Oseltamivir Phosphate Granules is an antiviral drug, not a fever reducer. Oseltamivir phosphate granules are used clinically for the treatment of influenza A and B in adults, children one year of age and older, and for the prevention of influenza A and B in adults and adolescents 13 years of age and older. When used for influenza treatment, treatment should be initiated on the first or second day of the onset of influenza symptoms, ideally within 36 hours. Common adverse reactions include nausea, vomiting, insomnia and dizziness. Allergic reactions to the skin, as well as hepatitis, elevated liver enzymes, laryngeal edema, and bronchospasm have been reported in a very small number of cases. Patients experiencing similar reactions should discontinue the medication and go to the hospital.