Contraindications for Tamiflu (Oseltamivir)
The only absolute contraindication to oseltamivir is known serious hypersensitivity to oseltamivir or any component of the formulation. 1
Absolute Contraindication
- Serious hypersensitivity reactions (including anaphylaxis, severe rash, or angioedema) to oseltamivir or any ingredient in the formulation represent the sole FDA-labeled contraindication. 1
Critical Dosing Adjustments (Not Contraindications, But Required Modifications)
Renal Impairment
- Creatinine clearance 30-60 mL/min: Reduce dose to 30 mg twice daily for treatment. 2
- Creatinine clearance 10-30 mL/min: Reduce dose to 75 mg once daily for treatment and 75 mg every other day for prophylaxis. 3, 2
- Routine dialysis patients: No established dosing recommendations exist; use with extreme caution. 3
- The active metabolite (oseltamivir carboxylate) accumulates significantly in renal impairment, increasing adverse reaction risk. 3, 2
Hepatic Dysfunction
- No dose adjustment or contraindication exists for liver disease, as oseltamivir has not been formally studied in hepatic dysfunction. 3, 4
- The CDC and ACIP explicitly state no specific warnings or contraindications for hepatic impairment. 4
- Metabolism occurs via hepatic esterases, but elimination is predominantly renal (80%), making hepatotoxicity unlikely at therapeutic doses. 4
Special Populations Requiring Heightened Monitoring (Not Contraindications)
Seizure Disorders
- Seizure events have been reported during postmarketing surveillance with oseltamivir, but no epidemiologic studies demonstrate increased seizure risk. 3
- Unlike amantadine (which shows clear increased seizure incidence), oseltamivir lacks definitive causality data. 3
- Proceed with oseltamivir in seizure patients when influenza treatment is indicated, as the mortality benefit outweighs theoretical seizure concerns. 3
Psychiatric Disorders
- Neuropsychiatric events (delirium, hallucinations, suicidal behavior, agitation) have been reported, particularly in children and adolescents. 5, 6
- These events occurred primarily in Japanese populations and may be confounded by influenza-associated encephalopathy itself. 5
- A 74-year-old with mild neurocognitive disorder developed new psychiatric symptoms on oseltamivir prophylaxis that resolved completely upon discontinuation. 6
- Psychiatric history is not a contraindication, but close monitoring is essential, especially in patients with pre-existing neurocognitive disorders. 6
Clinical Pitfalls to Avoid
- Do not withhold oseltamivir in high-risk patients (immunocompromised, chronic cardiac/respiratory disease, age >65, pregnancy, hospitalized) based on theoretical concerns about seizures or psychiatric effects—influenza mortality risk exceeds medication risk. 4
- Always calculate creatinine clearance rather than relying on serum creatinine alone, especially in elderly patients where renal function declines with age despite normal creatinine. 2
- Administer with food to reduce nausea and vomiting (occurs in 10-14% of patients) without affecting absorption. 2, 7, 8
- Initiate within 48 hours of symptom onset for maximum therapeutic benefit. 2