IC025 +2.5 3/3 methods agree	Not in label — unassessed	serious n=14	not reported in cached trials
Aortic dilatation	12	14.4 8.1–25.4ROR 14.4 · χ² 135 / p 2e-31	12.8 EB05 6.9 · IC025 +2.2 3/3 methods agree	Not in label — unassessed	serious n=12	not reported in cached trials
Chronic kidney disease	841	14.3 13.4–15.3ROR 15.1 · χ² 10,331 / p <1e-300	14.2 EB05 13.4 · IC025 +3.7 3/3 methods agree	Not in label — unassessed	serious PRR 13.2	not reported in cached trials
Infusion site discharge	18	13.7 8.6–21.8ROR 13.7 · χ² 198 / p 3e-45	12.8 EB05 8.0 · IC025 +2.6 3/3 methods agree	Not in label — unassessed	serious n=13	not reported in cached trials
Vertigo (spinning dizziness)	630	13.5 12.5–14.6ROR 14.0 · χ² 7,210 / p <1e-300	13.3 EB05 12.5 · IC025 +3.6 3/3 methods agree	Likely indication confounding term in indications	serious PRR 11.2	not reported in cached trials
Cataplexy	13	11.9 6.9–20.5ROR 11.9 · χ² 117 / p 1e-27	10.2 EB05 5.8 · IC025 +2.1 3/3 methods agree	Not in label — unassessed	serious n=12	not reported in cached trials
Colonic polyp	15	11.7 7.0–19.4ROR 11.7 · χ² 134 / p 2e-31	10.3 EB05 6.1 · IC025 +2.2 3/3 methods agree	Not in label — unassessed	serious n=15	not reported in cached trials
Echocardiogram abnormal	12	11.2 6.3–19.8ROR 11.2 · χ² 101 / p 6e-24	9.4 EB05 5.2 · IC025 +2.0 3/3 methods agree	Lab value / disease marker	serious n=12	not reported in cached trials
Essential hypertension	22	11.1 7.3–16.8ROR 11.1 · χ² 190 / p 2e-43	10.1 EB05 6.7 · IC025 +2.5 3/3 methods agree	Not in label — unassessed	serious n=18	not reported in cached trials
Excoriation	21	10.6 6.9–16.3ROR 10.6 · χ² 172 / p 1e-39	9.6 EB05 6.3 · IC025 +2.4 3/3 methods agree	Not in label — unassessed	serious n=20	not reported in cached trials
Neck injury	24	10.6 7.1–15.8ROR 10.6 · χ² 198 / p 4e-45	9.7 EB05 6.6 · IC025 +2.5 3/3 methods agree	Not in label — unassessed	serious n=22	not reported in cached trials
Economic problem	125	10.6 8.9–12.6ROR 10.6 · χ² 1,064 / p 1e-233	10.3 EB05 8.9 · IC025 +3.0 3/3 methods agree	Reporting / coding artifact	serious PRR 10.4 · 71% consumer	not reported in cached trials
Infusion site pruritus	24	10.0 6.7–15.0ROR 10.0 · χ² 184 / p 3e-42	9.1 EB05 6.2 · IC025 +2.4 3/3 methods agree	Not in label — unassessed	serious n=17 · ♀ 100% (drug 74%) · 79% consumer	not reported in cached trials
Acute sinusitis	13	9.8 5.7–16.9ROR 9.8 · χ² 94 / p 2e-22	8.2 EB05 4.8 · IC025 +1.9 3/3 methods agree	Not in label — unassessed	serious n=12	not reported in cached trials
Costochondritis	12	9.6 5.4–16.9ROR 9.6 · χ² 83 / p 4e-20	7.8 EB05 4.5 · IC025 +1.8 3/3 methods agree	Not in label — unassessed	serious n=11	not reported in cached trials
Bronchitis chronic	18	9.5 6.0–15.1ROR 9.5 · χ² 128 / p 6e-30	8.3 EB05 5.3 · IC025 +2.2 3/3 methods agree	Not in label — unassessed	serious n=17	not reported in cached trials
Middle ear effusion	16	9.5 5.8–15.5ROR 9.5 · χ² 112 / p 2e-26	8.1 EB05 5.0 · IC025 +2.1 3/3 methods agree	Not in label — unassessed	serious n=12	not reported in cached trials
Ear disorder	33	9.3 6.6–13.1ROR 9.3 · χ² 235 / p 2e-53	8.6 EB05 6.3 · IC025 +2.5 3/3 methods agree	Not in label — unassessed	serious n=28	not reported in cached trials
Pre-existing condition improved	45	9.3 6.9–12.4ROR 9.3 · χ² 322 / p 3e-72	8.7 EB05 6.7 · IC025 +2.6 3/3 methods agree	Not in label — unassessed	serious n=30	not reported in cached trials
Infusion site haemorrhage	23	9.2 6.1–13.9ROR 9.2 · χ² 159 / p 8e-37	8.3 EB05 5.6 · IC025 +2.3 3/3 methods agree	Not in label — unassessed	serious n=13 · ♀ 100% (drug 74%) · 100% consumer	not reported in cached trials
Diabetic neuropathy	35	9.1 6.6–12.7ROR 9.2 · χ² 244 / p 3e-55	8.5 EB05 6.3 · IC025 +2.5 3/3 methods agree	Not in label — unassessed	serious n=35	not reported in cached trials
Femoral neck fracture	36	9.1 6.6–12.7ROR 9.1 · χ² 250 / p 1e-56	8.5 EB05 6.3 · IC025 +2.5 3/3 methods agree	Not in label — unassessed	serious n=36 · 100% clinician	not reported in cached trials
Rhinitis allergic	31	9.1 6.4–12.9ROR 9.1 · χ² 213 / p 1e-48	8.3 EB05 6.0 · IC025 +2.4 3/3 methods agree	Not in label — unassessed	serious n=28	not reported in cached trials
Hypertensive heart disease	13	9.0 5.2–15.5ROR 9.0 · χ² 84 / p 3e-20	7.4 EB05 4.4 · IC025 +1.8 3/3 methods agree	Not in label — unassessed	serious n=13	not reported in cached trials
Narcolepsy	13	9.0 5.2–15.5ROR 9.0 · χ² 84 / p 3e-20	7.4 EB05 4.4 · IC025 +1.8 3/3 methods agree	Not in label — unassessed	serious n=12	not reported in cached trials
Lumbar spinal stenosis	20	8.9 5.7–13.8ROR 8.9 · χ² 131 / p 1e-30	7.8 EB05 5.2 · IC025 +2.1 3/3 methods agree	Not in label — unassessed	serious n=19	not reported in cached trials
Intervertebral disc degeneration	63	8.8 6.9–11.3ROR 8.8 · χ² 425 / p 1e-94	8.4 EB05 6.8 · IC025 +2.6 3/3 methods agree	Not in label — unassessed	serious PRR 8.3	not reported in cached trials
Labyrinthitis	17	8.7 5.4–14.0ROR 8.7 · χ² 107 / p 2e-25	7.4 EB05 4.7 · IC025 +2.0 3/3 methods agree	Not in label — unassessed	serious n=14	not reported in cached trials

Trial evidence (ClinicalTrials.gov)

✓ Trial adverse-event data found on ClinicalTrials.gov

Largest completed trials with posted results that list Meclizine as a study intervention. The right-hand column of the signal table shows whether each FAERS term was also recorded in these trials, with a real denominator (0 of 40 signal terms matched).

NCT01443858 — Meclizine as a Potential Smoking Cessation Treatment (N=146, PHASE2; 16 AE terms posted; arms: Control; 25mg Meclizine; 50mg Meclizine)

Caveats: trial populations, doses and follow-up differ from the reporting population; AE terms are sponsor-coded and matched here by wording; absence from a trial list means the term was not reported above the sponsor's frequency threshold, not that it cannot occur.

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
Dizziness	1,633	4.2 4.1–4.4ROR 4.6 · χ² 4,138 / p <1e-300	4.2 EB05 4.1 · IC025 +2.0 3/3 methods agree	Not in label — unassessed	serious PRR 4.2	not reported in cached trials
Nausea	1,420	2.3 2.2–2.4ROR 2.5 · χ² 1,114 / p 1e-244	2.3 EB05 2.2 · IC025 +1.1 3/3 methods agree	Not in label — unassessed	serious PRR 2.6	NCT01443858: 2/25 (8.0%) on Meclizine; 6/19 (31.6%) control
Fatigue (tiredness)	1,370	2.3 2.2–2.4ROR 2.4 · χ² 1,020 / p 4e-224	2.3 EB05 2.2 · IC025 +1.1 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 2.4	NCT01443858: 5/25 (20.0%) on Meclizine; 2/19 (10.5%) control
Headache	1,060	2.2 2.1–2.3ROR 2.3 · χ² 704 / p 3e-155	2.2 EB05 2.1 · IC025 +1.0 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 2.4	NCT01443858: 2/25 (8.0%) on Meclizine; 3/19 (15.8%) control
Diarrhoea (diarrhea)	1,047	2.1 2.0–2.2ROR 2.2 · χ² 624 / p 4e-138	2.1 EB05 2.0 · IC025 +1.0	Not in label — unassessed	serious PRR 2.1	NCT01443858: 1/25 (4.0%) on Meclizine; 2/19 (10.5%) control
Pain	1,008	2.1 2.0–2.2ROR 2.2 · χ² 611 / p 3e-135	2.1 EB05 2.0 · IC025 +1.0 3/3 methods agree	Not in label — unassessed	serious PRR 2.3	not reported in cached trials
Fall	998	3.9 3.7–4.1ROR 4.1 · χ² 2,165 / p <1e-300	3.9 EB05 3.7 · IC025 +1.8 3/3 methods agree	Not in label — unassessed	serious PRR 3.6	not reported in cached trials
Dyspnoea (shortness of breath)	878	2.0 1.9–2.1ROR 2.1 · χ² 454 / p 4e-101	2.0 EB05 1.9 · IC025 +0.9	Not in label — unassessed	serious PRR 1.9	not reported in cached trials
Chronic kidney disease	841	14.3 13.4–15.3ROR 15.1 · χ² 10,331 / p <1e-300	14.2 EB05 13.4 · IC025 +3.7 3/3 methods agree	Not in label — unassessed	serious PRR 13.2	not reported in cached trials
Asthenia (weakness)	819	2.8 2.6–3.0ROR 2.9 · χ² 974 / p 4e-214	2.8 EB05 2.7 · IC025 +1.4 3/3 methods agree	Not in label — unassessed	serious PRR 2.8	not reported in cached trials
Drug ineffective (drug did not work)	769	0.8 0.7–0.8ROR 0.7 · χ² 65 / p 3e-16	0.8 EB05 0.7 · IC025 -0.5 PRR-only: not supported by EBGM or IC	Reporting / coding artifact	serious PRR 0.8	not reported in cached trials
Vomiting	729	2.0 1.9–2.2ROR 2.1 · χ² 377 / p 3e-84	2.0 EB05 1.9 · IC025 +0.9	Labeled adverse reaction exact term	serious PRR 1.9	not reported in cached trials
Off label use (used outside approved label)	640	1.0 0.9–1.0ROR 1.0 · χ² 2 / p 0.109	1.0 EB05 0.9 · IC025 -0.2 PRR-only: not supported by EBGM or IC	Reporting / coding artifact	serious PRR 0.9	not reported in cached trials
Renal failure (kidney failure)	640	6.2 5.8–6.7ROR 6.4 · χ² 2,794 / p <1e-300	6.2 EB05 5.8 · IC025 +2.5 3/3 methods agree	Not in label — unassessed	serious PRR 5.7	not reported in cached trials
Vertigo (spinning dizziness)	630	13.5 12.5–14.6ROR 14.0 · χ² 7,210 / p <1e-300	13.3 EB05 12.5 · IC025 +3.6 3/3 methods agree	Likely indication confounding term in indications	serious PRR 11.2	not reported in cached trials

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-mineral and bone disorder — n=44, PRR 55.1
Hyperparathyroidism secondary — n=96, PRR 50.9
Nephrogenic anaemia — n=171, PRR 49.0
Rebound acid hypersecretion — n=93, PRR 40.4
End stage renal disease — n=233, PRR 16.5
Chronic kidney disease — n=841, PRR 14.3
Essential hypertension — n=22, PRR 11.1
Excoriation — n=21, PRR 10.6
Neck injury — n=24, PRR 10.6
Infusion site pruritus — n=24, PRR 10.0

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 dizziness, nausea, fatigue, headache, diarrhoea, pain. 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, field patient.drug.openfda.generic_name.exact, 1,151 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
ClinicalTrials.gov API v2 (query MECLIZINE, results-bearing studies sorted by enrollment)

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.