Key Takeaways
- The usual Tamiflu dosage for treatment of the flu in adults is 75 mg twice per day for 5 days.
- The typical Tamiflu dosage for the prevention of the flu in adults is 75 mg once per day for at least 10 days.
- The Tamiflu dosage for children depends on the age and body weight of the child and whether the drug is being used for treatment or prevention of the flu.
Tamiflu (oseltamivir) may be prescribed for adults and some children for the prevention or treatment of influenza (flu). It can be used for either influenza A or influenza B. Tamiflu may be prescribed when you’ve been in close physical contact with someone who has the flu. Or it may be prescribed if you’ve had flu symptoms for 48 hours or less.
The active ingredient in Tamiflu is oseltamivir. Tamiflu belongs to a group of drugs called antivirals.
This article describes the dosages of Tamiflu, as well as its strengths and how to take it.
The information below describes Tamiflu dosages that are commonly used or recommended. But be sure to take the dosage your doctor prescribes for you. They’ll determine the best dosage to fit your needs.
Tamiflu forms
Tamiflu comes in two forms that you swallow:
- a capsule
- a liquid suspension (liquid mixture)
Tamiflu strengths
Tamiflu is available in the following strengths:
- oral capsule: 30 milligrams (mg), 45 mg, and 75 mg
- oral liquid suspension: 6 mg per milliliter (mg/mL)
The prescribed Tamiflu dosage may vary depending on the reason it’s being used. Always follow your doctor’s instructions. Notify them if you experience any side effects that may prevent you from taking your medication.
Dosage to treat influenza in adults
The usual dosage for treatment of the flu in adults is 75 mg of Tamiflu taken twice per day for 5 days. If you’ve had flu symptoms for no more than 48 hours, your doctor may prescribe Tamiflu for this use.
Dosage to help prevent influenza in adults
The usual Tamiflu dosage for prevention of the flu in adults is 75 mg once daily for at least 10 days. If you’ve been exposed to someone with the flu in the last 48 hours, your doctor may prescribe Tamiflu as preventive therapy.
Your doctor may also prescribe Tamiflu when there’s been a community outbreak of influenza. A community outbreak of influenza is a spike in the number of people with the infection in your community beyond what health officials expect to see. To prevent the flu during a community outbreak, you’ll likely take 75 mg of Tamiflu once per day for up to 6 weeks. But if you have a weakened immune system, your doctor may recommend that you take Tamiflu for up to 12 weeks.
If you have questions about your dosage of Tamiflu, talk with your doctor or pharmacist.
Tamiflu may be given to some children to either help prevent or treat the flu. Your child’s doctor may prescribe the capsule or liquid suspension.
The table below summarizes the recommended dosages of Tamiflu for children. Dosages depend on the age and body weight of the child and whether Tamiflu is being given for prevention or treatment of influenza. Body weight is shown in kilograms (kg). Dosages are in mg or mg per kg (mg/kg). One kg is about 2.2 pounds (lb).
| Age | Body weight | Dosage for treatment, 5 days | Dosage for prevention, 10 days |
|---|---|---|---|
| 2 weeks to less than 1 year | any weight | 3 mg/kg twice per day | — |
| 1 to 12 years | 15 kg or less | 30 mg twice per day | 30 mg once per day |
| 1 to 12 years | 15.1 to 23 kg | 45 mg twice per day | 45 mg once per day |
| 1 to 12 years | 23.1 to 40 kg | 60 mg twice per day | 60 mg once per day |
| 1 to 12 years | 40.1 kg or more | 75 mg twice per day | 75 mg once per day |
| 13 years and older | any weight | 75 mg twice per day | 75 mg once per day for at least 10 days |
Note: If there’s a community outbreak of the flu, your child will take Tamiflu for up to 6 to 12 weeks to help prevent the flu.
Dosage to treat influenza in children
Doctors prescribe Tamiflu to children ages 2 weeks and older to treat the flu. Children who are prescribed Tamiflu should take it within 2 days of the start of their flu symptoms.
For details on the children’s dosages for this use, see the table above. For more information about Tamiflu’s dosage for children, talk with your child’s doctor or a pharmacist.
Dosage to help prevent influenza in children
For prevention of influenza, children ages 1 year and older may be prescribed Tamiflu within 48 hours of exposure to someone with the flu.
For details on the children’s dosages for this use, see the table above. For more information about Tamiflu’s dosage for children, talk with your child’s doctor or a pharmacist.
Tamiflu is available as an oral capsule or oral liquid suspension.
If your doctor prescribes the capsule, you’ll swallow it whole. Don’t crush or chew the capsule.
If you or your child has trouble swallowing capsules, talk with your doctor or pharmacist about taking the liquid suspension instead. If the liquid suspension isn’t available at your pharmacy, they may be able to show you how to open the capsule and mix its contents with another liquid.
If you’re taking Tamiflu to treat the flu, it’s helpful to take each dose about 12 hours apart. If you’re taking Tamiflu to help prevent the flu, try to take it around the same time every day. Doing so helps keep constant levels of Tamiflu in your body so the drug can work effectively.
Tamiflu can be taken with or without food, but taking it with food may lower the risk of getting an upset stomach.
You can learn more about taking the capsule or liquid suspension in Tamiflu’s prescribing information. You can also talk with your doctor or pharmacist.
How long do you take Tamiflu?
Tamiflu is usually prescribed as a short-term treatment to treat or help prevent the flu.
You’ll typically take Tamiflu for 5 days to treat the flu and for 10 days to help prevent the flu. If there’s been a community outbreak, you may take Tamiflu for up to 12 weeks to help prevent the flu.
If you have more questions about the length of treatment with Tamiflu, talk with your doctor or pharmacist.
The dosage of Tamiflu you’re prescribed may depend on several factors. These include:
- whether it’s being used to treat or help prevent the flu
- your age
- the health of your immune system
- your kidney function
- body weight (for children)
Dosage adjustments
Your doctor may adjust your dosage of Tamiflu if you have kidney disease. Depending on the severity of your kidney disease, your doctor may decrease your dose, your dosing frequency, or both. If you’re receiving hemodialysis or peritoneal dialysis for end stage kidney disease, your doctor will also make certain dosage adjustments.
Also, if you have a weakened immune system, your doctor may recommend that you take Tamiflu for a longer time, especially if you’re taking it to help prevent infection during a community outbreak of influenza.
If you have questions about how kidney disease or a weakened immune system affects your Tamiflu dosage, talk with your doctor to learn more.
Do not take more Tamiflu than your doctor prescribes, as this can lead to harmful effects.
Call your doctor right away if you think you’ve taken too much Tamiflu. You can also call 800-222-1222 to reach America’s Poison Centers or use its online resource. But if you have severe symptoms, immediately call 911 (or your local emergency number) or go to the nearest emergency room.
Below are answers to some commonly asked questions about Tamiflu’s dosage.
What if I miss a dose of Tamiflu?
If you miss a dose of Tamiflu, take it as soon as you remember. But if it’s within 2 hours of your next dose, skip the missed dose and take your next dose at its usual time. Do not take a double dose to make up for a missed dose. If you’re not sure whether you should take a missed dose or skip it, talk with your doctor or pharmacist.
If you need help remembering to take your dose of Tamiflu on time, try using a medication reminder. This can include setting an alarm or downloading a reminder app on your phone.
How long does it take for Tamiflu to start working?
Tamiflu starts to work after your first dose. Studies have shown that Tamiflu decreases the number of days of flu symptoms when taken to treat the flu. When used for prevention, it decreases the chance of developing flu symptoms and the severity of symptoms, especially for those who may have a weakened immune system.
If you have other questions about what to expect from taking Tamiflu, talk with your doctor.
Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.