Taking Tamiflu to Treat the Flu

Treatment is beneficial if started within 48 hours

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Tamiflu (oseltamivir phosphate) is a prescription antiviral medication used to treat influenza (flu). It has been shown to shorten the duration of the flu if taken as soon as symptoms appear.

This article explains when you might need to take Tamiflu and how to take it safely. It reviews possible risks and side effects of the medication.

Boxes of Tamiflu
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Who Can Take It

Tamiflu is approved for use in adults as well as children aged 2 weeks and older. It should not be used in people allergic to oseltamivir phosphate or any other ingredients in Tamiflu.

Because of the risks of flu complications in pregnant people, Tamiflu is recommended to reduce the severity of the illness. Those who are pregnant should begin treatment with Tamiflu as soon as possible when they start having flu symptoms.

Consult your healthcare provider if you have kidney disease, heart disease, respiratory disease, or any other serious health condition.​

When to Take Tamiflu

You may take Tamiflu to treat the flu. To be most effective, it should be started within 48 hours of the onset of your flu symptoms.

in some cases, Tamiflu may be prescribed to prevent the flu. For instance, if someone in your family has the flu, your healthcare provider may prescribe you Tamiflu to help keep you from getting sick. It is most often used in this way for people who are at high risk for complications from the flu or if someone in your house is unable to have a flu shot.

Tamiflu is also sometimes used to protect people from influenza when there are severe outbreaks in communities.


Tamiflu is a prescription medicine so you can only get it after seeing a healthcare provider. It is not available over the counter without a prescription.

If taken to treat the flu, Tamiflu is usually taken twice daily for five days. There is a liquid formula available for young children and people who aren't able to swallow pills. The amount of liquid solution will vary based on weight.

The FDA endorses the following Tamiflu doses for adults and children:

  • Adults and children 13 years and over: 75 milligrams (mg) twice daily for five days
  • Children 12 months to 12 years: Between 30-75 mg, depending on weight, twice daily for five days 
  • Children 2 weeks to 12 months: 3 mg per kilogram (kg) of weight, twice daily for five days

People with kidney impairment may need to reduce the dose to 75 mg once daily for five days.

If used to prevent the flu when someone in your home has it, Tamiflu is usually taken once a day for 10 days. Tamiflu may be taken for up to six weeks in the case of an outbreak of influenza in the community.

Be sure to complete the entire course of treatment even if you feel better.

Side Effects

Tamiflu may cause mild to moderate nausea and vomiting. Taking the medication with food or milk may decrease these symptoms. Less common side effects include bronchitis, difficulty sleeping, and dizziness.

If you have an allergic reaction to Tamiflu, including a severe rash, stop taking it immediately and contact your healthcare provider or seek medical attention right away.


For some people, the flu is a minor inconvenience, but it has the potential to cause serious complications for many others. Tamiflu is a safe and effective way to help prevent severe symptoms and reduce how long you'll suffer from the virus.

A healthcare provider must diagnose and prescribe the medication, which is usually taken twice a day for five days. Guidelines for pregnant people, children, and infants vary.

A Word From Verywell

Tamiflu is the most popular antiviral medication prescribed in the United States to treat and prevent the flu, but it is not the only option. It can cause unpleasant side effects and may be expensive depending on your insurance coverage.

If you aren't sure if Tamiflu is right for you, discuss the pros and cons with your healthcare provider to make an informed choice.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Center for Disease Control and Prevention. Antiviral Drugs Approved for Use in Children.

  2. Centers for Disease Control and Prevention. Influenza (Flu): Pregnancy.

  3. Mclean HQ, Belongia EA, Kieke BA, Meece JK, Fry AM. Impact of late oseltamivir treatment on influenza symptoms in the outpatient setting: results of a randomized trial. Open Forum Infect Dis. 2015;2(3):ofv100. doi:10.1093/ofid/ofv100

  4. U.S. Food and Drug Administration. Tamiflu (oseltamivir phosphate).

By Kristina Duda, RN
Kristina Duda, BSN, RN, CPN, has been working in healthcare since 2002. She specializes in pediatrics and disease and infection prevention.