Why is this medicine prescribed?
Ondansetron is used to prevent nausea and vomiting caused by cancer chemotherapy, radiation therapy, and surgery. Ondansetron is in a class of medications called serotonin 5-HT 3 receptor antagonists. It works by blocking the action of serotonin, a natural substance that may cause nausea and vomiting.
Are there other uses for this medicine?
Ondansetron is also sometimes used to help prevent and treat nausea and vomiting during pregnancy or from other causes.
This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.
How should this medicine be used?
Ondansetron comes as a tablet, a rapidly disintegrating (dissolving) tablet, and an oral solution (liquid) to take by mouth. The first dose of ondansetron is usually given before the start of chemotherapy, radiation, or surgery. Additional doses are taken depending on the type of treatment. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand.
Take ondansetron exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.
If you are taking the rapidly disintegrating tablet, remove the tablet from the package just before you take your dose. To open the package, do not try to push the tablet through the foil backing of the blister. Use dry hands to peel back the foil backing. Gently remove the tablet and immediately place the tablet on the top of your tongue. The tablet will dissolve in a few seconds and can be swallowed with saliva.
What special precautions should I follow?
Before taking ondansetron,
- tell your doctor or pharmacist if you are allergic to this medication, any part of this medication, or any other medications, foods or substances. Tell your doctor or pharmacist about the allergy and what symptoms you had.
- some medications should not be taken with ondansetron. Other medications may cause dosing changes or extra monitoring when taken with ondansetron. Make sure you have discussed any medications you are currently taking or plan to take before starting ondansetron with your doctor and pharmacist. Before starting, stopping, or changing any medications while taking ondansetron, please get the advice of your doctor or pharmacist.
- tell your doctor if you or anyone in your family has or has ever had long QT syndrome (a rare heart problem that may cause irregular heartbeat, fainting, or sudden death), or another type of irregular heart beat or heart rhythm problem, or if you have or have ever had low blood levels of magnesium or potassium, heart failure (HF; condition in which the heart cannot pump enough blood to other parts of the body), or liver disease.
- tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking ondansetron, call your doctor.
- if you have phenylketonuria (PKU, a condition in which a special diet must be followed to prevent damage to your brain), you should know that the orally disintegrating tablets contain aspartame that forms phenylalanine.
What special dietary instructions should I follow?
Unless your doctor tells you otherwise, continue your usual diet.
What should I do if I forget to take a dose?
Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.
What should I do in case of overdose?
In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help . If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.Symptoms of overdose may include:
- sudden loss of vision for a short time
- dizziness or lightheadedness
- fainting
- constipation
- irregular heart beat
What side effects can this medicine cause?
Ondansetron may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:
- headache
- constipation
- weakness; tiredness; drowsiness
- chills
Some side effects can be serious. If you experience any of the following symptoms, call your doctor immediately or seek emergency medical treatment:
- blurred vision or vision loss
- rash, itching, hives; swelling of the eyes, face, lips, tongue, throat, hands, feet, ankles, or lower legs; hoarseness; difficulty breathing or swallowing
- chest pain; shortness of breath; dizziness, light-headedness, or fainting
- fast, slow or irregular heartbeat
- agitation; confusion; hallucinations (seeing things or hearing voices that do not exist); fever; excessive sweating; nausea, vomiting, or diarrhea; loss of coordination; stiff or twitching muscles; seizures; coma (loss of consciousness)
Ondansetron may cause other side effects. Call your doctor if you have any unusual problems while you are taking this medication.
What should I know about storage and disposal of this medication?
Keep this medication in the container it came in, tightly closed, and out of reach of children. Store the tablets and rapidly disintegrating tablets away from light, at room temperature or in the refrigerator. Store the solution in the bottle upright at room temperature and away from light, excess heat, and moisture (not in the bathroom).
Keep all medication out of sight and reach of children as many containers are not child-resistant. Always lock safety caps. Place the medication in a safe location – one that is up and away and out of their sight and reach. https://www.upandaway.org Dispose of unneeded medications in a way so that pets, children, and other people cannot take them. Do not flush this medication down the toilet. Use a medicine take-back program. Talk to your pharmacist about take-back programs in your community. Visit the FDA's Safe Disposal of Medicines website https://goo.gl/c4Rm4p for more information.What other information should I know?
Keep all appointments with your doctor.
Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.
Keep a written list of all of the prescription and nonprescription (over-the-counter) medicines, vitamins, minerals, and dietary supplements you are taking. Bring this list with you each time you visit a doctor or if you are admitted to the hospital. You should carry the list with you in case of emergencies.