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-HT3 receptor antagonists. It works by blocking the action of serotonin, a natural substance that may cause nausea and vomiting.
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 taken 30 minutes before the start of chemotherapy, 1 to 2 hours before the start of radiation therapy, or 1 hour before surgery. Additional doses are sometimes taken one to three times a day during chemotherapy or radiation therapy and for 1 to 2 days after the end 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. Instead, 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.
This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.
Unless your doctor tells you otherwise, continue your usual diet.
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.
blurred vision or vision loss
swelling of the eyes, face, lips, tongue, throat, hands, feet, ankles, or lower legs
difficulty breathing or swallowing
shortness of breath
dizziness, light-headedness, or fainting
fast, slow or irregular heartbeat
hallucinations (seeing things or hearing voices that do not exist)
nausea, vomiting, or diarrhea
loss of coordination
stiff or twitching muscles
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.
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). Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.
In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.
sudden loss of vision for a short time
dizziness or lightheadedness
irregular heart beat
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.
It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.
Last Revised - 01/15/2015
AHFS® Consumer Medication Information. © Copyright, 2015. The American Society of Health-System Pharmacists, Inc., 7272 Wisconsin Avenue, Bethesda, Maryland. All Rights Reserved. Duplication for commercial use must be authorized by ASHP.