What is the treatment for an allergic reaction to Tamiflu (oseltamivir)?

Management of Allergic Reactions to Tamiflu (Oseltamivir)

Immediately discontinue oseltamivir and do not rechallenge the patient if an allergic reaction occurs or is suspected. 1

Immediate Management Based on Reaction Severity

Serious Hypersensitivity Reactions (Anaphylaxis, Severe Skin Reactions)

• Stop oseltamivir immediately and institute appropriate emergency treatment if the patient develops anaphylaxis, toxic epidermal necrolysis, Stevens-Johnson Syndrome, or erythema multiforme. 1

• These severe reactions have been reported in postmarketing surveillance and constitute absolute contraindications to future oseltamivir use. 1

• Anaphylaxis requires standard emergency protocols: epinephrine, airway management, IV fluids, antihistamines, and corticosteroids as clinically indicated. 1

• Severe skin reactions (toxic epidermal necrolysis, Stevens-Johnson Syndrome, erythema multiforme) require immediate dermatology consultation, wound care, and often hospitalization. 1, 2

Mild to Moderate Allergic Reactions

• For less severe skin reactions (rash, urticaria without systemic symptoms), discontinue oseltamivir and provide symptomatic treatment with antihistamines. 1

• Monitor closely for progression to more severe reactions over the next 24-48 hours. 1

Alternative Antiviral Options After Oseltamivir Allergy

Zanamivir (Inhaled Neuraminidase Inhibitor)

• Zanamivir 10 mg (two 5-mg inhalations) twice daily is the preferred alternative for patients who cannot tolerate oseltamivir, as it is a different formulation with distinct excipients. 3

• Approved for adults and children ≥7 years for treatment, and ≥5 years for prophylaxis. 3

• Administer via oral inhalation using the provided Diskhaler device. 3

Peramivir (Intravenous Neuraminidase Inhibitor)

• Peramivir is an IV alternative for patients requiring parenteral therapy or those unable to take oral/inhaled medications. 4

• Adult dosing: 600 mg as a single IV infusion over 15-30 minutes. 4

• Pediatric dosing (2-12 years): 12 mg/kg (maximum 600 mg) as a single IV infusion. 4

• Note that peramivir is approved only for treatment, not prophylaxis. 4

Critical Clinical Considerations

Contraindication Documentation

• Oseltamivir is absolutely contraindicated in patients with known serious hypersensitivity to oseltamivir or any component of the product. 1

• Document the allergic reaction clearly in the medical record to prevent future inadvertent exposure. 1

Timing of Alternative Therapy

• If the allergic reaction occurs early in the treatment course and influenza treatment is still indicated, initiate alternative antiviral therapy (zanamivir or peramivir) immediately. 3, 4

• Treatment efficacy is maximized when started within 48 hours of symptom onset, so do not delay switching to an alternative agent. 4

Common Pitfalls to Avoid

• Do not confuse gastrointestinal side effects (nausea, vomiting) with true allergic reactions—these are common adverse effects occurring in 5-15% of patients and do not require discontinuation unless severe. 5, 1

• Do not attempt dose reduction or rechallenge in patients with documented serious hypersensitivity reactions. 1

• Ensure the alternative agent (zanamivir or peramivir) is appropriate for the patient's age and clinical situation before prescribing. 3, 4

Prophylaxis Considerations

• If the allergic reaction occurred during prophylaxis rather than treatment, consider whether continued prophylaxis is necessary based on exposure risk. 3

• Zanamivir can be used for prophylaxis at 10 mg once daily in patients ≥5 years who had allergic reactions to oseltamivir. 3