Oseltamivir (By mouth)


Oseltamivir (oh-sel-TAM-i-vir)

Treats and helps prevent influenza.

Brand Name(s)


When This Medicine Should Not Be Used

How to Use This Medicine

Capsule, Liquid

  • Take your medicine as directed. Do not take this medicine for any illness other than the flu.
  • Start taking this medicine as soon as possible after flu symptoms start or after you are exposed to the flu (within the first 2 days).
  • Shake the oral liquid medicine before each use. Measure the liquid medicine with the oral dispenser that came with the medicine. Ask your pharmacist for an oral measuring spoon or syringe if you do not have one.
  • 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 your doctor or pharmacist if you have any questions.
  • Read and follow the patient instructions that come with this medicine. Talk to your doctor or pharmacist if you have any questions.

If a dose is missed:

  • If you miss a dose and your next dose is duewithin 2 hours, skip the missed dose and take your medicine at the normal time. Do not use extra medicine to make up for a missed dose.
  • If you miss a dose and your next dose is due in more than 2 hours, take the missed dose as soon as you can. Then take your next dose at the normal time, and go back to your regular schedule.

How to Store and Dispose of This Medicine

  • Capsules: Store at room temperature, away from heat, moisture, and direct light.
  • Oral liquid: Store in the refrigerator and use within 17 days. Do not freeze. You may also store the medicine at room temperature, but use it within 10 days. Throw away any medicine that has not been used within this time.
  • Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any outdated medicine or medicine no longer needed.
  • Keep all medicine out of the reach of children. Never share your medicine with anyone.

Drugs and Foods to Avoid

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • Do not use this medicine if you have received the live influenza vaccine (nasal mist) in the past 2 weeks or if you will receive the vaccine within 48 hours, unless your doctor says it is okay.

Warnings While Using This Medicine

  • Make sure your doctor knows if you are pregnant or breastfeeding, or if you have kidney disease, liver disease, heart disease, lung disease, or a weakened immune system.
  • This medicine is not a substitute for a yearly flu shot. It also will not keep you from getting a bacterial infection.
  • Serious skin reactions can occur with this medicine. Stop using this medicine and check with your doctor right away if you have a red skin rash, blisters, peeling or loose skin, skin sores, or fever.
  • Tell the doctor about any unusual thoughts or behaviors that begin to happen. People who have the flu sometimes become confused, have seizures, or start to hear or see things that are not really there.
  • Call your doctor if your symptoms do not improve or if they get worse.
  • The liquid form of this medicine contains sorbitol. Make sure your doctor knows if you have hereditary fructose intolerance.

Possible Side Effects While Using This Medicine

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Blistering, peeling, red skin rash
  • Confusion, anxiety, agitation, trouble sleeping, change in mood or behavior, seizures
  • Fever, chills, cough, sore throat, and body aches

If you notice these less serious side effects, talk with your doctor:

  • Mild skin rash
  • Nausea, vomiting, diarrhea, stomach pain, or upset stomach

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Version Info

  • Last reviewed on 8/4/2014

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (www.hon.ch)

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- 2013 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.