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Oseltamivir  (Systemic)

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DescriptionReturn to top

Oseltamivir ( Oh–sel–TAM–i–veer) belongs to the family of medicines called antivirals, which are used to treat infections caused by viruses. Oseltamivir is used in the treatment of the infection caused by the flu virus (influenza A and influenza B). Oseltamivir may reduce flu symptoms (weakness, headache, fever, cough, and sore throat) by 1 day. Oseltamivir is also used to prevent influenza infection if you have come into close contact with someone who has the flu.

If you receive the flu vaccine every year, continue to do so. Oseltamivir is not a substitute for your yearly flu shot.

Oseltamivir is available only with your doctor's prescription in the following dosage form:

Before Using This MedicineReturn to top

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For oseltamivir, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to oseltamivir. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Oseltamivir has not been studied in pregnant women. However, studies in animals have shown that oseltamivir causes problems. Before taking this medicine, make sure your doctor knows if you are pregnant or if you may become pregnant.

Breast-feeding—It is not known whether oseltamivir passes into human breast milk. Although most medicines pass into breast milk in small amounts, many of them may be used safely while breast-feeding. Mothers who are using this medicine and who wish to breast-feed should discuss this with their doctor.

Children—This medicine has not been tested in children younger than 1 year of age.

Older adults—This medicine has been tested in older adults and has not been shown to cause different side effects or problems in older adults than it does in younger adults.

Other medicines— Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking oseltamivir it is especially important that your doctor and pharmacist know if you are taking any of the following:

Other medical problems—The presence of other medical problems may affect the use of oseltamivir. Make sure to tell your doctor if you have any other medical problems, especially:

Proper Use of This MedicineReturn to top

Talk to your doctor about the possibility of getting a flu shot if you have not had one yet. Patient information about oseltamivir is available. Read this information carefully.

For patients taking oseltamivir for treatment of the flu: This medicine works best if taken within 2 days of having flu symptoms (weakness, headache, fever, cough, and sore throat). Oseltamivir capsules may be taken with meals or on an empty stomach. Taking oseltamivir with food may lessen the possibility of stomach upset. This medicine should be taken for 5 days. Continue taking this medicine for the full time of treatment even if you begin to feel better after a few days. This will help to clear up your infection completely. If you stop taking this medicine too soon, your symptoms may return.

For patients taking oseltamivir for prevention of the flu after exposure: The medicine should be taken within 2 days of being exposed to the flu. Oseltamivir capsules may be taken with meals or on an empty stomach. Taking oseltamivir with food may lessen the possibility of stomach upset. This medicine should be taken for at least 10 days.

For patients taking the oral suspension form of this medicine:


The dose of oseltamivir will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of oseltamivir. If your dose is different, do not change it unless your doctor tells you to do so.

Missed dose—

This medicine works best when there is a constant amount in the body. To help keep the amount constant, do not miss any doses. If you miss a dose, take as soon as possible, except if it is near the next dose (within 2 hours). Then go back to your regular dosing schedule. Do not double doses. If you have missed several doses, inform your doctor and follow the advice given to you.


To store this medicine:

Precautions While Using This MedicineReturn to top

If your symptoms do not improve after you finish taking the medicine, or if they become worse, check with your doctor.

Side Effects of This MedicineReturn to top

Side Effects of This Medicine

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Stop using this medicine and get emergency help immediately if any of the following side effects occur:

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.

Brand NamesReturn to top

In the U.S.—

  • Tamiflu

In Canada—

  • Tamiflu

CategoryReturn to top

Developed: 01/13/2000
Revised: 01/12/2006

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