Uses
What is oseltamivir used for?
Oseltamivir is commonly used for the treatment of the flu (influenza A and B), but only within the first two days of having flu symptoms. Oseltamivir is also used for the prevention of flu. The flu, short for influenza, is caused by influenza viruses that infect parts of the body, leading to symptoms such as fever, cough, sore throat, body aches, and fatigue.
Oseltamivir may also be used for other conditions as determined by your healthcare provider.
How does oseltamivir work (mechanism of action)?
Oseltamivir blocks the creation of new virus particles, which helps your body’s immune system fight the infection.
How is oseltamivir supplied (dosage forms)?
Oseltamivir is available as Tamiflu and generic oseltamivir in the following dosage forms that are taken by mouth.
- 30 mg oral capsules
- 45 mg oral capsules
- 75 mg oral capsules
- 6 mg/mL powder for oral suspension
How should I store oseltamivir?
Oral Capsules. Oseltamivir capsules should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place.
Oral Liquid. Oseltamivir oral liquid should be stored under refrigeration for up to 17 days at 36 F to 46 F (2 C to 8 C). Do not freeze. Oseltamivir oral liquid may also be stored for 10 days at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it.
Side Effects
What are the most common side effects of oseltamivir?
The most common side effects of oseltamivir are listed below. Tell your healthcare provider if you have any of these side effects that bother you.
- Nausea
- Vomiting
- Headache
- Pain
There may be other side effects of oseltamivir that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.
What are the serious side effects of oseltamivir?
While less common, the most serious side effects of oseltamivir are described below, along with what to do if they happen.
Severe Allergic Reactions. Oseltamivir may cause allergic reactions, which can be serious. Stop using oseltamivir and get help right away if you have any of the following symptoms of a serious allergic reaction.
- Breathing problems or wheezing
- Racing heart
- Fever or general ill feeling
- Swollen lymph nodes
- Swelling of the face, lips, mouth, tongue, or throat
- Trouble swallowing or throat tightness
- Itching, skin rash, or pale red bumps on the skin called hives
- Nausea or vomiting
- Dizziness, feeling lightheaded, or fainting
- Stomach cramps
- Joint pain
Severe Skin Reactions. Oseltamivir can cause severe skin reactions called erythema multiforme, Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) that can lead to death if not treated. If you develop a rash, stop oseltamivir and call your healthcare provider right away. Get emergency help right away if you have any of the following symptoms of a severe skin reaction.
- Painful red or purple skin that looks burned and peels off
- Flat red rash or blisters on your skin, mouth, nose, and genitals
- Red, painful, watery eyes
- Flat, round red patches that have dark circles with purple-grey centers
- Sudden, red patches and blisters on the face, palms of hands, and soles of feet
Change in Behavior. Children and people with the flu may experience nervous system problems and abnormal behavior that could be fatal. If you or your child exhibit confusion, speech issues, shaky movements, seizures, or hearing or seeing things that are not real while taking oseltamivir, tell your healthcare provider right away.
Warnings & Precautions
Who should not use oseltamivir?
Allergies to Ingredients. People who are allergic to any of the following should not use oseltamivir.
- Oseltamivir
- Tamiflu
- Any of the ingredients in the specific product dispensed
Your pharmacist can tell you all of the ingredients in the specific oseltamivir products they stock.
What should I know about oseltamivir before using it?
Do not take oseltamivir unless it has been prescribed to you by a healthcare provider. Take it as prescribed.
Do not share oseltamivir with other people, even if they have the same condition as you. It may harm them.
Keep oseltamivir out of the reach of children.
There is less chance of stomach upset if you take oseltamivir with food.
What should I tell my healthcare provider before using oseltamivir?
Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if oseltamivir is right for you.
In particular, make sure that you discuss any of the following.
Current and Past Health Conditions. Tell your healthcare provider if you have any of the following.
- Problems swallowing
- Kidney problems
Fructose Intolerance. Patients with hereditary fructose intolerance should be cautious with fructose intake. One 75 mg dose of the oseltamivir oral liquid contains 2 grams of sorbitol. This amount exceeds the daily limit of sorbitol for people with hereditary fructose intolerance and can cause an upset stomach and diarrhea.
Other Medicines and Supplements. Oseltamivir may interact with other medicines and supplements. Before using oseltamivir, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.
Pregnancy. It is not known if or how oseltamivir could affect pregnancy or harm an unborn baby. Tell your healthcare provider if you are or plan to become pregnant. Your healthcare provider will advise you if you should take oseltamivir while you are pregnant or trying to get pregnant.
Breastfeeding. Oseltamivir passes into breast milk. Tell your healthcare provider if you are breastfeeding or plan to breastfeed. Your healthcare provider will advise you if you should take oseltamivir while breastfeeding.
Interactions
Does oseltamivir interact with foods or drinks?
There are no known interactions between oseltamivir and foods or drinks.
It is unknown if drinking alcohol will affect oseltamivir.
Does oseltamivir interact with other medicines (drug interactions)?
Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.
In particular, make sure that you discuss if you are going to receive the live flu vaccine before taking oseltamivir.
This may not be a complete list of medicines that can interact with oseltamivir. Always check with your healthcare provider.
Overdose/Missed Dose
What should I do if I accidentally use too much oseltamivir?
If you or someone else has used too much oseltamivir, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.
What should I do if I miss a dose of oseltamivir?
If you miss a dose, take it as soon as you remember. If your next dose is within two hours or less, skip the missed dose and only take the next dose. Do not take double or extra doses.
Are you currently using Oseltamivir (Tamiflu)?
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