Ondansetron is used to prevent nausea and vomiting associated with cancer chemotherapy or radiation therapy.
This medicine may also be used to treat and prevent nausea and vomiting that may occur after surgery.
Take Ondansetron exactly as directed by your doctor or according to the instructions on the label. Do not take more or less than instructed by your doctor.
If you are taking this medicine to prevent nausea and vomiting due to chemotherapy or radiation therapy, take it up to 2 hours before your treatment.
If you are taking this medicine to prevent nausea and vomiting after an operation, take it 1 hour before your operation.
You may take this medicine with or without food.
Ondansetron is available as a conventional tablet, orally disintegrating (orodispersible) tablet, oral solution, and syrup.
If you are taking an oral solution or syrup, shake the bottle well before you take the medicine to ensure that the liquid is evenly mixed. Use the measuring spoon or cup provided to measure your dose.
If you are taking the orodispersible tablet, follow these steps:
- Remove it from the foil only just before you take it. Do not leave the orodispersible tablet exposed to air. Do not push the orodispersible tablet through the foil as it is fragile and easily broken.
- Remove the orodispersible tablet with dry hands by peeling the backing off the foil and tipping the tablet onto your dry hands.
- Place the orodispersible tablet directly on your tongue as soon as it is taken out of the foil. The orodispersible tablet will immediately start to melt on the tongue. It can then be swallowed with or without water.
Do not cut, break, or crush the orodispersible tablet.
The dose of this medicine will be decided by your doctor. Your doctor will advise you on the course of treatment depending on the type and severity of your condition.
If you miss a dose and you feel sick, take the missed dose as soon as you remember then return to your normal dosing schedule.
If you miss a dose but do not feel sick, skip the missed dose and return to your normal dosing schedule.
DO NOT double a dose under any circumstances.
Alert your doctor if you have a congenital long QT syndrome (an inherited disease causing abnormally fast and erratic heartbeats) as Ondansetron may not be suitable for you.
Do not take this medicine with apomorphine (medicine used to treat Parkinson's disease, a disorder that affects the movement of a person, causing symptoms such as tremors, muscle stiffness, slowed movement and impaired balance or walking).
Inform your doctor if you have the following conditions:
- heart diseases e.g. fast and irregular heartbeat, heart failure (weakness and inability of the heart to pump blood)
- electrolyte imbalance (imbalance of essential minerals in the body) e.g. low potassium or magnesium level in the blood
- blocked bowel
- had previous surgery on the abdomen or tonsils
- liver disease
Let your doctor know if you are pregnant or breastfeeding.
Be sure to check with your doctor or pharmacist before giving Ondansetron to a child or the elderly. Children and elderly people may be more sensitive to the side effects.
Why is it important to keep my appointments with the doctor?
Keep your appointments with your doctor. Your doctor needs to monitor your condition and check your response to the medication regularly.
- Routine tests (e.g. potassium or magnesium levels, ECG [test used to record the electrical activity of the heart]) may be done while you are being treated with this medicine. Your doctor will advise you about how often you need to have these tests.
- Regular monitoring for signs and symptoms of allergic reactions, chest tightness or pain, and stomach swelling or pain may also be needed.
Some genetic traits can affect this medicine's efficacy. Individuals who are ultrarapid metaboliser of CYP2D6 may respond poorer to Ondansetron. Although not routinely done, your doctor may advise you to take genetic testing to check if this medicine is best suited for you. If you know you have this gene type, inform your doctor.
Ondansetron may cause any of the following side effects: headache, dizziness, constipation, diarrhoea, flushing, sensation of warmth, hiccups, tiredness, and anxiety.
Some side effects may need immediate medical help. Alert your doctor quickly if you experience any of the following:
- signs and symptoms of an allergic reaction e.g. rashes, breathlessness, swelling of the face, eyes or mouth
- signs and symptoms of a heart problem e.g. chest pain, tightness or pressure, difficulty breathing, wheezing
- agitation, confusion, hallucinations (seeing, hearing or feeling things that are not existent), fever, fast heartbeat, excessive sweating, muscle stiffness or spasms
- irregular, fast or abnormal heartbeat, loss of consciousness
Inform your doctor if any of these side effects do not go away or are severe, or if you experience other side effects.
Do not take this medicine with apomorphine (medicine used to treat Parkinson's disease).
Inform your doctor and pharmacist if you are taking any of these medicines:
- medicines to treat depression e.g. mirtazapine, fluoxetine, sertraline, escitalopram, venlafaxine, duloxetine
- medicines for epilepsy (fits or seizures) e.g. carbamazepine, phenytoin
- medicines for cancer e.g. doxorubicin, daunorubicin, trastuzumab
- medicines for irregular heartbeat e.g. amiodarone
- medicines for high blood pressure e.g. atenolol, timolol
- rifampicin (medicine to treat TB, a lung infection known as tuberculosis)
- lithium (medicine for mood disorders)
- ketoconazole (medicine for fungal infection)
- erythromycin (certain antibiotic)
- tramadol (strong painkiller)
This list does not include all medicines that may interact with Ondansetron.
Always notify your doctor and pharmacist if you are taking any other medicines, including herbal tonics such as traditional Chinese medicines, supplements, and medicines that you buy without a prescription.
Avoid alcohol.
Store in a cool, dry place away from the reach of children.
The orodispersible tablet must be kept in its original foil wrapper and original container. Do not store this medicine in any other container except its original.
Medicines must not be used past the expiry date.
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