Drug · FAERS side-effect profile with label screen
Entecavir side effects: what 11,607 FDA adverse event reports show
Drug class
Hepatitis B Virus Nucleoside Analog Reverse Transcriptase Inhibitor
FDA label (Established Pharmacologic Class) · compare the class
Who reports
11,607 reports · 87% serious · 1,880 with death outcome · 35% female
openFDA FAERS counts, all years, deduplication not applied
Used for
Entecavir tablets are indicated for the treatment of chronic hepatitis B virus infection in adults and pediatric patients 2 years of age and older with evidence of active viral replication and either evidence of persistent elevations in serum aminotransferases (ALT or AST) or histologically active disease.
FDA label, Indications and Usage
What it is
Entecavir tablet USP, is a guanosine nucleoside analogue with selective activity against HBV.
FDA label, Description section
Boxed warning
SEVERE ACUTE EXACERBATIONS OF HEPATITIS B, PATIENTS CO-INFECTED WITH HIV AND HBV, AND LACTIC ACIDOSIS AND HEPATOMEGALY WARNING: SEVERE ACUTE EXACERBATIONS OF HEPATITIS B, PATIENTS CO-INFECTED WITH HIV AND HBV, and LA.
FDA 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
Labeled — boxed warning 3Labeled adverse reaction 4Labeled (related wording) 1Likely indication confounding 2Reporting / coding artifact 5Lab value / disease marker 9Not in label — unassessed 16
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. 990 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.
Show:
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Genotype drug resistance test | 30 | 2,813.1 1,583.9–4,996.1ROR 2,820.4 · χ² 31,619 / p <1e-300 | 641.7 EB05 471.2 · IC025 +5.2 3/3 methods agree | Reporting / coding artifact | serious n=30 · ♀ 0% (drug 35%) · 100% clinician | no trial data cached |
| Blood hiv rna decreased | 22 | 2,799.7 1,432.9–5,470.4ROR 2,805.0 · χ² 22,859 / p <1e-300 | 557.8 EB05 388.3 · IC025 +4.7 3/3 methods agree | Lab value / disease marker | serious n=22 | no trial data cached |
| Hepatitis b dna increased | 143 | 487.1 405.2–585.6ROR 493.2 · χ² 54,099 / p <1e-300 | 364.1 EB05 316.7 · IC025 +7.1 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious n=141 | no trial data cached |
| Hepatitis b dna assay positive | 10 | 153.6 80.5–292.9ROR 153.7 · χ² 1,259 / p 6e-276 | 111.9 EB05 65.0 · IC025 +3.1 3/3 methods agree | Lab value / disease marker | serious n=10 | no trial data cached |
| Hepatitis b surface antigen positive | 19 | 133.8 84.0–213.2ROR 134.0 · χ² 2,207 / p <1e-300 | 110.9 EB05 75.1 · IC025 +4.1 3/3 methods agree | Lab value / disease marker | serious n=19 | no trial data cached |
| Chronic hepatitis b | 18 | 109.8 68.3–176.7ROR 110.0 · χ² 1,727 / p <1e-300 | 93.5 EB05 62.6 · IC025 +4.0 3/3 methods agree | Labeled — boxed warning exact term | serious n=18 | no trial data cached |
| Exposure via body fluid | 43 | 103.7 76.3–140.9ROR 104.0 · χ² 4,035 / p <1e-300 | 94.0 EB05 72.7 · IC025 +5.0 3/3 methods agree | Reporting / coding artifact | serious n=35 · ♀ 100% (drug 35%) | no trial data cached |
| Hepatitis b | 329 | 103.6 92.9–115.6ROR 106.6 · χ² 31,515 / p <1e-300 | 97.5 EB05 88.9 · IC025 +6.2 3/3 methods agree | Labeled — boxed warning exact term | serious n=327 | no trial data cached |
| Hepatitis b reactivation | 167 | 100.2 85.8–117.0ROR 101.6 · χ² 15,433 / p <1e-300 | 93.9 EB05 82.5 · IC025 +6.0 3/3 methods agree | Labeled — boxed warning synonym match | serious n=167 · 95% clinician | no trial data cached |
| Acute hepatitis b | 17 | 96.5 59.2–157.1ROR 96.6 · χ² 1,434 / p <1e-300 | 83.3 EB05 55.1 · IC025 +3.9 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious n=17 | no trial data cached |
| Hepatic neoplasm malignant | 107 | 95.0 78.3–115.3ROR 95.9 · χ² 9,359 / p <1e-300 | 88.8 EB05 75.6 · IC025 +5.7 3/3 methods agree | Labeled (related wording) related wording | serious n=107 · ♀ 13% (drug 35%) | no trial data cached |
| Genotype drug resistance test positive | 47 | 85.6 63.9–114.7ROR 86.0 · χ² 3,670 / p <1e-300 | 79.2 EB05 62.0 · IC025 +5.0 3/3 methods agree | Lab value / disease marker | serious n=46 · 94% clinician | no trial data cached |
| Osteomalacia | 64 | 77.3 60.2–99.2ROR 77.7 · χ² 4,547 / p <1e-300 | 72.6 EB05 58.9 · IC025 +5.1 3/3 methods agree | Not in label — unassessed | serious n=64 | no trial data cached |
| Fanconi syndrome acquired | 70 | 75.2 59.3–95.5ROR 75.7 · χ² 4,848 / p <1e-300 | 70.9 EB05 58.0 · IC025 +5.2 3/3 methods agree | Not in label — unassessed | serious n=70 | no trial data cached |
| Hypouricaemia | 11 | 70.8 38.7–129.2ROR 70.8 · χ² 662 / p 3e-146 | 61.2 EB05 36.5 · IC025 +3.1 3/3 methods agree | Not in label — unassessed | serious n=11 | no trial data cached |
| Viral mutation identified | 131 | 66.1 55.5–78.6ROR 66.8 · χ² 8,033 / p <1e-300 | 63.2 EB05 54.6 · IC025 +5.4 3/3 methods agree | Not in label — unassessed | serious n=131 · 91% clinician | no trial data cached |
| Viral load increased | 127 | 60.7 50.9–72.4ROR 61.4 · χ² 7,156 / p <1e-300 | 58.3 EB05 50.2 · IC025 +5.3 3/3 methods agree | Lab value / disease marker | serious n=124 | no trial data cached |
| Fanconi syndrome | 44 | 58.4 43.3–78.8ROR 58.6 · χ² 2,347 / p <1e-300 | 55.3 EB05 42.9 · IC025 +4.6 3/3 methods agree | Not in label — unassessed | serious n=44 | no trial data cached |
| Alpha 1 foetoprotein increased | 21 | 54.7 35.4–84.4ROR 54.8 · χ² 1,023 / p 1e-224 | 50.8 EB05 35.1 · IC025 +3.9 3/3 methods agree | Lab value / disease marker | serious n=21 | no trial data cached |
| Hepatocellular carcinoma | 212 | 51.6 45.1–59.1ROR 52.5 · χ² 10,179 / p <1e-300 | 50.0 EB05 44.6 · IC025 +5.3 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 32.8 | no trial data cached |
| Hypoproteinaemia | 35 | 34.8 24.9–48.6ROR 34.9 · χ² 1,094 / p 3e-240 | 33.6 EB05 25.2 · IC025 +4.0 3/3 methods agree | Not in label — unassessed | serious n=35 · 94% clinician | no trial data cached |
| Multiple-drug resistance | 57 | 33.9 26.1–44.0ROR 34.0 · χ² 1,753 / p <1e-300 | 32.9 EB05 26.4 · IC025 +4.3 3/3 methods agree | Reporting / coding artifact | serious n=57 · ♀ 9% (drug 35%) | no trial data cached |
| Hypophosphataemia | 129 | 32.3 27.1–38.4ROR 32.6 · χ² 3,811 / p <1e-300 | 31.6 EB05 27.3 · IC025 +4.5 3/3 methods agree | Not in label — unassessed | serious PRR 21.9 | no trial data cached |
| Pathogen resistance | 144 | 29.0 24.6–34.2ROR 29.4 · χ² 3,808 / p <1e-300 | 28.5 EB05 24.8 · IC025 +4.4 3/3 methods agree | Reporting / coding artifact | serious PRR 19.8 | no trial data cached |
| Drug resistance | 402 | 28.7 26.1–31.6ROR 29.7 · χ² 10,567 / p <1e-300 | 28.2 EB05 26.0 · IC025 +4.6 3/3 methods agree | Reporting / coding artifact | serious PRR 20.9 | no trial data cached |
| Foetal hypokinesia | 10 | 26.6 14.2–49.6ROR 26.6 · χ² 218 / p 1e-49 | 24.9 EB05 14.1 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious n=10 | no trial data cached |
| Oesophageal varices haemorrhage | 30 | 25.2 17.6–36.2ROR 25.3 · χ² 665 / p 6e-147 | 24.6 EB05 18.0 · IC025 +3.6 3/3 methods agree | Not in label — unassessed | serious n=30 · 90% clinician | no trial data cached |
| Blood phosphorus decreased | 50 | 25.1 19.0–33.2ROR 25.3 · χ² 1,120 / p 8e-246 | 24.6 EB05 19.4 · IC025 +3.9 3/3 methods agree | Lab value / disease marker | serious n=49 | no trial data cached |
| Disseminated cryptococcosis | 10 | 24.9 13.3–46.4ROR 24.9 · χ² 203 / p 2e-46 | 23.3 EB05 13.1 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious n=10 | no trial data cached |
| Urine protein/creatinine ratio increased | 12 | 24.7 14.0–43.6ROR 24.7 · χ² 246 / p 1e-55 | 23.4 EB05 14.0 · IC025 +2.7 3/3 methods agree | Lab value / disease marker | serious n=12 | no trial data cached |
| Mycoplasma infection | 10 | 23.6 12.6–44.0ROR 23.6 · χ² 192 / p 6e-44 | 22.1 EB05 12.3 · IC025 +2.4 3/3 methods agree | Not in label — unassessed | serious n=10 | no trial data cached |
| Hepatorenal syndrome | 21 | 22.6 14.7–34.8ROR 22.7 · χ² 408 / p 6e-91 | 21.9 EB05 15.1 · IC025 +3.2 3/3 methods agree | Labeled adverse reaction exact term | serious n=21 · 100% clinician | no trial data cached |
| Foetal heart rate abnormal | 11 | 21.7 12.0–39.3ROR 21.7 · χ² 195 / p 2e-44 | 20.4 EB05 11.6 · IC025 +2.5 3/3 methods agree | Lab value / disease marker | serious n=11 | no trial data cached |
| Cancer surgery | 11 | 21.0 11.6–38.1ROR 21.0 · χ² 188 / p 5e-43 | 19.8 EB05 11.1 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious n=11 | no trial data cached |
| Hepatic encephalopathy | 107 | 20.9 17.3–25.3ROR 21.1 · χ² 1,988 / p <1e-300 | 20.6 EB05 17.5 · IC025 +3.9 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 13.7 · 91% clinician | no trial data cached |
| Renal tubular atrophy | 10 | 20.9 11.2–38.9ROR 20.9 · χ² 168 / p 1e-38 | 19.5 EB05 10.5 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious n=10 | no trial data cached |
| Portal vein thrombosis | 35 | 19.8 14.2–27.7ROR 19.9 · χ² 601 / p 5e-133 | 19.4 EB05 14.6 · IC025 +3.4 3/3 methods agree | Not in label — unassessed | serious n=35 | no trial data cached |
| Liver transplant | 38 | 19.1 13.9–26.3ROR 19.2 · χ² 629 / p 5e-139 | 18.8 EB05 14.2 · IC025 +3.4 3/3 methods agree | Labeled adverse reaction exact term | serious n=38 | no trial data cached |
| Renal tubular injury | 12 | 18.9 10.7–33.4ROR 18.9 · χ² 184 / p 3e-42 | 17.8 EB05 10.1 · IC025 +2.5 3/3 methods agree | Not in label — unassessed | serious n=12 | no trial data cached |
| Optic neuropathy | 21 | 18.3 11.9–28.1ROR 18.3 · χ² 322 / p 2e-72 | 17.7 EB05 12.0 · IC025 +3.0 3/3 methods agree | Not in label — unassessed | serious n=21 · 100% clinician | 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 |
|---|---|---|---|---|---|---|
| Death | 550 | 1.2 1.1–1.3ROR 1.2 · χ² 12 / p 3e-4 | 1.2 EB05 1.1 · IC025 +0.1 | Outcome field, not a reaction boxed warning mentions mortality | serious PRR 0.8 | no trial data cached |
| Off label use (used outside approved label) | 536 | 1.1 1.0–1.2ROR 1.1 · χ² 7 / p 0.005 | 1.1 EB05 1.0 · IC025 +0.0 | Reporting / coding artifact | serious PRR 1.2 | no trial data cached |
| Drug ineffective (drug did not work) | 443 | 0.6 0.6–0.7ROR 0.6 · χ² 119 / p 5e-28 | 0.6 EB05 0.6 · IC025 -0.9 PRR-only: not supported by EBGM or IC | Reporting / coding artifact | serious PRR 1.0 | no trial data cached |
| Drug resistance | 402 | 28.7 26.1–31.6ROR 29.7 · χ² 10,567 / p <1e-300 | 28.2 EB05 26.0 · IC025 +4.6 3/3 methods agree | Reporting / coding artifact | serious PRR 20.9 | no trial data cached |
| Diarrhoea (diarrhea) | 376 | 1.1 1.0–1.2ROR 1.1 · χ² 1 / p 0.148 | 1.1 EB05 1.0 · IC025 -0.1 PRR-only: not supported by EBGM or IC | Labeled adverse reaction exact term | serious PRR 1.0 | no trial data cached |
| Pyrexia (fever) | 365 | 1.9 1.7–2.1ROR 1.9 · χ² 159 / p 1e-36 | 1.9 EB05 1.7 · IC025 +0.8 | Labeled adverse reaction exact term | serious PRR 1.5 | no trial data cached |
| Fatigue (tiredness) | 363 | 0.8 0.8–0.9ROR 0.8 · χ² 11 / p 5e-4 | 0.8 EB05 0.8 · IC025 -0.4 PRR-only: not supported by EBGM or IC | Labeled adverse reaction exact term | serious PRR 0.7 | no trial data cached |
| Hepatitis b | 329 | 103.6 92.9–115.6ROR 106.6 · χ² 31,515 / p <1e-300 | 97.5 EB05 88.9 · IC025 +6.2 3/3 methods agree | Labeled — boxed warning exact term | serious n=327 | no trial data cached |
| Nausea | 325 | 0.7 0.7–0.8ROR 0.7 · χ² 29 / p 3e-8 | 0.7 EB05 0.7 · IC025 -0.6 PRR-only: not supported by EBGM or IC | Labeled adverse reaction exact term | serious PRR 0.8 | no trial data cached |
| Pneumonia (lung infection) | 302 | 1.7 1.5–1.9ROR 1.7 · χ² 85 / p 1e-20 | 1.7 EB05 1.5 · IC025 +0.6 | Labeled — boxed warning synonym match | serious PRR 1.1 | no trial data cached |
| Platelet count decreased | 301 | 5.1 4.6–5.7ROR 5.2 · χ² 995 / p 1e-218 | 5.1 EB05 4.6 · IC025 +2.2 3/3 methods agree | Labeled (related wording) related wording | serious PRR 3.9 | no trial data cached |
| Anaemia (low red blood cells) | 236 | 2.2 2.0–2.5ROR 2.3 · χ² 161 / p 3e-37 | 2.2 EB05 2.0 · IC025 +0.9 | Not in label — unassessed | serious PRR 1.6 | no trial data cached |
| Renal impairment | 232 | 5.0 4.4–5.7ROR 5.1 · χ² 744 / p 5e-164 | 5.0 EB05 4.4 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious PRR 3.4 | no trial data cached |
| Hepatic failure | 230 | 13.8 12.2–15.7ROR 14.1 · χ² 2,711 / p <1e-300 | 13.7 EB05 12.3 · IC025 +3.5 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 9.1 | no trial data cached |
| White blood cell count decreased | 227 | 3.8 3.3–4.3ROR 3.8 · χ² 464 / p 4e-103 | 3.8 EB05 3.4 · IC025 +1.7 3/3 methods agree | Lab value / disease marker | serious PRR 3.2 | 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.
- Osteomalacia — n=64, PRR 77.3
- Fanconi syndrome acquired — n=70, PRR 75.2
- Viral mutation identified — n=131, PRR 66.1
- Fanconi syndrome — n=44, PRR 58.4
- Hypoproteinaemia — n=35, PRR 34.8
- Hypophosphataemia — n=129, PRR 32.3
- Oesophageal varices haemorrhage — n=30, PRR 25.2
- Portal vein thrombosis — n=35, PRR 19.8
- Optic neuropathy — n=21, PRR 18.3
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 Entecavir?
In FDA FAERS, the most frequently co-reported reaction terms for Entecavir are diarrhoea, pyrexia, fatigue, hepatitis b, nausea, pneumonia. 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 Entecavir have an FDA boxed warning?
Yes. The current FDA label carries a boxed warning: SEVERE ACUTE EXACERBATIONS OF HEPATITIS B, PATIENTS CO-INFECTED WITH HIV AND HBV, AND LACTIC ACIDOSIS AND HEPATOMEGALY WARNING: SEVERE ACUTE EXACERBATIONS OF HEPATITIS B, PATIENTS CO-INFECTED WITH HIV AND HBV, and LA.
Do FAERS signals prove that Entecavir 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 01ec50a1-6c6c-46f0-8c74-73542b0a59c3, effective 20250109; matched on
openfda.generic_name.exact:"ENTECAVIR") - 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, 1,030 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.