3. Ondansetron

Ondansetron

  • Ondansetron is an anti-emetic, and is used to prevent or treat sickness.
  • It starts to work within 1 - 2 hours.
Type of medicine 5HT3 antagonist anti-emetic
Used for Prevention or treatment of sickness after chemotherapy, radiotherapy or surgery
Also called Demorem®
Ondemet®
Zofran®
Zofran Melt®
Available as Tablets
Melt tablets
Syrup
Suppositories
Injection

Chemotherapy, radiotherapy and surgery may all cause the release of a chemical called serotonin (5HT) in the digestive system and the brain. This serotonin acts on receptors called 5HT3 receptors which cause sickness and feelings of sickness. Ondansetron works by blocking these 5HT3 receptors and therefore stops you from feeling or being sick.

Before taking ondansetron make sure your doctor or pharmacist knows:

  • If you are pregnant, trying for a baby or breast-feeding.
  • If you have liver problems.
  • If you have ever had heart problems such as an irregular heart beat.
  • If you think you may have a blocked bowel.
  • If you are taking other medicines, including those available to buy without a prescription, herbal or complementary medicines.
  • If you have ever had an allergic reaction to this or to any other medicine.
  • Before taking ondansetron, read the manufacturer's printed information leaflet.
  • Take ondansetron exactly as your doctor has told you to. The way you have been told to take ondansetron will depend upon the reason you are taking it. Check with your doctor or pharmacist if you are unsure.
  • If you have been prescribed ondansetron melt tablets, you should peel the foil backing off the blister pack rather than try to push the tablet through. Place the melt tablet on your tongue and allow it to dissolve before you swallow.
  • If you forget to take a dose and feel sick, take it as soon as you remember and then take the next dose when it is due. If you forget to take a dose but do not feel sick, leave out the missed dose and take you next dose when it is due. Do not take two doses together to make up for a missed dose.

If you have been given ondansetron suppositories:

  • Remove the wrapping from the suppository.
  • You may find that inserting the suppository is easier if you squat or bend forward.
  • Using your finger gently push the suppository into your rectum (back passage) as far as possible, pointed end first.
  • Remain still for a little while to help you to hold the suppository in place.
  • Wash your hands after use.
  • Ondansetron should start to work within 1 - 2 hours.
  • If you are taking ondansetron tablets or syrup and you are sick within one hour of taking a dose, take the dose again.

Along with their useful effects, all medicines can cause unwanted side-effects although not everyone experiences them. These usually improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following side-effects continue or become troublesome.

Common side-effects What can I do if I experience this
Headache Ask your pharmacist to recommend a suitable painkiller. If the headache continues, speak with your doctor
Constipation Try to eat a well balanced diet containing plenty of fibre, and drink 6 - 8 glasses of water each day
Feeling of warmth, flushing Wear light, cool clothes
Other less common side-effects include: hiccups, chest pain, uneven heart beats, dizziness especially when getting up from a lying or sitting position, and unusual body movements If any of these become troublesome, speak with your doctor

If you experience any other symptoms which you think may be due to this medicine, speak with your doctor or pharmacist.

  • Keep all medicines out of the reach and sight of children.
  • Store in a cool, dry place, away from direct heat and light.

  • If you buy any medicines check with a pharmacist that they are safe to take with your other medicines.
  • Never take more than the prescribed dose. If you suspect that you or someone else has taken an overdose of this medicine go to the accident and emergency department of your local hospital at once. Take the container with you, even if it is empty.
  • If you are having any treatment like an operation or dental treatment tell the person carrying out the treatment which medicines you are taking.
  • This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.
  • Never keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.
  • If you have any questions about this medicine ask your pharmacist.
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Further reading & references

Original Author: Helen Allen Current Version:
Last Checked: 21/10/2010 Document ID: 1434  Version: 23 © EMIS

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

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