Neuraminidase inhibitors
ATC code: J05AH02 (Oseltamivir)
Prodrug. Converted in the liver to oseltamivir carboxylate, which selectively inhibits influenza A and B neuraminidase. Neuraminidase cleaves sialic acid residues on infected cell surfaces, and without it viral particles cannot bud off. The drug blocks this step and reduces viral spread.
First line
First-line antiviral for influenza in adults and children. RCTs show that starting treatment within 48 hours of symptom onset shortens illness by 1–2 days and reduces complication risk. In hospitalized patients and high-risk groups – pregnant, elderly, immunocompromised – treatment is started even beyond 48 hours.
Not recommended
Not effective against COVID-19. Oseltamivir inhibits neuraminidase, which SARS-CoV-2 lacks. The virus uses spike protein and ACE2 receptor for cell entry – an entirely different mechanism. Early oseltamivir prescriptions during COVID were driven by diagnostic uncertainty when influenza had not been ruled out.
FDA category C. However, CDC and ACOG recommend oseltamivir for pregnant women with confirmed or suspected influenza. The benefit from reducing influenza complications during pregnancy outweighs the theoretical risk.
oseltamivir is evaluated for the following indications with varying evidence strength: Influenza (evidence tier A), COVID-19 (evidence tier F). See the full indication matrix with dosing and citations above on this page.
Common side effects of oseltamivir (≥ 1 in 100): Nausea, Vomiting, Headache. See the Safety section for uncommon and serious reactions.
FDA category C. FDA category C. However, CDC and ACOG recommend oseltamivir for pregnant women with confirmed or suspected influenza. The benefit from reducing influenza complications during pregnancy outweighs the theoretical risk.
oseltamivir is contraindicated in: Hypersensitivity to oseltamivir. Full list in the Safety section.
the 2014 Cochrane review did find limited impact on complications, but the original RCTs were not powered for that endpoint. Meta-analyses of observational data show reduced mortality in hospitalized patients. CDC, IDSA, and WHO still recommend oseltamivir for influenza treatment.