oseltamivir
Tamiflu (oseltamivir) works well to treat the flu, but you have to take your first dose within 48 hours of the start of your flu symptoms. It can also help prevent the flu if you've recently been in close contact with someone who has the flu. Kids as young as 2 weeks old can take Tamiflu (oseltamivir), but keep in mind that the pediatric dosing is different than adult dosing. It's only available with a prescription (not available over the counter), so don't wait to see your provider if you start feeling sick. This medication comes as a brand or generic capsule or fruit-flavored liquid. Tamiflu (oseltamivir) can cause side effects like nausea and vomiting.
What is Tamiflu (oseltamivir)?
What is Tamiflu (oseltamivir) used for?
Flu treatment (flu types A and B) in people 2 weeks of age and older
Flu prevention (flu types A and B) in people 1 year of age and older
How Tamiflu (oseltamivir) works
Tamiflu (oseltamivir) is an antiviral medication. More specifically, it's a neuraminidase inhibitor (NAI). Neuraminidase is a protein that's found on the surface of the influenza (flu) virus. It plays a role in helping the virus spread inside someone who's infected. By blocking this protein, Tamiflu (oseltamivir) prevents the flu virus from releasing copies of itself throughout your body and making you feel sicker.
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What are the side effects of Tamiflu (oseltamivir)?
Common Side Effects
- Nausea (10%)
- Vomiting (8%)
- Headache (17%)
- Nausea (8%)
Other Side Effects
- General pain
Serious Side Effects
- Allergic reaction: trouble breathing; swelling of your face, eyes, lips, tongue, or throat
- Serious skin reactions (Stevens-Johnson syndrome): skin rash, hives, blistering or peeling skin
Source: DailyMed
More on Tamiflu (oseltamivir) side effects
The following side effects have also been reported
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.
Check with your doctor immediately if any of the following side effects occur:
Rare
Abdominal or stomach cramps or tenderness
arm, back, or jaw pain
chest pain or discomfort
diarrhea, watery and severe, which may also be bloody
facial swelling
fast or irregular heartbeat
hoarseness
increased thirst
shortness of breath
unusual weight loss
Incidence not known
Blistering, peeling, or loosening of the skin
convulsions (seizures)
dark urine
difficulty with swallowing
fainting
fast, slow, or irregular heartbeat
hives or welts
itching, puffiness, or swelling of the eyelids or around the eyes, face, lips, or tongue
joint or muscle pain
light-colored stools
loss of bladder control
loss of consciousness
muscle spasm or jerking of all extremities
red skin lesions, often with a purple center
red, irritated eyes
skin rash or itching over the entire body
sores, ulcers, or white spots in the mouth or on the lips
sweating
upper right abdominal or stomach pain
yellow eyes and skin
Some 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. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
Less common
Abdominal or stomach pain
bloody nose or unexplained nosebleeds (occurs mainly in children)
burning, dry, or itching eyes (mainly in children)
dizziness
ear disorder (occurs mainly in children)
excessive tearing of the eyes (mainly in children)
redness, pain, or swelling of the eye or eyelid (mainly in children)
trouble with sleeping
Incidence not known
blurred vision
cracked, dry, or scaly skin
flushed, dry skin
mood or mental changes
skin rash that is encrusted, scaly, and oozing
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Pros and cons of Tamiflu (oseltamivir)
Pros
Helps you feel better from the flu about 1 to 2 days sooner than if you didn't take anything
Can also help prevent you from getting the flu
Can be used in children as young as 2 weeks of age and pregnant women
Lower-cost generic version available
Cons
Not a replacement for the annual flu shot
Requires a prescription from your healthcare provider
Only works if you take it within 2 days (48 hours) from when you first felt flu symptoms to treat (or when you were first in contact with someone who has the flu to prevent)
Pharmacist tips for Tamiflu (oseltamivir)
For flu treatment: Make sure you start taking Tamiflu (oseltamivir) as soon as possible after you start having flu symptoms, within 48 hours of the start of symptoms.
For flu prevention: Be sure to start taking Tamiflu (oseltamivir) as soon as possible after you've been exposed to the flu virus.
You can take Tamiflu (oseltamivir) with or without food. Nausea is a common side effect, so if it happens to you, taking Tamiflu (oseltamivir) with food can help lessen it.
If you miss a dose of Tamiflu (oseltamivir), take the missed dose as soon as possible. But if your next dose is in less than 2 hours, you should skip the missed dose. Never double up on doses or take extra.
If you have trouble swallowing, ask your provider about your options (refer to the bottom of the Tips). You can either open the Tamiflu (oseltamivir) capsule and make a solution from the medication or switch to the liquid version of Tamiflu (oseltamivir).
Be sure to take Tamiflu (oseltamivir) for the entire length of time your healthcare provider has prescribed it for you, even if you start feeling well. Don't stop it early unless your provider has told you this is okay. This helps makes sure the flu virus is totally gone.
Although alcohol doesn't interact with Tamiflu (oseltamivir), it can worsen flu symptoms or medication side effects. For this reason, try to avoid drinking alcohol while taking this medication.
Tamiflu (oseltamivir) doesn't replace the annual flu shot. Tamiflu (oseltamivir) can help you feel better sooner. But the flu can still be dangerous, especially to children under 5, adults over 65, and people with chronic health conditions. The best thing you can do to protect yourself is to get your flu shot every year by the end of October.
For the Tamiflu (oseltamivir) capsule:
If it's difficult to swallow the capsule, you can open it and mix the contents with sweetened syrups, such as chocolate syrup, corn syrup, caramel topping, or light brown sugar that's dissolved in water.
For the liquid version of Tamiflu (oseltamivir)
Be sure to shake the bottle very well before taking the medication. Use a medication dosing syringe or medication spoon to measure out the right amount of Tamiflu (oseltamivir) for your dose.
If you store Tamiflu (oseltamivir) in your refrigerator, it will be good for up to 17 days. Storing liquid Tamiflu (oseltamivir) in the fridge can help improve its taste. Make sure the medication doesn't freeze, though.
If you keep the medication at room temperature, it will be good for up to 10 days.
Frequently asked questions about Tamiflu (oseltamivir)
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What are the risks and warnings for Tamiflu (oseltamivir)?
Tamiflu (oseltamivir) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Serious skin reactions and allergic reactions
Risk factors: Previous severe allergic reaction to Tamiflu (oseltamivir)
In some rare cases, people have developed a serious, potentially life-threatening skin reaction called Stevens-Johnson syndrome (SJS) after starting Tamiflu (oseltamivir). This is a type of allergic rash that's painful and creates blisters all over the body. It's also possible to have an allergic reaction (including anaphylaxis) to Tamiflu (oseltamivir). Get medical attention right away if you notice a new or severe rash; a rash accompanied by a fever, unexplained blisters, or new sores inside your mouth; swelling of the face or lips; or trouble breathing.
Unusual behavior and hallucinations
Risk factors: Children
Some people reported changes to their behavior, including hallucinations, after starting Tamiflu (oseltamivir). In studies, this happened more often in children. The flu is known to potentially cause these same changes in behavior, so experts aren't sure whether these mental health changes are due to Tamiflu (oseltamivir) or the flu virus. When this phenomenon happens, it usually comes on without warning and goes away quickly. But very rarely, changes in behavior can possibly include dangerous or deadly actions that lead to injuries. Call your healthcare provider right away if you have a change in thinking clearly, a change in the way you act, speech problems, shakiness, seizures, or hallucinations.
Reaction with nasal spray flu vaccine
It's possible for Tamiflu (oseltamivir) to affect how well the nasal spray flu vaccine works. This vaccine is also called the live attenuated influenza vaccine (LAIV). The nasal spray flu vaccine might not work as well if you get it while you're currently taking or have recently finished Tamiflu (oseltamivir). Wait 48 hours after finishing Tamiflu (oseltamivir) to get the nasal spray flu vaccine. If you received the vaccine less than 2 weeks before starting Tamiflu (oseltamivir), speak with your healthcare provider to see what you should do.
Risk of bacterial infections
Tamiflu (oseltamivir) is an antiviral and doesn't work for treating illnesses caused by bacteria. Some bacterial infections start with flu-like symptoms or can happen while you're still sick with the flu. Tell your healthcare provider right away if you start to feel sick again, have a new fever or chills, or get worse instead of better, as these could be signs of a new or different infection.
Hereditary fructose intolerance (for the liquid form)
The liquid form of Tamiflu (oseltamivir) has sorbitol (a sugar alcohol) in it. People who have a genetic fructose intolerance might get upset stomach and diarrhea if they take this form of Tamiflu (oseltamivir). As an alternative to the liquid form, the capsules don't contain sorbitol and they can be opened and mixed into a sweetened syrup. It's also possible for certain pharmacies (called compounding pharmacies) to create a personalized Tamiflu (oseltamivir) liquid without sorbitol if the dose of the capsules is too high for you or your child. Make sure your healthcare provider and pharmacist are aware of any fructose intolerance.
Tamiflu (oseltamivir) dosage forms
Typical dosing for Tamiflu (oseltamivir)
Flu treatment
Adults and children 13 years of age and older: The typical dose is 75 mg by mouth twice daily for 5 days.
Children ages 1 to 12 years old: The dose is based on your child's body weight. The typical dose ranges from 30 mg to 75 mg by mouth twice daily for 5 days.
Children ages 2 weeks to 1 year old: The dose is based on your child's body weight. The typical dose is 3 mg/kg of body weight by mouth twice daily for 5 days. Your child's provider will calculate the dose for you.
Flu prevention
Adults and children 13 years of age and older: The typical dose is 75 mg by mouth once daily for at least 10 days but not longer than 6 weeks.
Children ages 1 year to 12 years old: The dose is based on your child's body weight. The typical dose ranges from 30 mg to 75 mg by mouth once daily for at least 10 days but not longer than 6 weeks.
Your dose might differ if you have kidney problems (you might need to take the medication less often).
More on Tamiflu (oseltamivir) dosage forms
Interactions between Tamiflu (oseltamivir) and other drugs
More on Tamiflu (oseltamivir) interactions
Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
How much does Tamiflu (oseltamivir) cost?
What are alternatives to Tamiflu (oseltamivir)?
Flu treatment (flu types A and B) in people 2 weeks of age and older
Flu prevention (flu types A and B) in people 1 year of age and older
Flu treatment for people 5 years and older with flu symptoms for no more than 48 hours
Flu prevention for people 5 years and older who've been in contact with someone who has the flu
Flu treatment (flu types A and B) - age 7 years and older
Flu prevention (flu types A and B) - age 5 years and older
What is the latest news about Tamiflu (oseltamivir)?
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References
Best studies we foundAjanta Pharma USA Inc. (2023). Oseltamivir phosphate for suspension [package insert]. DailyMed.
Alembic Pharmaceuticals Limited. (2023). Oseltamivir capsule [package insert]. DailyMed.
American College of Obstetricians and Gynecologists’ Immunization, Infectious Disease, and Public Health Preparedness Expert Work Group. (2021). Assessment and treatment of pregnant women with suspected or confirmed influenza. The American College of Obstetricians and Gynecologists.
Benton, D. J., et al. (2017). Role of neuraminidase in influenza A(H7N9) virus receptor binding. Journal of Virology.
Centers for Disease Control and Prevention. (2020). Spoons are for soup, milliliters are for medicine.
MedlinePlus. (n.d.). Hereditary fructose intolerance.
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