How long does it take for Tamiflu to work?
Medically reviewed by Sally Chao, MD. Last updated on Feb 2, 2021.
Tamiflu is rapidly absorbed in the stomach, which means that after taking the first dose, the drug starts working quickly to attack the flu virus and prevent it from multiplying. Most people recover from the flu's major symptoms within 3 to 7 days, but if you take Tamiflu (oseltamivir phosphate), it may shorten recovery time by 1 to 2 days.
Tamiflu is the brand name for the drug oseltamivir phosphate. It also comes in a generic version. It is not available over-the-counter and requires a prescription.
Most adults will be prescribed 75 mg of Tamiflu twice a day for five days to treat the flu. Patients with more complicated cases may need to take it for longer.
Still, for Tamiflu to be most effective, the first dose needs to be taken within 48 hours (2 days) after symptoms begin, and the full course of treatment should be completed.
When treatment is initiated within two days of symptoms, it is easier for the drug to prevent the virus from multiplying and taking hold in the body. People at higher risk of developing severe illness or complications from the flu may be advised to take Tamiflu even if those first two days have passed, as the drug may still benefit this patient group.
When taken early and properly, Tamiflu reduces the duration of the flu by 1 to 2 days and curbs the severity of symptoms. It also lowers the risk of serious illness, hospitalization and complications, like bronchitis or pneumonia, which is why it is most commonly given to hospitalized patients or people at higher risk of flu complications.
Taking Tamiflu does not mean you are no longer contagious. Regardless of whether you take Tamiflu, the Centers for Disease Control and Prevention recommends staying at home until you are free of a fever for at least 24 hours without the help of a fever-reducing medicine.
- U.S. Centers for Disease Control and Prevention. Clinical Signs and Symptoms of Influenza. August 31, 2020. Available at: https://www.cdc.gov/flu/professionals/acip/clinical.htm. [Accessed November 11, 2020].
- U.S. Centers for Disease Control and Prevention. Flu Treatment. August 31, 2020. Available at: https://www.cdc.gov/flu/treatment/index.html. [Accessed November 11, 2020].
- U.S. Food and Drug Administration. Tamiflu. Available at: https://www.fda.gov/media/77829/download. [Accessed November 11, 2020].
- U.S. National Library of Medicine. Oseltamivir. January 15, 2018. Available at: https://medlineplus.gov/druginfo/meds/a699040.html. [Accessed November 11, 2020].
- U.S. Centers for Disease Control and Prevention. What You Should Know About Flu Antiviral Drugs. September 3, 2020. Available at: https://www.cdc.gov/flu/treatment/whatyoushould.htm. [Accessed November 11, 2020].
- U.S. Centers for Disease Control and Prevention. Recommended Dosage and Duration of Influenza Antiviral Medications for Treatment or Chemoprophylaxis. January 2015. Available at: https://www.cdc.gov/flu/pdf/professionals/antivirals/antiviral-dosage-duration.pdf. [Accessed November 11, 2020].
- U.S. Centers for Disease Control and Prevention. Influenza (flu): Preventive Steps. September 25, 2020. Available at: https://www.cdc.gov/flu/prevent/prevention.htm#:~:text=For%20flu%2C%20CDC%20recommends%20that,use%20a%20fever%2Dreducing%20medicine. [Accessed November 12, 2020].
- Dobson J, Whitley R, Pockock S, et al. Oseltamivir treatment for influenza in adults: a meta-analysis of randomised controlled trials. The Lancet. 2015 Jan 29;385(9979):1729-1737. https://doi.org/10.1016/S0140-6736(14)62449-1.
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