Methazolamide side effects: what 339 FDA adverse event reports show

Methazolamide · 8 reaction terms · 93 drug–reaction co-reports · data 2026-09-14

Drug class

Not stated in label

Who reports

339 reports · 63% serious · 28 with death outcome · 56% female

openFDA FAERS counts, all years, deduplication not applied

Used for

Methazolamide tablets are indicated in the treatment of ocular conditions where lowering intraocular pressure is likely to be of therapeutic benefit, such as chronic open-angle glaucoma, secondary glaucoma, and preoperatively in acute angle-closure glaucoma where lowering the intraocular pressure is desired before surgery.

FDA label, Indications and Usage

What it is

DESCRIPTION Methazolamide USP, a sulfonamide derivative, is a white or faintly yellow, crystalline powder having a slight odor, soluble in dimethylformamide, slightly soluble in acetone, very slightly soluble in water and in alcohol.

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 7 strongest signals

Likely indication confounding 2Lab value / disease marker 1Not in label — unassessed 4

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.
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 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
Intraocular pressure increased (raised eye pressure)	14	67.5 40.4–112.8ROR 70.4 · χ² 852 / p 2e-187	62.0 EB05 39.3 · IC025 +3.5 3/3 methods agree	Likely indication confounding term in indications; also in warnings	serious PRR 72.2	no trial data cached
Middle insomnia	15	49.9 30.4–81.9ROR 52.2 · χ² 671 / p 3e-148	47.1 EB05 30.3 · IC025 +3.4 3/3 methods agree	Not in label — unassessed	serious PRR 100.1	no trial data cached
Sensory disturbance	13	49.9 29.3–85.1ROR 51.8 · χ² 575 / p 2e-127	46.7 EB05 29.0 · IC025 +3.2 3/3 methods agree	Not in label — unassessed	serious PRR 70.9	no trial data cached
Hernia	13	41.8 24.5–71.3ROR 43.4 · χ² 478 / p 3e-106	39.6 EB05 24.6 · IC025 +3.1 3/3 methods agree	Not in label — unassessed	serious PRR 43.2	no trial data cached
Heart rate irregular	14	38.1 22.8–63.7ROR 39.7 · χ² 470 / p 2e-104	36.4 EB05 23.0 · IC025 +3.2 3/3 methods agree	Not in label — unassessed	serious PRR 46.1	no trial data cached
Glaucoma	8	25.7 13.0–51.0ROR 26.3 · χ² 166 / p 3e-38	23.9 EB05 12.2 · IC025 +2.2 3/3 methods agree	Likely indication confounding term in indications; also in warnings	serious PRR 25.5	no trial data cached
Bone density decreased	13	25.4 14.9–43.3ROR 26.4 · χ² 281 / p 2e-63	24.5 EB05 15.1 · IC025 +2.8 3/3 methods agree	Lab value / disease marker	serious PRR 29.2	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
Middle insomnia	15	49.9 30.4–81.9ROR 52.2 · χ² 671 / p 3e-148	47.1 EB05 30.3 · IC025 +3.4 3/3 methods agree	Not in label — unassessed	serious PRR 100.1	no trial data cached
Heart rate irregular	14	38.1 22.8–63.7ROR 39.7 · χ² 470 / p 2e-104	36.4 EB05 23.0 · IC025 +3.2 3/3 methods agree	Not in label — unassessed	serious PRR 46.1	no trial data cached
Intraocular pressure increased (raised eye pressure)	14	67.5 40.4–112.8ROR 70.4 · χ² 852 / p 2e-187	62.0 EB05 39.3 · IC025 +3.5 3/3 methods agree	Likely indication confounding term in indications; also in warnings	serious PRR 72.2	no trial data cached
Bone density decreased	13	25.4 14.9–43.3ROR 26.4 · χ² 281 / p 2e-63	24.5 EB05 15.1 · IC025 +2.8 3/3 methods agree	Lab value / disease marker	serious PRR 29.2	no trial data cached
Hernia	13	41.8 24.5–71.3ROR 43.4 · χ² 478 / p 3e-106	39.6 EB05 24.6 · IC025 +3.1 3/3 methods agree	Not in label — unassessed	serious PRR 43.2	no trial data cached
Sensory disturbance	13	49.9 29.3–85.1ROR 51.8 · χ² 575 / p 2e-127	46.7 EB05 29.0 · IC025 +3.2 3/3 methods agree	Not in label — unassessed	serious PRR 70.9	no trial data cached
Glaucoma	8	25.7 13.0–51.0ROR 26.3 · χ² 166 / p 3e-38	23.9 EB05 12.2 · IC025 +2.2 3/3 methods agree	Likely indication confounding term in indications; also in warnings	serious PRR 25.5	no trial data cached
Rebound effect	3	16.4 5.3–50.5ROR 16.5 · χ² 29 / p 3e-8	8.7 EB05 2.3 · IC025 +0.3 3/3 methods agree	Not in label — unassessed	serious PRR 24.2	no trial data cached

Unlabeled candidate signals

Every screened signal with n ≥ 20 was either labeled, an indication term, or an artifact pattern — no unlabeled candidate stood out in the top signals.

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 Methazolamide?

In FDA FAERS, the most frequently co-reported reaction terms for Methazolamide are middle insomnia, heart rate irregular, intraocular pressure increased, bone density decreased, hernia, sensory 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 Methazolamide have an FDA boxed warning?

No. The FDA label retrieved for Methazolamide has no boxed warning; see the label's Warnings and Precautions for the recognised risks.

Do FAERS signals prove that Methazolamide 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 0c0ba5c7-c53e-4e29-a7ff-48fddc5a9258, effective 20251023; matched on openfda.generic_name.exact:"METHAZOLAMIDE")
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, 8 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.