Flu Treatment and Prevention: What Prescribers Need to Know

Top Takeaways

• Start antivirals ASAP for high-risk patients, even if it’s after 48 hours.
• Stick with oseltamivir for most high-risk patients. Baloxavir is a one-dose option for eligible outpatients.
• Save prophylaxis for select exposed patients the flu vaccine isn’t protecting...and start it within 48 hours.

Patients will look to you to sort out if they need a flu antiviral...with an early surge in influenza in some parts of the US.

Treat high-risk patients ASAP. Prescribe an antiviral for suspected or confirmed flu in patients at high risk for complications...such as kids under age 5, adults 65 and up, patients who are immunocompromised or pregnant, and those with chronic conditions (diabetes, lung disease, etc).

Don’t wait for a positive test when flu is circulating...and don’t let a negative rapid antigen test rule out flu. Plus, still treat these patients if symptoms started MORE than 48 hours ago.

For otherwise healthy patients, use shared decision-making. Treatment can shorten symptoms by about a day if started within 48 hours.

Stick with oseltamivir for most high-risk patients. It has the most data and is preferred in pregnancy, severe illness, and young kids. It costs about $20 for 5 days. Advise taking it with food...to limit nausea.

Prescribe 75 mg twice daily for 5 days for most patients age 13 and up. Keep in mind to reduce the dose if eGFR is 60 mL/min or less.

Use weight-based doses for younger kids. For infants 9 to 11 months, the American Academy of Pediatrics recommends 3.5 mg/kg twice daily...higher than CDC’s 3 mg/kg...to reach higher levels.

Stay tuned. There’s a preprint study that shows oseltamivir isn’t effective and may worsen outcomes in patients who are critically ill with influenza...versus placebo. We’re awaiting peer review and publication.

Consider baloxavir as a one-dose option. It seems to work as well as oseltamivir for uncomplicated flu...with less nausea. It’s approved for patients age 5 and up.

Keep in mind, it’s not recommended in pregnancy, breastfeeding, or patients who are severely ill or immunocompromised. Data are lacking.

Tell patients not to take it with dairy, antacids, or supplements with calcium, iron, magnesium, or zinc...these can lower absorption.

Don’t expect to see generic baloxavir yet. It’s FDA-approved, but launch depends on patent issues. Brand Xofluza costs about $170 per dose.

Reserve inhaled zanamivir (Relenza) for patients age 7 and up when oral options aren’t feasible...and avoid it in asthma or COPD.

Save post-exposure prophylaxis for select patients. Prescribe it for exposed residents during institutional outbreaks...unvaccinated household contacts of a high-risk person...and patients who are immunocompromised.

Get our chart, Antivirals for Influenza, for more specifics, such as which med to use and dosing and duration of prophylaxis.

Reinforce fluids, rest, handwashing, staying home when sick, etc.

Continue to encourage vaccination as long as flu is circulating. Use our Flu Vaccines for 2026-2027 chart for guidance.

• Chart: Flu Vaccines for 2026-27 (United States)
• Chart: Antivirals for Influenza