NZ Formulary



What does it do?

Ondansetron is used to treat and prevent nausea and vomiting.

How should you take it?

Take ondansetron tablets as directed with a glass of water.
Place ondansetron wafers or ‘orodispersible’ tablets on the tongue. Allow to soften for a few seconds and then swallow.

What if you forget a dose?

Should an occasional dose be missed it need not be taken later.

Can you take other medicines?

Some medicines available without a prescription may react with ondansetron including:

  • some migraine medicines, such as sumatriptan (e.g. Sumagran Active®) or zolmitriptan (e.g. Zomig®)

Tell your pharmacist or doctor about all medicines or treatments that you may be taking, including vitamins, herbal products (e.g. St John's wort) or recreational drugs.

What side effects might you notice?

Side EffectsRecommended action

Fast or irregular heartbeat, fainting

Tell your doctor immediately

Headache, dizziness

Drowsiness, tiredness or weakness

Flushing, fever

Tingling or numbness


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 liver, heart or bowel problems.
  • Tell your doctor if you have phenylketonuria (PKU). The orodispersible tablets and wafers may contain aspartame (a source of phenylalanine).
  • Tell your doctor if you are pregnant, planning to become pregnant, or breastfeeding.