What is oseltamivir, and how does it work (mechanism of action)?

Oseltamivir is an oral medication used for treating and preventing the “flu.” It is similar to zanamivir (Relenza). Oseltamivir suppresses and decreases the spread of influenza A and B viruses, the viruses responsible for the flu. It does this by blocking the action of neuraminidase, an enzyme produced by the viruses that enables the viruses to spread from infected cells to healthy cells. By preventing the spread of virus from cell to cell, the symptoms and duration of influenza infection are reduced. On average, oseltamivir reduces the duration of symptoms by one and a half days if treatment is started within forty-eight hours of the beginning of symptoms.

The FDA approved oseltamivir in October 1999.

What brand names are available for oseltamivir?


Is oseltamivir available as a generic drug?


Do I need a prescription for oseltamivir?


What are the side effects of oseltamivir?

The most frequent side effects of oseltamivir are:

Administering oseltamivir after meals helps reduce nausea.

Other reported adverse events include:

What is the dosage for oseltamivir?

Oseltamivir is administered orally. For the best results, treatment should begin within 2 days of symptom onset or exposure.

  • The recommended dose for treating adults with flu is 75 mg twice daily for five days.
  • Children are treated with 30-75 mg twice daily for five days. Dosing depends on body weight.
  • The adult dose for prevention of flu is 75 mg daily for 10 days. Children receive 30-75 mg once daily for 10 days.

Which drugs or supplements interact with oseltamivir?

Oseltamivir potentially may interfere with the action of the live attenuated flu vaccine that is given by injection because oseltamivir prevents viral replication. Therefore, live attenuated flu vaccine should not be administered within two weeks before or 48 hours after administration of oseltamivir.

Is oseltamivir safe to take if I’m pregnant or breastfeeding?

The Centers for Disease Control (CDC) recommends use of oseltamivir for treating flu in pregnant women.

The CDC recommends that women with flu who have recently given birth may be treated with oseltamivir. Oseltamivir is approved for use in children one year old and older, and available evidence suggests that the risk of adverse events is low when oseltamivir is used in children less than 1 year old.

What else should I know about oseltamivir?

What preparations of oseltamivir are available?

Capsules: 30, 45, and 75 mg. Suspension: 6 mg/ml and 12 mg/ml

How should I keep oseltamivir stored?

Oseltamivir should be stored at room temperature, 15 C to 30 C (59 F to 86 F).

Medically Reviewed on 3/13/2019


Medically reviewed by John P. Cunha, DO, FACOEP; Board Certified Emergency Medicine


FDA Prescribing Information.