Zanamivir, a neuraminidase inhibitor taken by inhalation, has been approved by the FDA for treatment of influenza. Oseltamivir phosphate, an oral neuraminidase inhibitor, will probably be approved soon.

Since publication of our recent article on antiviral drugs for influenza, increased levels of resistance to oseltamivir (Tamiflu) have been detected in influenza A H1N1 strains.

The oral polymerase acidic endonuclease inhibitor baloxavir marboxil (Xofluza — Genentech) is now FDAapproved for post-exposure prophylaxis of influenza in patients ≥12 years old. Baloxavir was approved for treatment of acute uncomplicated influenza in patients ≥12 years old in 2018.1 Two neuraminidase inhibitors are FDA-approved for prophylaxis of influenza: oseltamivir (Tamiflu, and generics) in patients ≥1 year old, and zanamivir (Relenza) in patients ≥5 years old.2 Unlike oseltamivir and zanamivir, baloxavir is not FDA-approved for pre-exposure prophylaxis of...

Influenza is generally a self-limited illness, but pneumonia, respiratory failure, and death can occur, especially in persons at increased risk for influenza complications (see Table 1). Updated information on influenza activity and antiviral resistance is available from the CDC at cdc.gov/flu.

Some readers of our article on Antiviral Drugs for Seasonal Influenza have expressed concerns regarding our recommendation for use of the oral neuraminidase inhibitor oseltamivir (Tamiflu) to treat high-risk patients with confirmed or suspected influenza illness, citing the British Medical Journal and The Cochrane Collaboration, which have contended that there is no acceptable evidence that the drug prevents complications or hospitalizations and have questioned the completeness of the results of controlled trials conducted by the manufacturer (Roche).

The FDA has approved peramivir (Rapivab – BioCryst), an IV neuraminidase inhibitor administered as a single dose, for treatment of acute uncomplicated influenza in patients ≥18 years old who have had symptoms for no more than 2 days. Peramivir was available temporarily in the US during the 2009-2010 influenza season under an emergency use authorization for treatment of hospitalized patients. It has been available in some Asian countries since 2010. Peramivir is the third neuraminidase inhibitor to be approved in the US. Oseltamivir (Tamiflu), which is taken orally, and zanamivir...

View the Comparison Chart: Antiviral Drugs for Seasonal Influenza for 2024-2025

The FDA has approved baloxavir marboxil (Xofluza – Shionogi/Genentech), the first polymerase acidic (PA) endonuclease inhibitor, for single-dose, oral treatment of acute uncomplicated influenza in patients ≥12 years old. Baloxavir is the first drug with a new mechanism of action to be approved for treatment of influenza in almost 20 years.

The drugs of choice for treatment of viral infections (other than HIV) and their dosages are listed in Tables 1-6 on the pages that follow. Some of the indications and dosages recommended here have not been approved by the FDA. Vaccines used for the prevention of viral infections are discussed elsewhere.

Healthcare providers are often asked if drugs can be used past their expiration date. Because of legal restrictions and liability concerns, manufacturers do not sanction such use and usually do not comment on the safety or effectiveness of their products beyond the date on the label. Since our last article on this subject, more data have become available.