Skip to Content

Tamiflu

Generic Name: oseltamivir (os el TAM ih veer)
Brand Names: Tamiflu

Medically reviewed on May 8, 2018.

What is Tamiflu?

Tamiflu (oseltamivir) is an antiviral medication that blocks the actions of influenza virus types A and B in your body.

Tamiflu is used to treat influenza in people 2 weeks of age and older who have had flu symptoms for 2 days or less. Oseltamivir may also be given to prevent influenza in people who are at least 1 year old, who may be exposed but do not yet have symptoms. Oseltamivir will not treat the common cold.

It is dangerous to purchase Tamiflu on the Internet or outside the United States. The sale and distribution of medicines outside the U.S. does not comply with safe-use regulations of the Food and Drug Administration (FDA). These medications may contain dangerous ingredients, or may not be distributed by a licensed pharmacy. Samples of "Tamiflu" purchased on the Internet have been found to contain cloxacillin, a type of antibiotic that can have dangerous side effects in people who are allergic to penicillin.

Important Information

Tamiflu is used to treat flu symptoms caused by influenza virus in patients who have had symptoms for less than 2 days. It may also be given to prevent influenza in people who may be exposed but do not yet have symptoms. This medicine will not treat the common cold.

Before taking Tamiflu, tell your doctor if you have received a nasal flu vaccine within the past 2 weeks, or if you have kidney disease, heart disease, lung disease, or any other serious disease or health problem. Also tell your doctor if you have any condition causing swelling or disorder of the brain.

Take Tamiflu for as many days as it has been prescribed for you even if you begin to feel better. Your symptoms may start to improve before the infection is completely treated.

Some people using oseltamivir have had rare side effects of sudden confusion, delirium, hallucinations, unusual behavior, or self-injury. These symptoms have occurred most often in children. It is not known whether this medicine was the exact cause of these symptoms. However, anyone using this medicine should be watched closely for signs of confusion or unusual behavior. Call a doctor at once if you or the child using this medicine has any of these symptoms.

Before taking this medicine

Tamiflu should not be used in place of getting a yearly flu shot. The Centers for Disease Control (CDC) recommends an annual flu shot to help protect you each year from new strains of influenza virus. You can get a flu shot even while using Tamiflu.

You should not use this medicine if you are allergic to oseltamivir.

Do not use Tamiflu to prevent influenza in a child younger than 1 year old. Do not use oseltamivir to treat influenza in a child younger than 2 weeks old.

Tell your doctor if you have ever had:

  • kidney disease (or if you are on dialysis);

  • heart disease or chronic lung disease;

  • a condition causing swelling or disorder of the brain;

  • a weak immune system (caused by disease or by using certain medicine);

  • hereditary fructose intolerance; or

  • if you have used a nasal flu vaccine (FluMist) within the past 2 weeks.

It is not known whether this medicine will harm an unborn baby. However, getting sick with influenza during pregnancy can cause complications leading to birth defects, low birth weight, preterm delivery, or stillbirth. Your doctor will decide whether you should receive oseltamivir if you are pregnant.

The Centers for Disease Control and Prevention (CDC) recommends that pregnant women may receive a yearly flu vaccine to prevent influenza. Oseltamivir is not to be used in place of the yearly flu shot.

It is not known whether Tamiflu passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breast-feeding a baby.

How should I take Tamiflu?

Take Tamiflu exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Start taking Tamiflu as soon as possible after flu symptoms appear, such as fever, chills, muscle aches, sore throat, and runny or stuffy nose.

Take the capsule with a full glass of water.

Shake the oral suspension (liquid) before you measure a dose. Use the dosing syringe provided, or use a medicine dose-measuring device (not a kitchen spoon).

Tamiflu may be taken with food if it upsets your stomach.

To treat flu symptoms: Take Tamiflu every 12 hours for 5 days.

To prevent flu symptoms: Take Tamiflu every 24 hours for 10 days or as prescribed. Follow your doctor's instructions.

Read and carefully follow any Instructions for Use provided with your medicine. Ask your doctor or pharmacist if you do not understand these instructions.

Use this medicine for the full prescribed length of time, even if your symptoms quickly improve. Tell your doctor if your symptoms do not improve, or if they get worse.

Store capsules at room temperature away from moisture and heat.

Store liquid medicine in the refrigerator but do not freeze. Throw away any unused liquid after 17 days.

The liquid may also be stored at cool room temperature for up to 10 days

Tamiflu Dosing Information.

Usual Adult Dose for Influenza:

75 mg orally twice a day for 5 days

Use: For the treatment of acute, uncomplicated influenza infection in patients symptomatic no more than 48 hours

Usual Adult Dose for Influenza Prophylaxis:

After close contact with an infected individual: 75 mg orally once a day for at least 10 days
During a community outbreak of influenza: 75 mg orally once a day.

Usual Pediatric Dose for Influenza:

2 weeks to less than 1 year: 3 mg/kg orally twice a day

1 to 12 years:
15 kg or less: 30 mg orally twice a day
15.1 through 23 kg: 45 mg orally twice a day
23.1 through 40 kg: 60 mg orally twice a day
40.1 kg or more: 75 mg orally twice a day

13 years or older: 75 mg orally twice a day

Duration of therapy: 5 days.

Usual Pediatric Dose for Influenza Prophylaxis:

1 to 12 years:
15 kg or less: 30 mg orally once a day
15.1 through 23 kg: 45 mg orally once a day
23.1 through 40 kg: 60 mg orally once a day
40.1 kg or more: 75 mg orally once a day

13 years or older: 75 mg orally once a day

Duration of therapy:
-After close contact with an infected individual: 10 days
-During a community outbreak of influenza: May be continued for up to 6 weeks.

See also: Dosage Information (in more detail)

What happens if I miss a dose?

Use the medicine as soon as you can, but skip the missed dose if your next dose is due in less than 2 hours. Do not use two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking Tamiflu?

Do not use a nasal flu vaccine (FluMist) within 48 hours after taking Tamiflu. Oseltamivir may interfere with the drug action of FluMist, making the vaccine less effective. Follow your doctor's instructions.

Tamiflu side effects

Get emergency medical help if you have signs of an allergic reaction to Tamiflu (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Some people using Tamiflu (especially children) have had sudden unusual changes in mood or behavior. It is not certain that oseltamivir is the exact cause of these symptoms. Even without using oseltamivir, anyone with influenza can have neurologic or behavioral symptoms. Call your doctor right away if the person using this medicine has:

  • sudden confusion;

  • tremors or shaking;

  • unusual behavior; or

  • hallucinations (hearing or seeing things that are not there).

Common Tamiflu side effects may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

See also: Side effects (in more detail)

What other drugs will affect Tamiflu?

Other drugs may interact with oseltamivir, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Tamiflu only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Hide