Skip Ribbon Commands
Skip to main content


Drug Class: Commonly Known As: Category:
Antiviral Agent Tamiflu Adult, Children

Oseltamivir - What is it for

Oseltamivir is an antiviral which inhibits growth and shedding of Influenza A and B viruses. It prevents the influenza virus from spreading inside the body therefore helping to relieve or prevent the symptoms arising from influenza virus infection.

Oseltamivir - Side Effects, Precautions, and Contraindications

What side effects can Oseltamivir cause?

The most common side effects of Oseltamivir are:

  • Nausea, vomiting. Eat small frequent meals.
  • Diarrhoea
  • Stomachache. Take medication together with food
  • Headache

These side effects mostly occur after the first dose of the medicine and will usually stop as treatment continues. The frequency of these side effects is reduced if the medication is taken with food. Inform your doctor if the side effects become severe and bothersome.

Rare but serious side effects may manifest as the following symptoms. Contact your doctor as soon as possible, if you notice any of the following:

  • Hallucinations, unusual thoughts or behaviour that trouble you or your child, especially if they are new or getting worse.

If you or your child is often sick (vomiting) while taking the medicine, you should inform your doctor. You should also tell your doctor if the influenza symptoms get worse or the fever persists.

Before taking Oseltamivir , what precautions must I follow?

What food or medicine must I avoid when I take Oseltamivir ?

Oseltamivir - Dosage and How to Use

How should Oseltamivir be used?


You must use (or give to your child) the amount of Oseltamivir as prescribed by your doctor.

The usual dose for treatment of influenza in children depends on the age or weight (for <12 months) or body weight (for ≥12 months) of the child as indicated below

Children <12 months:

AgeRe​commended dose for 5 days (Treatment)
​<3 months​12mg twice daily
​3-5 months​20mg twice daily
​6-11 months​25mg twice daily

  *Follow weight based dosing as prescribed by your doctor if available

Children ≥ 12 months, up to adults:

Body WeightRecommended dose for 5 days (Treatment)
≤15 kg​30mg twice daily
​>15 to 23 kg​45mg twice daily
​>23 to 40 kg​60mg twice daily
​>40 kg or adult​75mg twice daily



Oseltamivir can also be used to prevent influenza following exposure to an infected individual. You must use (or give to your child) the amount of Oseltamivir as prescribed by your doctor.

Oseltamivir should be taken once daily for 10 days. It is best taken in the mornings with breakfast.

The usual dose for prevention of influenza in children depends on the age or weight (for <12 months) or body weight (for ≥12 months) of the child as indicated below:

Children <12 months*:

AgeRe​commended dose for 10 days (Prevention)
​<3 months​12mg once daily
​3-5 months​20mg once daily
​6-11 months​25mg once daily

 *Follow weight based dosing as prescribed by your doctor if available

Children ≥ 12 months, up to adults:

Body WeightRecommended dose for 10 days (Prevention)
≤15 kg​30mg once daily
​>15 to 23 kg​45mg once daily
​>23 to 40 kg​60mg once daily
​>40 kg or adult​75mg once daily


Taking Oseltamivir capsule with food will reduce the potential for stomach upset.

As powder from the capsules can be irritating to the skin and eyes, open the capsules with care. If powder comes in contact with eyes or skin, rinse with plenty of water immediately.

As Oseltamivir is very bitter and the taste can be masked by mixing the contents of the capsule(s) with sweetened liquids as indicated below:

For patients who cannot swallow the capsules:

  • Carefully open one _________mg capsule and pour all the powder into a plastic cup.
  • Add 10mL of water to the plastic cup and mix for 2 minutes.
  • Use the syringe to measure out ___________mL and discard the remaining mixture.
  • Add the mixture measured out to a small volume of one of the following sweetened liquids listed below and serve to your child.

The following sweetened liquids are:

  • Ovaltine*
  • Milo*
  • Rose syrup
  • Maple syrup
  • Cherry syrup
  • Condensed milk
  • Chocolate syrup (Nestle’s or Hershey’s)
  • Nestle’s Nesquik Plus + 50% water*
  • Melted Vanilla and Chocolate Ice Cream
  • Honey (for children ≥2 years of age)

* Allow these drinks to cool to room temperature before medication is added.

What should I do if I miss a dose?

If you forget to take (or give your child) a dose, take (or give) the missed dose as soon as you remember, except if it is near the next dose (within 2 hours). Then continue to take (or give) the Oseltamivir capsule at the usual times. Do not double or increase the dose.

If you (or your child) have missed several doses, inform your doctor and follow the advice given. If you (or your child) vomit within 15 minutes of administration, take (or give) another dose if possible.

What should I do if I overdose?

Oseltamivir - Handling

How should I handle Oseltamivir safely?

Oseltamivir - Storage

How should I store Oseltamivir ?

;#Keep away from children;#Keep in a cool, dry place, away from direct sunlight;#Store at room temperature;#

How should I dispose of Oseltamivir safely?

Oseltamivir - Additional Information

Some medication may reduce its efficacy, or increase its toxicity. Do not take (or give your child) any other medications or herbal products without consulting your doctor or pharmacist.


To date, there are no controlled studies in pregnant women and insufficient clinical experience to confirm its safety in pregnancy. However, as pregnant women might be at a higher risk of severe complications from influenza, and the benefits of treatment or prophylaxis is likely to outweigh the theoretical risks of antiviral use, individuals prescribed with Oseltamivir are highly encouraged to comply with treatment.


Breastfeeding while taking Oseltamivir can be continued. Breastfeeding provides antibodies to the infant which makes them less vulnerable. Whenever possible, breastfeed infant or express breast milk before taking Oseltamivir to minimize the infant’s exposure.

  • Updated on 10/7/2017 12:00:00 AM
  • Article contributed by Pharmacy Department KK Women's and Children's Hospital
The information provided is not intended as medical advice. Terms of use. Information provided by SingHealth

Find Your Medicines