NZ Formulary



What does it do?

Oseltamivir is used to treat and prevent influenza (‘the flu’).

How should you take it?

Take oseltamivir regularly as directed with food. Keep taking it until the course is finished, even if you start to feel better.
Take the capsules with a glass of water.
Measure the liquid carefully with an oral syringe or measuring spoon. Shake the bottle well before measuring each dose.

You need to start taking oseltamivir within 2 days of getting symptoms.

What if you forget a dose?

Take the missed dose as soon as possible and continue as directed.

Can you take other medicines?

Tell your pharmacist or doctor about all medicines or treatments that you may be taking, including vitamins, herbal products or recreational drugs.

What side effects might you notice?

Side EffectsRecommended action

Symptoms of allergy including: skin rash, itching, swelling, trouble breathing


Blood in bowel motions, severe or persistent diarrhoea, abdominal pain

Tell your doctor immediately

Unusual behaviour or thinking

Tell your doctor

Nausea, vomiting


Tell your doctor if troublesome

If you notice any other effects, discuss them with your doctor or pharmacist.

Other information:

  • Tell your doctor if you have kidney problems, or have ever had a seizure.
  • Tell your doctor if you are pregnant, planning to become pregnant, or breastfeeding.
  • Store oseltamivir liquid as directed. Once the course is finished, take any leftover liquid back to your pharmacy.