Oseltamivir, known generically as oseltamivir phosphate capsules, is usually given for 7 days between prevention and 5 days between treatments. Oseltamivir phosphate capsules are a medication that prevents and treats influenza A and B viruses. Oseltamivir phosphate for influenza prophylaxis should be used for at least 7 days after close contact with a person with influenza, and should also be started within 2 days in close contacts, with a therapeutic dosage of 5 days shared among adults. Oseltamivir phosphate is contraindicated in persons with known hypersensitivity to any of the components of this product. The safety and effectiveness of oseltamivir phosphate in children under 1 year of age have not been established. The duration and dosage of oseltamivir phosphate capsules vary for each person’s therapeutic purpose, and the medication should be used and discontinued as directed by your doctor.