Oseltamivir (patient information)

Why is this medication prescribed

Oseltamivir is used to treat some types of influenza infection ('flu') in adults and children (older than 1 year of age) who have had symptoms of the flu for no longer than 2 days. This medication is also used to prevent some types of flu in adults and children (older than 1 year of age) when they have spent time with someone who has the flu or when there is a flu outbreak. Oseltamivir is in a class of medications called neuraminidase inhibitors. It works by stopping the spread of the flu virus in the body. Oseltamivir helps shorten the time you have flu symptoms such as a stuffy or runny nose, sore throat, cough, muscle or joint aches, tiredness, headache, fever, and chills. Oseltamivir will not prevent bacterial infections which may occur as a complication of the flu.

How should this medicine be used

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 twice daily (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 you can lessen the chance of getting an upset stomach by taking oseltamivir 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.

To prepare doses of oseltamivir liquid:

• Shake the liquid well (for about 5 seconds) before each use to mix the medication evenly.
• Open the bottle by pushing down on the cap and turning the cap at the same time.
• Push the plunger of the measuring device completely down to the tip.
• Insert the tip of the measuring device firmly into the opening on the top of the bottle.
• Turn the bottle (with the measuring device attached) upside down.
• Pull back on the plunger slowly until the amount of liquid 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.
• Turn the bottle (with the measuring device attached) right side up and slowly remove the measuring device.
• Take oseltamivir directly into your mouth from the measuring device; do not mix with any other liquids.
• Replace the cap on the bottle and close tightly.
• 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 your dose of oseltamivir solution if you do not have the measuring device.

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.

Other uses for this medicine

Oseltamivir may be used to treat and prevent infections from avian (bird) influenza (a virus that usually infects birds but can also cause serious illness in humans).

What special precautions should I follow

Before taking oseltamivir

• tell your doctor and pharmacist if you are allergic to oseltamivir or any other medications.
• tell your doctor what prescription and nonprescription medications, vitamins, nutritional supplements and herbal products you are taking or plan to take. Be sure to mention any of the following: medications that affect the immune system such as azathioprine (Imuran); cyclosporine (Neoral, Sandimmune); cancer chemotherapy medications; methotrexate (Rheumatrex); sirolimus (Rapamune); oral steroids such as dexamethasone (Decadron, Dexone), methylprednisolone (Medrol), and prednisone (Deltasone); or tacrolimus (Prograf). Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
• tell your doctor if you have ever taken oseltamivir to treat or prevent the flu.
• tell your doctor if you have any disease or condition that affects your immune system such as human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS) or if you have heart, liver, lung, or kidney disease.
• tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking oseltamivir, call your doctor.
• you should know that some people who took oseltamivir to treat flu became confused, behaved strangely, and in some cases harmed themselves. These symptoms were most common in children but were also experienced by adults. If your child is taking oseltamivir, you should watch his or her behavior very carefully and call the doctor right away if he or she becomes confused or behaves abnormally. If you are taking oseltamivir, you, your family, or your caregiver should call the doctor right away if you become confused, behave abnormally, or think about harming yourself. Be sure that your family or caregiver knows which symptoms may be serious so they can call the doctor if you are unable to seek treatment on your own.
• ask your doctor if you should receive a flu vaccination each year. Oseltamivir does not take the place of a yearly flu vaccine. If you received or plan to receive the intranasal flu vaccine (FluMist; flu vaccine that is sprayed into the nose), you should tell your doctor before taking oseltamivir. Oseltamivir may interfere with the activity of the intranasal flu vaccine if it is taken up to 2 weeks after or up to 48 hours before the vaccine is administered.

What should I do if I forget a dose

If you forget to take a dose, take it as soon as you remember it. If it is no longer than 2 hours before your next scheduled dose, skip the missed dose and continue your regular dosing schedule. If you miss several doses, call your doctor for directions. Do not take a double dose to make up for a missed one.

Side effects

Mild side effects

Oseltamivir may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• nausea
• vomiting
• stomach pain
• diarrhea
• headache
• difficulty falling asleep or staying asleep
• cough
• dizziness

Severe side effects

Some side effects can be serious. If you experience any of these symptoms or those mentioned in the SPECIAL PRECAUTIONS section, call your doctor immediately:

• rash, hives, or blisters on the skin
• itching
• swelling of the face or tongue
• difficulty breathing or swallowing
• hoarseness

What storage conditions are needed for this medicine

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). Keep the liquid in the refrigerator. Do not freeze oseltamivir liquid. Throw away any unused liquid medication after 10 days. Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.

In case of emergency/overdose

In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.

Symptoms of overdose may include:

• nausea
• vomiting

What other information should I know

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.

Brand names

• Tamiflu®