What is Tamiflu: Uses, Warnings & Interactions

Updated May 14, 2025  •  Published Dec 30, 2020

Tamiflu is a prescription brand-name antiviral flu treatment that is taken as a capsule or liquid. Its active ingredient, oseltamivir, inhibits the growth of flu virus in the body, helping to minimize flu symptoms and resolve them more quickly before the infection becomes a serious illness. Tamiflu may cause a few minor problems, like nausea or vomiting, in some people, but it rarely causes severe problems.

Tamiflu overview

BRAND NAMES:

  • Tamiflu

Generic Names:

  • Oseltamivir phosphate

Uses:

  • Treats and prevents influenza infections

Therapeutic Classes:

  • Antiviral, neuraminidase inhibitor

Forms:

  • Capsule, oral suspension (liquid)

How it’s taken:

  • By mouth

What is Tamiflu used for?

Tamiflu treats or prevents influenza infections in adults and children.

What form(s) does Tamiflu come in

  • Capsule

    • 30 mg

    • 45 mg

    • 75 mg

  • Oral suspension

    • 6 mg/mL

What are common Tamiflu doses?

  • For influenza infections: 

    • In adults and children 13 years of age and older: 75 mg capsule or 12.5 mL oral suspension taken twice daily for 5 days

    • In children 2 weeks to 12 years old: Doses are based on body weight and taken twice per day for 5 days

  • For influenza prevention: 

    • In adults and children 13 years of age and older: 75 mg capsule or 12.5 mL oral suspension taken once daily for 10 days to six weeks

    • In children 1–12 years old: Doses are based on body weight and taken once daily for 10 days to six weeks

  • For more detailed information about children’s dosages and other dosage information, see Tamiflu dosage, forms, and strengths here.

Common Tamiflu prescriptions

  • Tamiflu
    10 capsules bottle

  • Tamiflu
    60ml of 6mg/ml bottle

  • Tamiflu
    10 capsules box

  • Tamiflu
    10 capsules disp pack

How to take Tamiflu

  • Tamiflu is taken by mouth in a fixed dose once or twice per day for a fixed period of time.

  • Your healthcare provider will tell you how much medicine to use. Do not use more than directed. 

  • Start taking this medicine as soon as possible after flu symptoms begin or within two days after being exposed to influenza.

  • Tamiflu can be taken with or without food. To prevent stomach upset, take Tamiflu with food.

  • Read the Instructions for Use that come with this medicine.

  • How to take Tamiflu capsules:

    • Swallow the capsule whole. Do not crush or chew it.

    • You may open the capsule and mix the contents with a sweet liquid (such as chocolate syrup, corn syrup, or sugar dissolved in water). Ask a healthcare professional for a demonstration.

    • Store Tamiflu capsules at room temperature.

  • How to take Tamiflu oral suspension:

    • Shake the bottle well before measuring a dose.

    • Measure the liquid medicine with the oral syringe or metered dispenser that came with the medicine. Ask your pharmacist for a measuring device if you do not have one.

    • After taking a dose, rinse the oral dosing dispenser with water.

    • Store the oral suspension in the refrigerator for up to 17 days or at room temperature for up to 10 days.

What to do if you miss a dose of Tamiflu

  • If you miss a dose and your next dose is due in more than two hours:

    • Take the missed dose as soon as you can. 

    • Take the next dose at the normal time.

  • If you miss a dose and your next dose is due within two hours: 

    • Skip the missed dose.

    • Take the next dose at the normal time. 

  • Do not use extra medicine to make up for a missed dose.

Tamiflu contraindications

  • This medicine is not right for everyone. 

  • Do not use it if you have had an allergic reaction to oseltamivir or any of the ingredients in the capsule or oral suspension.

Tamiflu warnings

  • Tell any healthcare provider who treats you that you are using this medicine. 

  • Your healthcare provider may need to regularly check on your progress or monitor the effects of this medicine. Keep all appointments.

  • Tell your healthcare provider if you have:

    • Kidney disease

    • Heart disease

    • Lung disease

    • A weakened immune system

    • Problems swallowing capsules

    • Other medical conditions

  • This medicine may cause the following problems: 

    • Unusual thoughts or behaviors

    • Serious skin reactions

  • Call your healthcare provider if your symptoms do not improve or if they get worse.

  • The liquid form of this medicine contains sorbitol. Tell your healthcare provider if you have hereditary fructose intolerance.

  • Do not take this medicine for any illness other than the flu. It will not work for other infections, such as the common cold or bacterial infections.

  • This medicine is not a substitute for a yearly flu shot.

Tamiflu interactions

  • To avoid potentially hazardous drug interactions, tell the prescribing healthcare provider about all prescription drugs, over-the-counter medicines, and supplements you are using before taking Tamiflu.

  • Tell other healthcare providers you are using this medicine before they prescribe new medications. 

  • A live nasal spray flu vaccine may not work if Tamiflu is started two weeks after the vaccine or two days before the vaccine. An inactivated flu shot vaccine will still work in people taking Tamiflu.

  • Otherwise, oseltamivir’s prescribing information lists no drug-drug interactions for doctors to be concerned about.

Tamiflu side effects

Serious side effects

Talk to a healthcare provider if you notice any signs or symptoms of a possible serious side effect, including:

  • Confusion, agitation, seeing or hearing things that are not there, change in mood or behavior, delirium, self-injury

  • Seizures

  • Blistering, peeling, red skin rash

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing

Less serious side effects

  • Nausea

  • Vomiting

  • Headache 

Find more detailed information about Tamiflu side effects and how to avoid them here.

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