What are the contraindications and side effects of Xofluza (Baloxavir) and Tamiflu (Oseltamivir) in teenage patients with influenza?

Xofluza and Tamiflu: Contraindications and Side Effects in Teenage Patients

Contraindications

Xofluza (Baloxavir)

Xofluza is contraindicated only in patients with a history of hypersensitivity to baloxavir marboxil or any of its ingredients. 1

• Hypersensitivity reactions can include anaphylaxis, angioedema, urticaria, and erythema multiforme 1
• Critical drug interaction: Avoid coadministration with dairy products, calcium-fortified beverages, polyvalent cation-containing laxatives, antacids, or oral supplements containing calcium, iron, magnesium, selenium, or zinc 1, 2
• These products significantly reduce baloxavir's antiviral efficacy and must be avoided during treatment 2

Tamiflu (Oseltamivir)

Oseltamivir has no absolute contraindications in the FDA labeling for teenage patients. 3

• Hypersensitivity reactions including anaphylaxis have been reported postmarketing, though no formal contraindication exists 3
• Dose adjustment required in patients with renal insufficiency based on creatinine clearance 3

Side Effects

Xofluza (Baloxavir) in Adolescents (12+ years)

The most common adverse effects in adolescents and adults treated with Xofluza are diarrhea (3%), bronchitis (3%), nausea (2%), sinusitis (2%), and headache (1%). 1

• Serious allergic reactions can occur: Get emergency help if trouble breathing, skin rash/hives/blisters, swelling of face/throat/mouth, or dizziness/lightheadedness develops 1
• These side effects are generally mild and self-limited 1

Tamiflu (Oseltamivir) in Adolescents

The most common adverse effect of oseltamivir in teenage patients is vomiting, occurring in approximately 15% of treated patients versus 9% receiving placebo. 3

• Other common side effects include nausea, headache, skin reactions, and diarrhea 3
• Important safety note: Despite reports from Japan of neuropsychiatric adverse effects, extensive review of controlled clinical trial data and ongoing surveillance has failed to establish a link between oseltamivir and neurologic or psychiatric events 3
• Vomiting is transient and rarely leads to treatment discontinuation 4
• Nausea can be managed with mild anti-emetic medication and may be reduced by taking oseltamivir with meals 3

Key Clinical Considerations for Teenagers

Treatment Timing

Both medications should be initiated within 48 hours of symptom onset for optimal benefit, though treatment beyond 48 hours still provides substantial benefit in high-risk or severely ill patients. 3, 4

Dosing for Teenagers

For Xofluza: Teenagers weighing 20-80 kg receive one 40 mg tablet as a single dose; those ≥80 kg receive one 80 mg tablet as a single dose 1

For Tamiflu: Teenagers >40 kg receive 75 mg twice daily for 5 days 3

Important Pitfall to Avoid

Do not administer Xofluza with dairy products, calcium supplements, or antacids—this is the most critical drug interaction that significantly reduces efficacy. 1, 2 This differs from oseltamivir, which can be taken with or without food and has no such restrictions 3

Comparative Safety Profile

Both medications are generally well-tolerated in teenagers. Oseltamivir has more extensive safety data in pediatric populations due to longer clinical experience 3, while Xofluza offers the advantage of single-dose administration, which may improve compliance 3. The gastrointestinal side effects (vomiting with oseltamivir, diarrhea with baloxavir) are the most common adverse events but are typically mild and self-limited 3, 1.