Which antiviral is commonly used to treat influenza when started early?

• A. Ribavirin
• B. Lamivudine
• C. Oseltamivir
• D. Zanamivir

Answer: (C)

Starting antiviral therapy for influenza as early as possible is most effective because these drugs work by blocking neuraminidase, an enzyme the virus needs to spread from infected cells to new ones. When started within about 48 hours of symptom onset, this approach can shorten illness and reduce the risk of complications, especially in people at higher risk.

Oseltamivir is the drug most commonly used for this purpose. It is taken orally, making it convenient for outpatient treatment, and it has proven effectiveness against both influenza A and B when started early. This convenience and broad activity explain why it’s the first-line choice in many clinical situations.

Ribavirin isn’t used routinely for influenza; it’s reserved for other viral infections (and some severe cases with specific indications), so it doesn’t fit the typical early influenza treatment pattern. Lamivudine is an antiviral targeting HIV and hepatitis B, not influenza. Zanamivir is also a neuraminidase inhibitor and can treat influenza, but it’s inhaled, which can limit its use in patients with asthma or COPD and in some outpatient settings, making oseltamivir the more common choice.