Zofran tablets, syrup and injection all contain the active ingredient ondansetron hydrochloride dihydrate, which is a type of medicine called a 5HT3 antagonist. Ondansetron is used to prevent and treat nausea and vomiting that can be caused by chemotherapy or radiotherapy treatment for cancer, or by surgery.
What is it used for?
- Preventing and treating nausea and vomiting caused by chemotherapy for cancer in adults and children aged six months and above.
- Preventing and treating nausea and vomiting caused by radiotherapy for cancer in adults.
- Preventing and treating nausea and vomiting following surgery in adults and children aged one month and above.
How does it work?
- Zofran tablets, syrup and injection all contain the active ingredient ondansetron hydrochloride dihydrate, which is a type of medicine called a 5HT3 antagonist. (NB. Ondansetron is also available without a brand name, ie as the generic medicine.) Ondansetron is used to prevent and treat nausea and vomiting that can be caused by chemotherapy or radiotherapy treatment for cancer, or by surgery.
- Vomiting is controlled by an area of the brain called the vomiting centre.
How is it given?
- Ondansetron can be given by mouth as tablets, syrup or tablets that melt on the tongue, by injection into a muscle or vein, by drip into a vein (intravenous infusion), or by suppository.
- Ondansetron tablets and syrup can be taken either with or without food.
Use with caution in
- People who are allergic to other 5HT3 antagonists, eg granisetron.
- Decreased liver function.
- People with a blockage in the gut (intestinal obstruction).
- People with a slow or irregular heartbeat (arrhythmia) or heart failure.
- People with a personal or family history of an abnormal heart rhythm seen on a heart monitoring trace (ECG) as a 'prolonged QT interval'.
- People taking medicines that can cause a 'prolonged QT interval' (your doctor will know, but see end of this factsheet for some examples).
- People taking medicines to treat an irregular heartbeat (antiarrhythmics) or beta-blocker medicines.
- People with disturbances of the levels of salts (electrolytes) such as potassium and magnesium in their blood.
- People having surgery on the adenoids or tonsils.
Not to be used in
- People with known hypersensitivity or allergy to any ingredient.
- Zofran tablets contain lactose and are not suitable for people with rare hereditary problems of galactose intolerance, Lapp lactase deficiency or glucose-galactose malabsorption.
- This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.
If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.
Pregnancy and breastfeeding
Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.
- The safety of this medicine during pregnancy has not been established. It is not recommended for use in pregnant women unless considered essential by your doctor. Seek medical advice from your doctor.
- This medicine may pass into breast milk. Mothers who need treatment with this medicine should not breastfeed their infants during treatment. Seek medical advice from your doctor.
Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.
- Flushing or sensation of warmth.
- Involuntary movements.
- Slow heart rate (bradycardia).
- Irregular heartbeats (arrhythmias).
- Chest pain.
- Low blood pressure (hypotension).
- Alteration in results of liver function tests.
- Allergy to active ingredient (hypersensitivity).
- Dizziness an temporary visual disturbances when the medicine is administered by injection into a vein.
- Abnormal heart rhythm seen as a 'prolonged QT interval' on a heart monitoring trace or ECG.
The side effects listed above may not include all of the side effects reported by the medicine's manufacturer. For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.
How can this medicine affect other medicines?
It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while having treatment with this one, to make sure that the combination is safe.
Ondansetron should not be used in combination with apomorphine (used to treat Parkinson's disease).
The following medicines may increase the removal of ondansetron from the body and could therefore make it less effective:
Small studies suggest that ondansetron may reduce the painkilling effect of tramadol.
There may be an increased risk of an abnormal heart rhythm if ondansetron is taken with other medicines that can affect the heart, such as the following:
- antiarrhythmics (medicines to treat abnormal heartbeats), eg amiodarone, procainamide, disopyramide, sotalol
- anti-cancer medicines that can affect the heart, for example trastuzumab or anthracyclines such as doxorubicin
- the antihistamines astemizole, mizolastine or terfenadine
- arsenic trioxide
- certain antidepressants, eg amitriptyline, imipramine, maprotiline
- certain antimalarials, eg halofantrine, chloroquine, quinine, mefloquine, Riamet
- certain antipsychotics, eg thioridazine, chlorpromazine, sertindole, haloperidol
- intravenous erythromycin or pentamidine
- medicines that can alter the levels of salts such as potassium or magnesium in your blood, eg diuretics such as furosemide.