Ondansetron is used to prevent nausea and vomiting associated with cancer chemotherapy or radiation therapy, or nausea and vomiting after surgery.
This medicine may also be used to treat other conditions as decided by your doctor.
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, take it 30 minutes to 2 hours before your chemotherapy treatment.
If you are taking Ondansetron to prevent nausea and vomiting due to radiation therapy, take it 1-2 hours before your radiation therapy.
If you still feel sick or feel like you might vomit, you may take Ondansetron for up to 5 days following chemotherapy or radiation therapy.
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 tablet, oral solution, syrup, and orally disintegrating (orodispersible) tablet or film.
If you are taking an oral solution or syrup, shake the bottle well before you take it to ensure that the liquid is evenly mixed. Use the measuring spoon or cup provided to measure out your dose.
If you are taking the orodispersible tablet or film:
- Remove it from the foil or sachet only just before you take it. Do not leave the orodispersible tablet or film exposed to air. Do not push through the foil or sachet 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. Slowly open the sachet of the orodispersible film using only the tear tag with dry hands.
- Place the orodispersible tablet or film directly on your tongue as soon as it is taken out of the packaging. The orodispersible tablet or film will immediately start to melt on the tongue. It can then be swallowed with or without water.
The dose of this medicine will be decided by your doctor. Your doctor will advise you on the course of your 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 a 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.
Do not take Ondansetron if you ever had an allergic reaction (rashes, breathlessness, swollen eyes) to similar medicines such as granisetron.
Alert your doctor if you have a congenital long QT syndrome (heart disorder that is present from birth) as Ondansetron may not be suitable for you.
Do not take this medicine with apomorphine (medicine for Parkinson's disease).
Inform your doctor if you have:
- liver disease
- heart disease e.g. fast and irregular heartbeat, heart failure
- electrolyte imbalance (imbalance of minerals e.g. potassium, magnesium in the body)
- bowel problems e.g. bowel obstruction
- phenylketonuria (an inherited disorder where your body is not able to break down the amino acid phenylalanine)
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 elderly person. Children and elderly people may be more sensitive to the side effects.
For as long as you are taking Ondansetron, you may need to have regular heart check-up or blood tests to check your body’s response to this medicine. Your doctor will advise you about how often you need to have these tests.
Some genetic traits can affect this medicine’s efficacy. Individuals who are ultrarapid metaboliser of CYP2D6 may respond poorer to this medicine. 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, flushing, tiredness, anxiety, difficulty sleeping, constipation, diarrhoea, hiccups and fever.
Some side effects may need immediate medical help. Alert your doctor quickly if you experience any of the following:
- chest pain, shortness of breath, irregular heartbeat
- uncontrollable movements such as twitching and jerking, fits or seizures
- light headedness, loss of consciousness
- rashes, breathlessness, swelling of the face, eyes or mouth
Inform your doctor if any of these side effects do not go away or are severe, or if you experience other side effects.
Inform your doctor and pharmacist if you are taking any of these medicines:
- medicines for heart disease or high blood pressure e.g. amiodarone, atenolol, timolol
- medicines for epilepsy (seizures or fits) e.g. carbamazepine, phenytoin
- medicines for depression e.g. mirtazapine, fluoxetine, sertraline, venlafaxine, escitalopram
- medicines for cancer e.g. doxorubicin, daunorubicin, trastuzumab
- tramadol (medicine for moderate to severe pain)
- erythromycin (antibiotic)
- rifampicin (medicine for TB)
- ketoconazole (medicine for fungal infection)
- dexamethasone (anti-inflammatory medicine)
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.
Store in a cool, dry place away from the reach of children.
The orodispersible tablet or film must be kept in its original packaging.
Medicines must not be used past the expiry date.