Drug · FAERS side-effect profile with label screen

Monobasic side effects: what 421 FDA adverse event reports show

Potassium Phosphate, Monobasic · 13 reaction terms · 201 drug–reaction co-reports · data 2026-09-14

Drug class

Not stated in label

Label matched

Potassium Phosphate, Monobasic (K Phos Original)

closest FDA label found for this product string; brand list suppressed because the label is a related product, not an exact match

Who reports

421 reports · 86% serious · 106 with death outcome · 39% female

openFDA FAERS counts, all years, deduplication not applied

Used for

INDICATONS AND USAGE For use in patients with elevated urinary pH. K-PHOS® ORIGINAL helps keep calcium soluble and reduces odor and rash caused by ammoniacal urine. Also, by acidifying the urine, it increases the antibacterial activity of methenamine mandelate and methenamine hippurate.

FDA label, Indications and Usage

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 12 strongest signals

No label text to screen 12

What the badges mean

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.
No label text to screen No validated FDA label was retrievable for this product, so the screen could not run. Disproportionality only.

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
Toxic epidermal necrolysis (severe skin peeling reaction)	30	99.3 70.3–140.2ROR 106.8 · χ² 2,817 / p <1e-300	93.3 EB05 68.5 · IC025 +4.6 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious PRR 66.6 · 97% clinician	no trial data cached
Macular degeneration	16	67.0 41.4–108.3ROR 69.6 · χ² 974 / p 4e-214	62.1 EB05 40.6 · IC025 +3.6 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious PRR 48.4	no trial data cached
Vaginal discharge	8	39.7 20.0–78.9ROR 40.4 · χ² 264 / p 1e-59	36.4 EB05 19.7 · IC025 +2.4 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=8	no trial data cached
Cytomegalovirus infection	11	33.0 18.4–59.1ROR 33.8 · χ² 310 / p 1e-69	31.3 EB05 18.6 · IC025 +2.8 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious PRR 22.4	no trial data cached
Respiratory failure	48	32.8 25.1–42.8ROR 36.9 · χ² 1,451 / p <1e-300	32.4 EB05 25.4 · IC025 +4.1 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious PRR 22.0 · ♀ 5% (drug 39%)	no trial data cached
Paraesthesia oral	8	27.7 14.0–55.1ROR 28.3 · χ² 180 / p 2e-41	25.8 EB05 13.5 · IC025 +2.2 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious PRR 33.2	no trial data cached
Febrile neutropenia	36	27.1 19.8–37.0ROR 29.5 · χ² 881 / p 7e-194	26.7 EB05 20.2 · IC025 +3.8 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious PRR 18.2 · ♀ 9% (drug 39%) · 97% clinician	no trial data cached
Cytokine release syndrome	10	26.2 14.2–48.3ROR 26.8 · χ² 217 / p 2e-49	24.9 EB05 14.1 · IC025 +2.5 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious PRR 17.7	no trial data cached
Metastases to lung	6	25.9 11.7–57.3ROR 26.3 · χ² 120 / p 3e-28	23.0 EB05 9.5 · IC025 +1.7 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious PRR 17.5	no trial data cached
Drug reaction with eosinophilia and systemic symptoms	10	19.5 10.6–36.0ROR 19.9 · χ² 158 / p 2e-36	18.2 EB05 9.6 · IC025 +2.3 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious PRR 13.1	no trial data cached
Procedural pain	9	16.2 8.5–30.9ROR 16.5 · χ² 114 / p 7e-27	14.4 EB05 6.8 · IC025 +2.0 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious PRR 18.7	no trial data cached
Bone marrow failure	6	14.6 6.6–32.3ROR 14.8 · χ² 63 / p 1e-15	11.0 EB05 4.2 · IC025 +1.4 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious PRR 9.9	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
Respiratory failure	48	32.8 25.1–42.8ROR 36.9 · χ² 1,451 / p <1e-300	32.4 EB05 25.4 · IC025 +4.1 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious PRR 22.0 · ♀ 5% (drug 39%)	no trial data cached
Febrile neutropenia	36	27.1 19.8–37.0ROR 29.5 · χ² 881 / p 7e-194	26.7 EB05 20.2 · IC025 +3.8 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious PRR 18.2 · ♀ 9% (drug 39%) · 97% clinician	no trial data cached
Toxic epidermal necrolysis (severe skin peeling reaction)	30	99.3 70.3–140.2ROR 106.8 · χ² 2,817 / p <1e-300	93.3 EB05 68.5 · IC025 +4.6 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious PRR 66.6 · 97% clinician	no trial data cached
Macular degeneration	16	67.0 41.4–108.3ROR 69.6 · χ² 974 / p 4e-214	62.1 EB05 40.6 · IC025 +3.6 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious PRR 48.4	no trial data cached
Cytomegalovirus infection	11	33.0 18.4–59.1ROR 33.8 · χ² 310 / p 1e-69	31.3 EB05 18.6 · IC025 +2.8 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious PRR 22.4	no trial data cached
Drug reaction with eosinophilia and systemic symptoms	10	19.5 10.6–36.0ROR 19.9 · χ² 158 / p 2e-36	18.2 EB05 9.6 · IC025 +2.3 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious PRR 13.1	no trial data cached
Cytokine release syndrome	10	26.2 14.2–48.3ROR 26.8 · χ² 217 / p 2e-49	24.9 EB05 14.1 · IC025 +2.5 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious PRR 17.7	no trial data cached
Procedural pain	9	16.2 8.5–30.9ROR 16.5 · χ² 114 / p 7e-27	14.4 EB05 6.8 · IC025 +2.0 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious PRR 18.7	no trial data cached
Paraesthesia oral	8	27.7 14.0–55.1ROR 28.3 · χ² 180 / p 2e-41	25.8 EB05 13.5 · IC025 +2.2 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious PRR 33.2	no trial data cached
Vaginal discharge	8	39.7 20.0–78.9ROR 40.4 · χ² 264 / p 1e-59	36.4 EB05 19.7 · IC025 +2.4 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious n=8	no trial data cached
Bone marrow failure	6	14.6 6.6–32.3ROR 14.8 · χ² 63 / p 1e-15	11.0 EB05 4.2 · IC025 +1.4 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious PRR 9.9	no trial data cached
Metastases to lung	6	25.9 11.7–57.3ROR 26.3 · χ² 120 / p 3e-28	23.0 EB05 9.5 · IC025 +1.7 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious PRR 17.5	no trial data cached
Pneumocystis jirovecii pneumonia	3	15.0 4.8–46.2ROR 15.1 · χ² 26 / p 1e-7	7.8 EB05 2.2 · IC025 +0.3 3/3 methods agree	No label text to screen label has no adverse-reaction text	serious PRR 10.1	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 Monobasic?

In FDA FAERS, the most frequently co-reported reaction terms for Monobasic are respiratory failure, febrile neutropenia, toxic epidermal necrolysis, macular degeneration, cytomegalovirus infection, drug reaction with eosinophilia and systemic symptoms. 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 Monobasic have an FDA boxed warning?

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

Do FAERS signals prove that Monobasic 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 04557ab3-6d21-49b4-b849-744c75b8a630, effective 20230223; matched on openfda.generic_name.exact:"POTASSIUM PHOSPHATE, MONOBASIC")
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, 13 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.