Abacavir side effects: what 5,947 FDA adverse event reports show
Drug class
Not stated in label
Who reports
5,947 reports · 95% serious · 750 with death outcome · 39% female
Used for
Abacavir tablet, a nucleoside analogue human immunodeficiency virus (HIV-1) reverse transcriptase inhibitor, is indicated in combination with other antiretroviral agents for the treatment of HIV-1 infection. Abacavir tablets USP 300 mg, in combination with other antiretroviral agents, are indicated for the treatment of human immunodeficiency virus (HIV-1) infection.
What it is
Abacavir sulfate is a synthetic carbocyclic nucleoside analogue with inhibitory activity against HIV-1.
Boxed warning
HYPERSENSITIVITY REACTIONS WARNING: HYPERSENSITIVITY REACTIONS See full prescribing information for complete boxed warning. Serious and sometimes fatal hypersensitivity reactions have occurred with abacavir sulfate. ( 5.1 ) Hypersensitivity to abacavir is a multi-organ clinical syndrome.
Causality screen of the 40 strongest signals
What the badges mean
- Labeled — boxed warning The term (or its clinical synonym) appears in the FDA boxed warning: causality is regulator-recognised and considered serious.
- Labeled adverse reaction The exact term appears in the label's warnings or adverse-reactions sections: a known, expected effect. The FAERS signal confirms the label rather than discovering anything.
- Labeled (related wording) The label describes this effect under different wording (e.g. 'neutropenia' for 'neutrophil count decreased'). Treated as known.
- 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. 264 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 |
|---|---|---|---|---|---|---|
| Schizophrenia | 165 | 48.5 41.7–56.4ROR 49.8 · χ² 7,525 / p <1e-300 | 47.6 EB05 41.8 · IC025 +5.1 3/3 methods agree | Not in label — unassessed | serious PRR 30.0 · ♀ 96% (drug 39%) · 98% clinician | no trial data cached |
| Drug resistance | 292 | 40.5 36.2–45.4ROR 42.6 · χ² 11,105 / p <1e-300 | 40.0 EB05 36.3 · IC025 +5.0 3/3 methods agree | Reporting / coding artifact | serious PRR 26.8 · 91% clinician | no trial data cached |
| Coeliac disease | 105 | 38.1 31.5–46.1ROR 38.8 · χ² 3,719 / p <1e-300 | 37.5 EB05 31.8 · IC025 +4.7 3/3 methods agree | Not in label — unassessed | serious PRR 28.4 · ♀ 100% (drug 39%) · 94% clinician | no trial data cached |
| Immunodeficiency | 137 | 33.1 28.0–39.1ROR 33.9 · χ² 4,195 / p <1e-300 | 32.7 EB05 28.3 · IC025 +4.6 3/3 methods agree | Likely indication confounding term in indications | serious PRR 21.6 · ♀ 86% (drug 39%) · 94% clinician | no trial data cached |
| Bursitis | 105 | 30.9 25.6–37.4ROR 31.5 · χ² 2,988 / p <1e-300 | 30.5 EB05 25.9 · IC025 +4.4 3/3 methods agree | Not in label — unassessed | serious PRR 21.9 · ♀ 100% (drug 39%) · 94% clinician | no trial data cached |
| Eyelid ptosis | 75 | 26.2 20.9–32.8ROR 26.5 · χ² 1,779 / p <1e-300 | 25.8 EB05 21.3 · IC025 +4.1 3/3 methods agree | Not in label — unassessed | serious n=75 · ♀ 3% (drug 39%) · 94% clinician | no trial data cached |
| Hepatotoxicity (liver damage) | 138 | 22.1 18.7–26.1ROR 22.6 · χ² 2,742 / p <1e-300 | 21.9 EB05 19.0 · IC025 +4.1 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 13.6 · ♀ 91% (drug 39%) · 97% clinician | no trial data cached |
| Prescribed overdose | 120 | 22.0 18.4–26.3ROR 22.4 · χ² 2,371 / p <1e-300 | 21.8 EB05 18.7 · IC025 +4.0 3/3 methods agree | Not in label — unassessed | serious PRR 22.6 · ♀ 100% (drug 39%) · 95% clinician | no trial data cached |
| Nephropathy toxic | 61 | 19.4 15.1–24.9ROR 19.6 · χ² 1,042 / p 8e-229 | 19.2 EB05 15.5 · IC025 +3.6 3/3 methods agree | Not in label — unassessed | serious PRR 12.0 · 93% clinician | no trial data cached |
| Blood bilirubin increased | 143 | 18.7 15.9–22.0ROR 19.1 · χ² 2,370 / p <1e-300 | 18.6 EB05 16.2 · IC025 +3.9 3/3 methods agree | Lab value / disease marker | serious PRR 12.8 · ♀ 81% (drug 39%) · 93% clinician | no trial data cached |
| Cholelithiasis | 173 | 18.7 16.1–21.7ROR 19.2 · χ² 2,868 / p <1e-300 | 18.6 EB05 16.4 · IC025 +3.9 3/3 methods agree | Not in label — unassessed | serious PRR 11.9 · ♀ 92% (drug 39%) · 98% clinician | no trial data cached |
| Exposure during pregnancy | 299 | 17.0 15.2–19.0ROR 17.9 · χ² 4,487 / p <1e-300 | 16.9 EB05 15.4 · IC025 +3.9 3/3 methods agree | Reporting / coding artifact | serious PRR 14.2 · ♀ 100% (drug 39%) · 95% clinician | no trial data cached |
| Treatment failure | 352 | 15.2 13.7–16.8ROR 16.1 · χ² 4,647 / p <1e-300 | 15.1 EB05 13.8 · IC025 +3.7 3/3 methods agree | Reporting / coding artifact | serious PRR 17.6 · ♀ 74% (drug 39%) · 97% clinician | no trial data cached |
| Anhedonia | 113 | 15.1 12.6–18.1ROR 15.4 · χ² 1,469 / p <1e-300 | 15.0 EB05 12.8 · IC025 +3.5 3/3 methods agree | Not in label — unassessed | serious PRR 10.0 · ♀ 16% (drug 39%) · 81% consumer | no trial data cached |
| Psychotic disorder | 126 | 15.1 12.7–18.0ROR 15.4 · χ² 1,640 / p <1e-300 | 15.0 EB05 12.9 · IC025 +3.5 3/3 methods agree | Not in label — unassessed | serious PRR 9.9 · ♀ 90% (drug 39%) · 91% clinician | no trial data cached |
| Upper respiratory tract infection (cold/sinus infection) | 196 | 15.0 13.1–17.3ROR 15.5 · χ² 2,548 / p <1e-300 | 14.9 EB05 13.3 · IC025 +3.6 3/3 methods agree | Labeled (related wording) related wording | serious PRR 15.4 · ♀ 98% (drug 39%) · 95% clinician | no trial data cached |
| Foetal exposure during pregnancy | 338 | 14.7 13.3–16.3ROR 15.6 · χ² 4,309 / p <1e-300 | 14.6 EB05 13.4 · IC025 +3.7 3/3 methods agree | Reporting / coding artifact | serious PRR 9.0 | no trial data cached |
| Rash erythematous | 192 | 14.5 12.6–16.7ROR 15.0 · χ² 2,396 / p <1e-300 | 14.4 EB05 12.8 · IC025 +3.6 3/3 methods agree | Not in label — unassessed | serious PRR 17.8 · ♀ 100% (drug 39%) · 96% clinician | no trial data cached |
| End stage renal disease | 75 | 14.4 11.5–18.1ROR 14.6 · χ² 920 / p 3e-202 | 14.3 EB05 11.7 · IC025 +3.3 3/3 methods agree | Not in label — unassessed | serious PRR 8.7 | no trial data cached |
| Treatment noncompliance | 216 | 14.1 12.3–16.0ROR 14.6 · χ² 2,606 / p <1e-300 | 14.0 EB05 12.5 · IC025 +3.5 3/3 methods agree | Reporting / coding artifact | serious PRR 12.4 · 97% clinician | no trial data cached |
| Renal tubular necrosis | 38 | 13.7 10.0–18.8ROR 13.8 · χ² 432 / p 3e-96 | 13.3 EB05 10.0 · IC025 +3.0 3/3 methods agree | Not in label — unassessed | serious PRR 8.3 · 91% clinician | no trial data cached |
| Hepatic enzyme increased | 257 | 13.4 11.9–15.1ROR 13.9 · χ² 2,930 / p <1e-300 | 13.3 EB05 12.0 · IC025 +3.5 3/3 methods agree | Labeled (related wording) related wording | serious PRR 11.6 · ♀ 91% (drug 39%) · 94% clinician | no trial data cached |
| Economic problem | 55 | 12.6 9.7–16.4ROR 12.7 · χ² 575 / p 2e-127 | 12.4 EB05 9.7 · IC025 +3.1 3/3 methods agree | Reporting / coding artifact | serious PRR 8.2 · ♀ 13% (drug 39%) | no trial data cached |
| Contraindicated product administered | 106 | 12.4 10.3–15.0ROR 12.6 · χ² 1,100 / p 1e-241 | 12.3 EB05 10.4 · IC025 +3.2 3/3 methods agree | Reporting / coding artifact | serious PRR 9.1 · ♀ 96% (drug 39%) · 94% clinician | no trial data cached |
| Hyperbilirubinaemia | 35 | 12.0 8.6–16.7ROR 12.1 · χ² 341 / p 2e-76 | 11.5 EB05 8.5 · IC025 +2.8 3/3 methods agree | Not in label — unassessed | serious PRR 7.2 | no trial data cached |
| Oral candidiasis (oral thrush) | 44 | 12.0 8.9–16.1ROR 12.0 · χ² 430 / p 9e-96 | 11.6 EB05 8.8 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious PRR 9.9 · ♀ 12% (drug 39%) | no trial data cached |
| Hepatitis c | 40 | 11.6 8.5–15.8ROR 11.7 · χ² 375 / p 7e-84 | 11.1 EB05 8.4 · IC025 +2.8 3/3 methods agree | Labeled (related wording) related wording | serious PRR 7.5 | no trial data cached |
| Proteinuria | 61 | 11.4 8.9–14.7ROR 11.5 · χ² 569 / p 4e-126 | 11.2 EB05 8.9 · IC025 +3.0 3/3 methods agree | Not in label — unassessed | serious PRR 7.7 · 91% clinician | no trial data cached |
| Acute hepatic failure | 43 | 11.2 8.3–15.1ROR 11.3 · χ² 388 / p 1e-86 | 10.8 EB05 8.2 · IC025 +2.8 3/3 methods agree | Labeled (related wording) related wording | serious PRR 6.8 · ♀ 18% (drug 39%) · 95% clinician | no trial data cached |
| Decreased immune responsiveness | 30 | 10.9 7.6–15.5ROR 10.9 · χ² 258 / p 2e-58 | 10.2 EB05 7.2 · IC025 +2.6 3/3 methods agree | Not in label — unassessed | serious PRR 8.2 · ♀ 100% (drug 39%) · 97% clinician | no trial data cached |
| Brain oedema | 38 | 10.6 7.7–14.6ROR 10.7 · χ² 322 / p 3e-72 | 10.1 EB05 7.5 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious PRR 6.5 · 92% clinician | no trial data cached |
| Hyperlipidaemia | 36 | 10.6 7.7–14.7ROR 10.7 · χ² 303 / p 3e-68 | 10.1 EB05 7.4 · IC025 +2.7 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 6.9 · ♀ 7% (drug 39%) · 93% clinician | no trial data cached |
| Hepatomegaly | 29 | 10.4 7.2–14.9ROR 10.4 · χ² 236 / p 1e-53 | 9.7 EB05 6.8 · IC025 +2.5 3/3 methods agree | Labeled — boxed warning exact term | serious PRR 6.8 | no trial data cached |
| Nephropathy | 26 | 9.8 6.7–14.4ROR 9.8 · χ² 196 / p 7e-45 | 9.0 EB05 6.2 · IC025 +2.4 3/3 methods agree | Not in label — unassessed | serious PRR 5.6 · ♀ 17% (drug 39%) | no trial data cached |
| Adrenal insufficiency | 32 | 9.4 6.7–13.4ROR 9.5 · χ² 233 / p 7e-53 | 8.8 EB05 6.4 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious PRR 5.6 | no trial data cached |
| Tuberculosis | 34 | 9.3 6.7–13.1ROR 9.4 · χ² 245 / p 2e-55 | 8.7 EB05 6.4 · IC025 +2.5 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 5.8 · 94% clinician | no trial data cached |
| Splenomegaly | 30 | 9.1 6.3–12.9ROR 9.1 · χ² 207 / p 4e-47 | 8.3 EB05 6.0 · IC025 +2.4 3/3 methods agree | Not in label — unassessed | serious PRR 6.1 · ♀ 0% (drug 39%) · 96% clinician | no trial data cached |
| Osteopenia | 39 | 9.0 6.6–12.4ROR 9.1 · χ² 270 / p 5e-61 | 8.5 EB05 6.4 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious PRR 6.1 | no trial data cached |
| Drug interaction | 405 | 9.0 8.2–9.9ROR 9.6 · χ² 2,895 / p <1e-300 | 8.9 EB05 8.2 · IC025 +3.0 3/3 methods agree | Reporting / coding artifact | serious PRR 5.9 · 91% clinician | no trial data cached |
| Drug level increased | 40 | 8.5 6.3–11.6ROR 8.6 · χ² 258 / p 2e-58 | 8.0 EB05 6.0 · IC025 +2.4 3/3 methods agree | Reporting / coding artifact | serious PRR 5.6 · ♀ 17% (drug 39%) · 95% clinician | 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 |
|---|---|---|---|---|---|---|
| Pyrexia (fever) | 462 | 4.7 4.3–5.1ROR 5.0 · χ² 1,367 / p 1e-299 | 4.7 EB05 4.3 · IC025 +2.1 3/3 methods agree | Labeled (related wording) related wording | serious PRR 3.5 | no trial data cached |
| Drug interaction | 405 | 9.0 8.2–9.9ROR 9.6 · χ² 2,895 / p <1e-300 | 8.9 EB05 8.2 · IC025 +3.0 3/3 methods agree | Reporting / coding artifact | serious PRR 5.9 · 91% clinician | no trial data cached |
| Vomiting | 371 | 2.8 2.5–3.1ROR 2.9 · χ² 434 / p 1e-96 | 2.8 EB05 2.6 · IC025 +1.3 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.5 · ♀ 70% (drug 39%) | no trial data cached |
| Treatment failure | 352 | 15.2 13.7–16.8ROR 16.1 · χ² 4,647 / p <1e-300 | 15.1 EB05 13.8 · IC025 +3.7 3/3 methods agree | Reporting / coding artifact | serious PRR 17.6 · ♀ 74% (drug 39%) · 97% clinician | no trial data cached |
| Rash | 339 | 2.8 2.5–3.1ROR 2.9 · χ² 386 / p 3e-86 | 2.7 EB05 2.5 · IC025 +1.3 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 3.5 · ♀ 74% (drug 39%) | no trial data cached |
| Foetal exposure during pregnancy | 338 | 14.7 13.3–16.3ROR 15.6 · χ² 4,309 / p <1e-300 | 14.6 EB05 13.4 · IC025 +3.7 3/3 methods agree | Reporting / coding artifact | serious PRR 9.0 | no trial data cached |
| Exposure during pregnancy | 299 | 17.0 15.2–19.0ROR 17.9 · χ² 4,487 / p <1e-300 | 16.9 EB05 15.4 · IC025 +3.9 3/3 methods agree | Reporting / coding artifact | serious PRR 14.2 · ♀ 100% (drug 39%) · 95% clinician | no trial data cached |
| Drug resistance | 292 | 40.5 36.2–45.4ROR 42.6 · χ² 11,105 / p <1e-300 | 40.0 EB05 36.3 · IC025 +5.0 3/3 methods agree | Reporting / coding artifact | serious PRR 26.8 · 91% clinician | no trial data cached |
| Pain | 276 | 1.6 1.4–1.8ROR 1.6 · χ² 60 / p 4e-15 | 1.6 EB05 1.4 · IC025 +0.5 | Labeled adverse reaction exact term | serious PRR 1.5 | no trial data cached |
| Hepatic enzyme increased | 257 | 13.4 11.9–15.1ROR 13.9 · χ² 2,930 / p <1e-300 | 13.3 EB05 12.0 · IC025 +3.5 3/3 methods agree | Labeled (related wording) related wording | serious PRR 11.6 · ♀ 91% (drug 39%) · 94% clinician | no trial data cached |
| Thrombocytopenia (low platelets) | 256 | 8.1 7.2–9.1ROR 8.4 · χ² 1,594 / p <1e-300 | 8.0 EB05 7.2 · IC025 +2.8 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 5.1 · ♀ 83% (drug 39%) · 95% clinician | no trial data cached |
| Pneumonia (lung infection) | 235 | 2.6 2.3–2.9ROR 2.6 · χ² 226 / p 2e-51 | 2.6 EB05 2.3 · IC025 +1.1 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 1.6 · ♀ 79% (drug 39%) · 92% clinician | no trial data cached |
| Hypertension (high blood pressure) | 229 | 3.8 3.4–4.3ROR 3.9 · χ² 476 / p 7e-106 | 3.8 EB05 3.4 · IC025 +1.7 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.9 · ♀ 67% (drug 39%) | no trial data cached |
| Anaemia (low red blood cells) | 229 | 4.2 3.7–4.8ROR 4.4 · χ² 567 / p 1e-125 | 4.2 EB05 3.8 · IC025 +1.9 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.8 | no trial data cached |
| Treatment noncompliance | 216 | 14.1 12.3–16.0ROR 14.6 · χ² 2,606 / p <1e-300 | 14.0 EB05 12.5 · IC025 +3.5 3/3 methods agree | Reporting / coding artifact | serious PRR 12.4 · 97% clinician | 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.
- Schizophrenia — n=165, PRR 48.5
- Coeliac disease — n=105, PRR 38.1
- Bursitis — n=105, PRR 30.9
- Eyelid ptosis — n=75, PRR 26.2
- Prescribed overdose — n=120, PRR 22.0
- Nephropathy toxic — n=61, PRR 19.4
- Cholelithiasis — n=173, PRR 18.7
- Anhedonia — n=113, PRR 15.1
- Psychotic disorder — n=126, PRR 15.1
- Rash erythematous — n=192, PRR 14.5
✓ A hand-written Bradford Hill causality assessment exists for this drug: Abacavir ↔ Hypersensitivity reaction.
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 Abacavir?
In FDA FAERS, the most frequently co-reported reaction terms for Abacavir are pyrexia, vomiting, rash, pain, hepatic enzyme increased, thrombocytopenia. 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 Abacavir have an FDA boxed warning?
Yes. The current FDA label carries a boxed warning: HYPERSENSITIVITY REACTIONS WARNING: HYPERSENSITIVITY REACTIONS See full prescribing information for complete boxed warning. Serious and sometimes fatal hypersensitivity reactions have occurred with abacavir sulfate. ( 5.1 ) Hypersensitivity to abacavir is a multi-organ clinical syndrome.
Do FAERS signals prove that Abacavir 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 0d791375-e311-41f9-87b8-940657e6318c, effective 20201224; matched on
openfda.generic_name.exact:"ABACAVIR") - 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, 304 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.