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.

Oseltamivir comes as a capsule and a suspension (liquid) to take by mouth. When oseltamivir is used to treat flu symptoms, it is usually taken two times a day (morning and evening) for 5 days. When oseltamivir is used to prevent flu, it is usually taken once a day for at least 10 days, or for up to 6 weeks during a community flu outbreak. Oseltamivir may be taken with or without food, but is less likely to cause upset stomach if it is taken with food or milk. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part that you do not understand. Take oseltamivir exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

It is important to know the dose of medication your doctor has prescribed and to use a measuring device that will measure the dose accurately. If you are taking the medication yourself or giving it to a child older than 1 year of age, you can use the device provided by the manufacturer to measure the dose according to the instructions below. If you are giving the medication to a child under one year of age, you should not use the measuring device provided by the manufacturer because it cannot accurately measure small doses. Instead, use the device provided by your pharmacist. If the commercial suspension is unavailable and your pharmacist prepares a suspension for you, he or she will provide a device to measure your dose. Never use a household teaspoon to measure doses of oseltamivir oral suspension.

If you are giving the commercial suspension to an adult or child over one year of age, follow these steps to measure the dose using the syringe provided:

1. Shake the suspension well (for about 5 seconds) before each use to mix the medication evenly.
2. Open the bottle by pushing down on the cap and turning the cap at the same time.
3. Push the plunger of the measuring device completely down to the tip.
4. Insert the tip of the measuring device firmly into the opening on the top of the bottle.
5. Turn the bottle (with the measuring device attached) upside down.
6. Pull back on the plunger slowly until the amount of suspension prescribed by your doctor fills the measuring device to the appropriate marking. Some larger doses may need to be measured using the measuring device twice. If you are not sure how to correctly measure the dose your doctor has prescribed, ask your doctor or pharmacist.
7. Turn the bottle (with the measuring device attached) right-side up and slowly remove the measuring device.
8. Take oseltamivir directly into your mouth from the measuring device; do not mix with any other liquids.
9. Replace the cap on the bottle and close tightly.
10. Remove the plunger from the rest of the measuring device and rinse both parts under running tap water. Allow the parts to air dry before putting back together for the next use.

Call your doctor or pharmacist to find out how you should measure a dose of oseltamivir suspension if you do not have the measuring device that came with this medication.

If you have difficulty swallowing capsules, your doctor may tell you to open the capsule and mix the contents with a sweetened liquid. To prepare doses of oseltamivir for people who cannot swallow the capsules:

1. Hold the capsule over a small bowl and carefully pull open the capsule and empty all of the powder from the capsule into the bowl. If your doctor has instructed you to take more than one capsule for your dose, then open the correct number of capsules into the bowl.
2. Add a small amount of sweetened liquid, such as regular or sugar-free chocolate syrup, corn syrup, caramel topping, or light brown sugar dissolved in water to the powder.
3. Stir the mixture.
4. Swallow the entire contents of this mixture right away.

Continue to take oseltamivir until you finish the prescription, even if you start to feel better. Do not stop taking oseltamivir without talking to your doctor. If you stop taking oseltamivir too soon or skip doses, your infection may not be fully treated, or you may not be protected from the flu.

If you feel worse or develop new symptoms while taking oseltamivir, or if your flu symptoms do not start to get better, call your doctor.

Ask your pharmacist or doctor for a copy of the manufacturer's information for the patient.

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.

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

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

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.

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.

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

Keep this medication in the container it came in and out of reach of children. Store the capsules at room temperature and away from excess heat and moisture (not in the bathroom). Commercial oseltamivir suspension can be kept at room temperature for up to 10 days or in the refrigerator for up to 17 days. Oseltamivir suspension prepared by a pharmacist can be kept at room temperature for up to 5 days or in the refrigerator for up to 35 days. Do not freeze oseltamivir suspension.

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. http://www.upandaway.org

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website (http://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.

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.

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:

• sudden confusion;

• tremors or shaking;

• unusual behavior; or

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

Common oseltamivir side effects may include:

• nausea, vomiting;

• headache; or

• pain.

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.

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.

Oseltamivir will not stop you from giving the flu to others. You should wash your hands frequently, and avoid practices such as sharing cups and utensils that can spread the virus to others.

Do not let anyone else take your medication. Your prescription is probably not refillable. If you still have symptoms of the flu after you finish taking oseltamivir, call your doctor.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.