The Food and Drug Administration (FDA) approved the first generic form of Tamiflu, called oseltamivir phosphate. Like Tamiflu, oseltamivir may treat the symptoms of influenza. Influenza, commonly known as the flu, is a respiratory condition caused by influenza viruses that affect the throat, lungs, and nasal passages. Symptoms of flu may include fever, sore throat, and muscle aches.

In people two weeks of age and older, oseltamivir is approved for the treatment of influenza symptoms within the first forty eight hours. Health experts credit this medication with decreasing the duration of flu symptoms by about fifteen hours when it is taken to treat the flu. Oseltamivir is also approved to help prevent influenza in people one year and older. Side effects of oseltamivir include headache, vomiting, and nausea. The generic medication is available in the same three dosage forms as Tamiflu.