Antiviral Flu Doctors can give you Flu Medicines like Oseltamivir (Tamiflu) and Zamivir to quickly treat flu symptoms and make the illness less severe and last shorter. Take the drug within 24 hours of the start of any signs for the best results. Herbal Medicine and Antiviral drugs can be bought in a variety of forms, such as liquid, pills, powder, inhaled powder, and intravenous solutions. But because of the risk of Reye's syndrome, these drugs shouldn't be given to kids younger than sixteen.