Generic Name: oseltamivir (os el TAM ih veer)
Brand Names: Tamiflu
Medically reviewed by Sophia Entringer, PharmD Last updated on Apr 15, 2019.
What is oseltamivir?
Oseltamivir 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. Oseltamivir may also be given to prevent influenza in people who may have been exposed but do not yet have symptoms. This medicine will not treat the common cold.
It is dangerous to purchase oseltamivir 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.
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 this medicine, 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 this medicine 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
Oseltamivir 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 this medicine.
You should not use oseltamivir if you are allergic to it.
Do not use oseltamivir to prevent influenza in a child younger than 3 months old. Do not use this medicine to treat influenza in a child younger than 2 weeks old unless instructed by your doctor.
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 oseltamivir 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 oseltamivir?
Take oseltamivir 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.
Take the oseltamivir 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).
Oseltamivir may be taken with food if it upsets your stomach.
To treat flu symptoms: Take oseltamivir 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.
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 oseltamivir 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
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 oseltamivir?
Do not use a nasal flu vaccine (FluMist) within 48 hours after taking this medicine. Oseltamivir 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 signs of an allergic reaction to oseltamivir (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 oseltamivir (especially children) have had sudden unusual changes in mood or behavior. It is not certain that this medicine 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:
tremors or shaking;
unusual behavior; or
hallucinations (hearing or seeing things that are not there).
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.
What other drugs will affect oseltamivir?
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.
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use oseltamivir only for the indication prescribed.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
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More about oseltamivir
- Side Effects
- During Pregnancy or Breastfeeding
- Dosage Information
- Patient Tips
- Drug Images
- Drug Interactions
- Pricing & Coupons
- En Español
- 493 Reviews
- Drug class: neuraminidase inhibitors
- FDA Alerts (1)
Other brands: Tamiflu