Drug · FAERS side-effect profile with label screen

Fosamprenavir side effects: what 130 FDA adverse event reports show

Fosamprenavir Calcium · 5 reaction terms · 70 drug–reaction co-reports · data 2026-09-14

Drug class

Not stated in label

Label matched

Fosamprenavir Calcium (Fosamprenavir Calcium)

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

Who reports

130 reports · 95% serious · 10 with death outcome · 31% female

openFDA FAERS counts, all years, deduplication not applied

Used for

Fosamprenavir calcium tablets are indicated in combination with other antiretroviral agents for the treatment of human immunodeficiency virus (HIV-1) infection. The following points should be considered when initiating therapy with fosamprenavir calciu.

FDA label, Indications and Usage

What it is

Fosamprenavir calcium, USP is a prodrug of amprenavir, an inhibitor of HIV protease.

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 4 strongest signals

Reporting / coding artifact 1Lab value / disease marker 1Not in label — unassessed 2

What the badges mean

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 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
Blood bilirubin increased	25	149.0 104.7–212.0ROR 184.3 · χ² 3,530 / p <1e-300	133.9 EB05 95.4 · IC025 +4.6 3/3 methods agree	Lab value / disease marker	serious PRR 103.2 · 100% clinician	no trial data cached
Haematuria (blood in urine)	26	122.4 86.7–172.6ROR 152.7 · χ² 3,012 / p <1e-300	112.4 EB05 80.6 · IC025 +4.6 3/3 methods agree	Not in label — unassessed	serious PRR 81.4 · 100% clinician	no trial data cached
Pregnancy	7	55.8 27.2–114.8ROR 59.0 · χ² 324 / p 8e-73	48.8 EB05 25.4 · IC025 +2.3 3/3 methods agree	Not in label — unassessed	serious PRR 49.3	no trial data cached
Drug exposure during pregnancy	8	37.4 19.1–73.2ROR 39.8 · χ² 249 / p 3e-56	34.5 EB05 18.6 · IC025 +2.4 3/3 methods agree	Reporting / coding artifact	serious PRR 25.1	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
Haematuria (blood in urine)	26	122.4 86.7–172.6ROR 152.7 · χ² 3,012 / p <1e-300	112.4 EB05 80.6 · IC025 +4.6 3/3 methods agree	Not in label — unassessed	serious PRR 81.4 · 100% clinician	no trial data cached
Blood bilirubin increased	25	149.0 104.7–212.0ROR 184.3 · χ² 3,530 / p <1e-300	133.9 EB05 95.4 · IC025 +4.6 3/3 methods agree	Lab value / disease marker	serious PRR 103.2 · 100% clinician	no trial data cached
Drug exposure during pregnancy	8	37.4 19.1–73.2ROR 39.8 · χ² 249 / p 3e-56	34.5 EB05 18.6 · IC025 +2.4 3/3 methods agree	Reporting / coding artifact	serious PRR 25.1	no trial data cached
Pregnancy	7	55.8 27.2–114.8ROR 59.0 · χ² 324 / p 8e-73	48.8 EB05 25.4 · IC025 +2.3 3/3 methods agree	Not in label — unassessed	serious PRR 49.3	no trial data cached
Abortion induced	4	68.5 26.1–179.7ROR 70.6 · χ² 203 / p 3e-46	51.7 EB05 21.0 · IC025 +1.2 3/3 methods agree	Not in label — unassessed	serious PRR 43.1	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.

Haematuria — n=26, PRR 122.4

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 Fosamprenavir?

In FDA FAERS, the most frequently co-reported reaction terms for Fosamprenavir are haematuria, blood bilirubin increased, pregnancy, abortion induced. 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 Fosamprenavir have an FDA boxed warning?

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

Do FAERS signals prove that Fosamprenavir 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 5cd1eead-9fc1-426c-bee8-214ffa7d9dc1, effective 20260630; matched on openfda.generic_name.exact:"FOSAMPRENAVIR CALCIUM")
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, 5 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.