Oseltamivir (Tamiflu) is an antiviral medication that blocks the actions of influenza virus types A and B in your body.
Oseltamivir is used to treat influenza in people 2 weeks of age and older who have had flu symptoms for 2 days or less. It 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.
Oseltamivir may also be used for purposes not listed in this medication guide.
Important information
Some people using oseltamivir have had rare side effects of sudden confusion, shaking, problems with speech, hallucinations (hearing or seeing things that are not there), or seizure (convulsions). It is not known whether oseltamivir was the exact cause of these symptoms.
Oseltamivir 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 oseltamivir, 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 Oseltamivir 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.
Oseltamivir should not be used in place of getting a yearly flu shot. The Centers for Disease Control recommends an annual flu shot to help protect you each year from new strains of influenza virus.
It is dangerous to purchase oseltamivir on the Internet or from vendors outside of the United States. Medications distributed from Internet sales 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. For more information, contact the U.S. Food and Drug Administration (FDA) or visit www.fda.gov/buyonlineguide.
Before using oseltamivir
Oseltamivir should not be used in place of getting a yearly flu shot. The Centers for Disease Control recommends an annual flu shot to help protect you each year from new strains of influenza virus.
You should not use this medication if you are allergic to oseltamivir.
To make sure oseltamivir is safe for you, tell your doctor if you have:
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kidney disease;
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heart disease or chronic lung disease;
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a condition causing swelling or disorder of the brain;
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weak immune system (caused by disease or by using certain medicine);
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hereditary fructose intolerance; or
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if you have used a nasal flu vaccine (FluMist) within the past 2 weeks.
FDA pregnancy category C. It is not known whether oseltamivir is harmful to an unborn baby. However, not receiving this medication to prevent influenza could be harmful to the baby if the mother becomes infected with a disease that oseltamivir could prevent. Tell your doctor if you are pregnant. Your doctor will decide whether you should receive this medicine.
See also: Pregnancy and breastfeeding warnings (in more detail)
It is not known whether oseltamivir passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breast-feeding a baby.
Do not use this medication to prevent influenza in a child younger than 1 year old. Do not use this medication to treat influenza in a child younger than 2 weeks old.
How should I take oseltamivir?
Take oseltamivir exactly as prescribed by your doctor. Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.
Start taking oseltamivir 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) well just before you measure a dose. Measure the liquid with a special dose-measuring spoon or medicine cup. If you do not have a dose-measuring device, ask your pharmacist for one.
You may open the oseltamivir capsule and sprinkle the medicine into a sweet liquid (corn syrup, chocolate syrup, brown sugar dissolved in water) to make swallowing easier. Swallow the mixture right away without chewing. Do not save for later use. Ask your doctor or pharmacist before using this method to prepare an oseltamivir dose for a child who is younger than 13 years old or weighs less than 88 pounds.
Oseltamivir may be taken with food or milk if it upsets your stomach.
To treat flu symptoms: Take every 12 hours for 5 days.
To prevent flu symptoms: Take oseltamivir every 24 hours for 10 days or as prescribed. Follow your doctor"s instructions.
Use this medication for the entire length of time prescribed by your doctor. Your symptoms may get better before the infection is completely treated. Tell your doctor if your symptoms do not improve, or if they get worse.
Store the capsules at room temperature away from moisture and heat.
Store the liquid 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
What happens if I miss a dose?
Take the missed dose as soon as you remember. Skip the missed dose if your next dose is less than 2 hours away. Do not take extra medicine to make up the missed dose.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.
What should I avoid?
Do not use a nasal flu vaccine (FluMist) within 48 hours after taking oseltamivir. It may interfere with the drug action of FluMist, making the vaccine less effective. Follow your doctor"s instructions.
Oseltamivir side effects
Get emergency medical help if you have any of these signs of an allergic reaction to oseltamivir:
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chest pain or tightness, difficult breathing;
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fever, sore throat, swelling in your face or tongue, burning in your eyes; or
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hives, skin pain, followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.
Some people using oseltamivir have had rare side effects of sudden confusion, shaking, problems with speech, hallucinations (hearing or seeing things that are not there), or seizure (convulsions). These symptoms have occurred most often in children, but it is not known whether oseltamivir was the exact cause. Anyone using this medicine should be watched closely for signs of confusion or unusual behavior, especially a child.
Common oseltamivir 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)
Oseltamivir dosing information
Usual Adult Dose for Influenza:
75 mg orally twice a day for 5 days
Approved indication: Treatment of acute, uncomplicated influenza infection in patients symptomatic no more than 48 hours
Usual Adult Dose for Influenza Prophylaxis:
Following 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
Comments:
-Therapy should begin within 48 hours of exposure.
-Safety and efficacy have been established for up to 6 weeks in immunocompetent patients; duration of protection lasts as long as dosing is continued.
-Safety has been established for up to 12 weeks in immunocompromised patients.
Usual Pediatric Dose for Influenza:
2 weeks to less than 1 year: 3 mg/kg orally twice a day
1 through 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 greater: 75 mg orally twice a day
13 years or older: 75 mg orally twice a day
Duration of therapy: 5 days
Approved indication: Treatment of acute, uncomplicated influenza infection in patients (2 weeks or older) symptomatic no more than 48 hours
(Not approved by FDA)
American Academy of Pediatrics (AAP) recommendations:
Full-term infants less than 2 weeks: 3 mg/kg orally twice a day
Usual Pediatric Dose for Influenza Prophylaxis:
1 through 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 greater: 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
Comments:
-Therapy should begin within 48 hours of exposure.
-The FDA has not approved dosing for patients less than 1 year of age.
(Not approved by FDA)
AAP recommendations for full-term infants:
Less than 3 months: Not recommended unless situation judged critical.
3 months to less than 1 year: 3 mg/kg orally once a day
What other drugs will affect oseltamivir?
Other drugs may interact with oseltamivir, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.
