Oseltamivir Phosphate side effects: what 24,273 FDA adverse event reports show
Drug class
Influenza neuraminidase inhibitor (nai)
Who reports
24,273 reports · 65% serious · 2,714 with death outcome · 56% female
Used for
Oseltamivir phosphate capsule is an influenza neuraminidase inhibitor (NAI) indicated for: Treatment of acute, uncomplicated influenza A and B in patients 2 weeks of age and older who have been symptomatic for no more than 48 hours. ( 1.1 ) Prophylaxis of influenza A and B in patients 1 year and older. ( 1.2 ) Limitations of Use : Not a substitute for annual influenza vaccination.
What it is
Oseltamivir phosphate capsules, USP, an influenza neuraminidase inhibitor (NAI), are available as capsules containing 30 mg, 45 mg, or 75 mg of oseltamivir for oral use, in the form of oseltamivir phosphate, USP.
Boxed warning
None in the current label
Causality screen of the 40 strongest signals
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.
- 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, for the 300 most-reported drugs, adjusted for age band), and flags pairs whose reports are unusually skewed by sex or come mostly from consumers. Each row also shows the PRR against the other drugs of the same FDA class, which removes most confounding by the condition being treated, and a calibrated p-value: on validation, known non-causes average an ROR of about 2, so significance is judged against that empirical null (✓ = p < 0.05 after calibration). 1,074 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 |
|---|---|---|---|---|---|---|
| Antacid therapy | 76 | 1,504.4 1,035.2–2,186.3ROR 1,509.1 · calibrated p 2e-18 ✓ | 478.4 EB05 394.7 · IC025 +6.5 3/3 methods agree | Reporting / coding artifact | serious n=76 · ♀ 23% (drug 56%) · 100% clinician | no trial data cached |
| Appendicolith | 225 | 1,276.8 1,038.9–1,569.2ROR 1,288.7 · calibrated p 3e-18 ✓ | 489.9 EB05 438.5 · IC025 +7.7 3/3 methods agree | Not in label — unassessed | serious n=225 · ♀ 8% (drug 56%) · 96% clinician | no trial data cached |
| Sleep disorder therapy | 110 | 1,265.3 942.6–1,698.4ROR 1,271.0 · calibrated p 7e-18 ✓ | 467.8 EB05 398.9 · IC025 +7.0 3/3 methods agree | Reporting / coding artifact | serious n=110 · ♀ 6% (drug 56%) · 100% clinician | no trial data cached |
| Analgesic therapy | 123 | 581.6 462.6–731.3ROR 584.6 · calibrated p 2e-14 ✓ | 328.3 EB05 282.4 · IC025 +6.9 3/3 methods agree | Reporting / coding artifact | serious n=123 · ♀ 15% (drug 56%) · 96% clinician | no trial data cached |
| Drug therapy | 117 | 500.4 398.4–628.6ROR 502.9 · calibrated p 1e-13 ✓ | 300.0 EB05 257.1 · IC025 +6.8 3/3 methods agree | Reporting / coding artifact | serious n=117 · ♀ 15% (drug 56%) · 96% clinician | no trial data cached |
| Anticoagulant therapy | 74 | 314.9 241.3–411.1ROR 315.9 · calibrated p 1e-11 ✓ | 217.3 EB05 178.8 · IC025 +6.1 3/3 methods agree | Reporting / coding artifact | serious n=74 · ♀ 24% (drug 56%) · 100% clinician | no trial data cached |
| Malignant melanoma stage 0 | 47 | 303.1 217.3–422.7ROR 303.7 · calibrated p 3e-11 ✓ | 205.2 EB05 160.5 · IC025 +5.6 3/3 methods agree | Not in label — unassessed | serious n=47 · ♀ 0% (drug 56%) · 100% clinician | no trial data cached |
| Congenital hiatus hernia | 50 | 251.8 183.7–345.2ROR 252.3 · calibrated p 1e-10 ✓ | 181.2 EB05 142.8 · IC025 +5.6 3/3 methods agree | Not in label — unassessed | serious n=50 · ♀ 0% (drug 56%) · 100% clinician | no trial data cached |
| Bacteroides infection | 39 | 153.0 108.8–215.1ROR 153.2 · calibrated p 1e-8 ✓ | 122.2 EB05 93.3 · IC025 +5.1 3/3 methods agree | Not in label — unassessed | serious n=39 · ♀ 0% (drug 56%) · 100% clinician | no trial data cached |
| Hepatitis infectious mononucleosis | 12 | 121.6 66.4–222.6ROR 121.7 · calibrated p 3e-7 ✓ | 91.5 EB05 55.8 · IC025 +3.4 3/3 methods agree | Not in label — unassessed | serious n=12 | no trial data cached |
| Pulmonary function test abnormal | 179 | 111.8 95.7–130.6ROR 112.6 · calibrated p 5e-8 ✓ | 97.9 EB05 86.5 · IC025 +6.0 3/3 methods agree | Reporting / coding artifact | serious n=179 · ♀ 100% (drug 56%) | no trial data cached |
| Delirium febrile | 10 | 90.6 47.2–173.8ROR 90.6 · calibrated p 3e-6 ✓ | 71.3 EB05 41.4 · IC025 +3.0 3/3 methods agree | Not in label — unassessed | serious n=10 | no trial data cached |
| Influenza virus test positive | 20 | 89.6 56.5–142.0ROR 89.7 · calibrated p 9e-7 ✓ | 75.5 EB05 51.6 · IC025 +4.0 3/3 methods agree | Lab value / disease marker | – | no trial data cached |
| Purpura senile | 11 | 87.5 47.1–162.7ROR 87.5 · calibrated p 3e-6 ✓ | 70.2 EB05 41.8 · IC025 +3.1 3/3 methods agree | Not in label — unassessed | serious n=11 | no trial data cached |
| H1n1 influenza | 109 | 72.1 59.3–87.6ROR 72.4 · calibrated p 1e-6 ✓ | 65.8 EB05 56.1 · IC025 +5.4 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious n=104 | no trial data cached |
| Influenza a virus test positive | 33 | 71.3 50.0–101.7ROR 71.4 · calibrated p 3e-6 ✓ | 63.5 EB05 47.4 · IC025 +4.5 3/3 methods agree | Lab value / disease marker | serious n=28 | no trial data cached |
| Hyperphosphataemia | 159 | 70.0 59.6–82.3ROR 70.5 · calibrated p 2e-6 ✓ | 64.3 EB05 56.3 · IC025 +5.5 3/3 methods agree | Not in label — unassessed | serious n=159 · ♀ 14% (drug 56%) · 97% clinician | no trial data cached |
| Blood phosphorus increased | 190 | 64.7 55.8–74.9ROR 65.2 · calibrated p 3e-6 ✓ | 59.8 EB05 53.0 · IC025 +5.5 3/3 methods agree | Lab value / disease marker | serious n=189 · ♀ 10% (drug 56%) · 95% clinician | no trial data cached |
| Chest x-ray abnormal | 215 | 64.3 56.0–73.9ROR 64.9 · calibrated p 3e-6 ✓ | 59.6 EB05 53.2 · IC025 +5.5 3/3 methods agree | Lab value / disease marker | serious n=215 · ♀ 100% (drug 56%) | no trial data cached |
| Normal newborn | 371 | 63.3 57.0–70.2ROR 64.2 · calibrated p 3e-6 ✓ | 58.8 EB05 53.9 · IC025 +5.6 3/3 methods agree | Not in label — unassessed | serious n=32 · 92% clinician | no trial data cached |
| Ear pruritus | 207 | 54.6 47.4–62.8ROR 55.0 · calibrated p 8e-6 ✓ | 51.1 EB05 45.5 · IC025 +5.3 3/3 methods agree | Not in label — unassessed | serious n=205 · ♀ 100% (drug 56%) | no trial data cached |
| Breath sounds abnormal | 249 | 45.9 40.4–52.1ROR 46.3 · calibrated p 2e-5 ✓ | 43.4 EB05 39.1 · IC025 +5.1 3/3 methods agree | Not in label — unassessed | serious n=248 · ♀ 86% (drug 56%) | no trial data cached |
| Pneumonia influenzal | 57 | 43.2 33.1–56.4ROR 43.3 · calibrated p 4e-5 ✓ | 40.6 EB05 32.5 · IC025 +4.5 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious n=57 | no trial data cached |
| Bronchopulmonary aspergillosis allergic | 43 | 42.5 31.3–57.7ROR 42.5 · calibrated p 5e-5 ✓ | 39.8 EB05 30.8 · IC025 +4.3 3/3 methods agree | Not in label — unassessed | serious n=43 · ♀ 0% (drug 56%) · 100% clinician | no trial data cached |
| Tarsal tunnel syndrome | 10 | 40.9 21.7–77.2ROR 40.9 · calibrated p 2e-4 ✓ | 36.6 EB05 21.2 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious n=10 | no trial data cached |
| Rhinitis allergic | 197 | 40.0 34.7–46.2ROR 40.4 · calibrated p 5e-5 ✓ | 38.2 EB05 33.9 · IC025 +4.9 3/3 methods agree | Not in label — unassessed | serious n=195 · ♀ 97% (drug 56%) | no trial data cached |
| Blood lactic acid increased | 209 | 35.8 31.2–41.1ROR 36.1 · calibrated p 1e-4 ✓ | 34.3 EB05 30.6 · IC025 +4.8 3/3 methods agree | Lab value / disease marker | serious n=208 · ♀ 100% (drug 56%) | no trial data cached |
| Nasal polyps | 182 | 33.8 29.2–39.2ROR 34.1 · calibrated p 1e-4 ✓ | 32.5 EB05 28.7 · IC025 +4.7 3/3 methods agree | Not in label — unassessed | serious n=182 · ♀ 100% (drug 56%) | no trial data cached |
| Urinary tract inflammation | 13 | 32.5 18.7–56.6ROR 32.6 · calibrated p 4e-4 ✓ | 30.1 EB05 18.7 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious n=13 | no trial data cached |
| Enterocolitis haemorrhagic | 53 | 31.9 24.2–41.9ROR 31.9 · calibrated p 2e-4 ✓ | 30.5 EB05 24.2 · IC025 +4.1 3/3 methods agree | Not in label — unassessed | serious n=53 · ♀ 78% (drug 56%) · 100% clinician | no trial data cached |
| Total lung capacity decreased | 45 | 24.9 18.5–33.5ROR 25.0 · calibrated p 9e-4 ✓ | 24.0 EB05 18.7 · IC025 +3.8 3/3 methods agree | Not in label — unassessed | serious n=45 · ♀ 18% (drug 56%) · 100% clinician | no trial data cached |
| Blood uric acid increased | 149 | 22.9 19.5–26.9ROR 23.0 · calibrated p 0.001 ✓ | 22.2 EB05 19.4 · IC025 +4.1 3/3 methods agree | Lab value / disease marker | serious n=149 · ♀ 13% (drug 56%) · 97% clinician | no trial data cached |
| Appendicitis | 240 | 22.9 20.1–26.0ROR 23.1 · calibrated p 0.001 ✓ | 22.3 EB05 20.0 · IC025 +4.2 3/3 methods agree | Not in label — unassessed | serious PRR 19.8 · ♀ 11% (drug 56%) · 96% clinician | no trial data cached |
| Abnormal behaviour | 964 | 21.4 20.1–22.8ROR 22.2 · calibrated p 0.001 ✓ | 20.9 EB05 19.8 · IC025 +4.3 3/3 methods agree | Not in label — unassessed | serious PRR 22.0 | no trial data cached |
| Chronic kidney disease-mineral and bone disorder | 26 | 21.4 14.5–31.5ROR 21.4 · calibrated p 0.002 ✓ | 20.6 EB05 14.7 · IC025 +3.3 3/3 methods agree | Not in label — unassessed | serious n=26 | no trial data cached |
| Neuropsychological symptoms | 14 | 21.4 12.6–36.3ROR 21.4 · calibrated p 0.003 ✓ | 20.2 EB05 12.5 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious n=14 | no trial data cached |
| Iron deficiency | 106 | 21.1 17.4–25.5ROR 21.2 · calibrated p 0.002 ✓ | 20.5 EB05 17.4 · IC025 +3.9 3/3 methods agree | Not in label — unassessed | serious n=106 · ♀ 6% (drug 56%) · 95% clinician | no trial data cached |
| Full blood count abnormal | 247 | 20.7 18.3–23.5ROR 20.9 · calibrated p 0.002 ✓ | 20.2 EB05 18.2 · IC025 +4.1 3/3 methods agree | Lab value / disease marker | serious PRR 23.4 · ♀ 85% (drug 56%) | no trial data cached |
| Upper-airway cough syndrome | 191 | 20.6 17.8–23.8ROR 20.7 · calibrated p 0.002 ✓ | 20.1 EB05 17.8 · IC025 +4.0 3/3 methods agree | Not in label — unassessed | serious n=187 · ♀ 97% (drug 56%) | no trial data cached |
| Activated partial thromboplastin time prolonged | 116 | 20.2 16.8–24.2ROR 20.2 · calibrated p 0.002 ✓ | 19.7 EB05 16.8 · IC025 +3.9 3/3 methods agree | Lab value / disease marker | serious n=116 · ♀ 18% (drug 56%) · 97% 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 |
|---|---|---|---|---|---|---|
| Off label use (used outside approved label) | 2,145 | 2.1 2.1–2.2ROR 2.2 · calibrated p 0.928 | 2.1 EB05 2.1 · IC025 +1.0 3/3 methods agree | Reporting / coding artifact | serious PRR 2.4 · 91% clinician | no trial data cached |
| Vomiting | 2,082 | 3.8 3.7–4.0ROR 4.1 · calibrated p 0.357 | 3.8 EB05 3.7 · IC025 +1.9 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.3 | no trial data cached |
| No adverse event | 1,590 | 7.8 7.4–8.2ROR 8.3 · calibrated p 0.060 | 7.7 EB05 7.4 · IC025 +2.9 3/3 methods agree | Reporting / coding artifact | serious PRR 2.3 | no trial data cached |
| Nausea | 1,575 | 1.7 1.6–1.8ROR 1.8 · calibrated p 0.815 | 1.7 EB05 1.7 · IC025 +0.7 | Labeled adverse reaction exact term | serious PRR 1.6 | no trial data cached |
| Drug ineffective (drug did not work) | 1,309 | 0.9 0.8–0.9ROR 0.9 · calibrated p 0.213 | 0.9 EB05 0.8 · IC025 -0.3 PRR-only: not supported by EBGM or IC | Reporting / coding artifact | serious PRR 1.6 | no trial data cached |
| Influenza | 1,197 | 9.3 8.8–9.9ROR 9.8 · calibrated p 0.035 ✓ | 9.2 EB05 8.8 · IC025 +3.1 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious PRR 8.8 | no trial data cached |
| Diarrhoea (diarrhea) | 1,044 | 1.4 1.3–1.5ROR 1.4 · calibrated p 0.589 | 1.4 EB05 1.3 · IC025 +0.4 | Labeled adverse reaction exact term | serious PRR 1.2 | no trial data cached |
| Dyspnoea (shortness of breath) | 1,012 | 1.5 1.5–1.6ROR 1.6 · calibrated p 0.687 | 1.5 EB05 1.5 · IC025 +0.5 | Not in label — unassessed | serious PRR 1.7 | no trial data cached |
| Abnormal behaviour | 964 | 21.4 20.1–22.8ROR 22.2 · calibrated p 0.001 ✓ | 20.9 EB05 19.8 · IC025 +4.3 3/3 methods agree | Not in label — unassessed | serious PRR 22.0 | no trial data cached |
| Headache | 959 | 1.3 1.2–1.4ROR 1.3 · calibrated p 0.533 | 1.3 EB05 1.3 · IC025 +0.3 | Labeled adverse reaction exact term | serious PRR 1.7 | no trial data cached |
| Pyrexia (fever) | 929 | 2.3 2.2–2.5ROR 2.4 · calibrated p 0.869 | 2.3 EB05 2.2 · IC025 +1.1 3/3 methods agree | Not in label — unassessed | serious PRR 1.9 | no trial data cached |
| Pneumonia (lung infection) | 918 | 2.5 2.3–2.6ROR 2.5 · calibrated p 0.807 | 2.5 EB05 2.3 · IC025 +1.2 3/3 methods agree | Labeled (related wording) related wording | serious PRR 2.2 | no trial data cached |
| Hallucination (hallucinations) | 879 | 10.2 9.6–10.9ROR 10.6 · calibrated p 0.027 ✓ | 10.1 EB05 9.6 · IC025 +3.2 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 8.8 | no trial data cached |
| Rash | 735 | 1.5 1.4–1.6ROR 1.5 · calibrated p 0.628 | 1.5 EB05 1.4 · IC025 +0.4 | Labeled adverse reaction exact term | serious PRR 1.5 | no trial data cached |
| Cough | 666 | 2.1 1.9–2.2ROR 2.1 · calibrated p 0.991 | 2.1 EB05 1.9 · IC025 +0.9 | Not in label — unassessed | serious PRR 2.4 | 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.
- Appendicolith — n=225, PRR 1,276.8
- Malignant melanoma stage 0 — n=47, PRR 303.1
- Congenital hiatus hernia — n=50, PRR 251.8
- Bacteroides infection — n=39, PRR 153.0
- Hyperphosphataemia — n=159, PRR 70.0
- Normal newborn — n=371, PRR 63.3
- Ear pruritus — n=207, PRR 54.6
- Breath sounds abnormal — n=249, PRR 45.9
- Bronchopulmonary aspergillosis allergic — n=43, PRR 42.5
- Rhinitis allergic — n=197, PRR 40.0
✓ A hand-written Bradford Hill causality assessment exists for this drug: Oseltamivir ↔ Neuropsychiatric events.
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 Oseltamivir?
In FDA FAERS, the most frequently co-reported reaction terms for Oseltamivir are vomiting, nausea, influenza, diarrhoea, dyspnoea, abnormal behaviour. 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 Oseltamivir have an FDA boxed warning?
No. The FDA label retrieved for Oseltamivir has no boxed warning; see the label's Warnings and Precautions for the recognised risks.
Do FAERS signals prove that Oseltamivir 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 82685c2f-791b-440f-a1c2-5a032da7adca, effective 20250730; matched on
openfda.generic_name.exact:"OSELTAMIVIR") - 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, 1,114 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 2026-10-14. 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.