Ondansetron (patient information)

Why is this medication 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 5-HT3receptor antagonists. It works by blocking the action of serotonin, a natural substance that may cause nausea and vomiting.

How should this medicine be used

Ondansetron comes as a tablet, a rapidly disintegrating (dissolving) tablet, and an oral solution to take by mouth. The first dose of ondansetron is usually taken 30 minutes before the start of chemotherapy, 1–2 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 1–2 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.

Other uses for this medicine

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

What special precautions should I follow

Before taking ondansetron

• tell your doctor and pharmacist if you are allergic to ondansetron, alosetron (Lotronex), dolasetron (Anzemet), granisetron (Kytril), palonosetron (Aloxi), any other medications, or any of the ingredients in ondansetron tablets or liquid. Ask your pharmacist for a list of the ingredients.
• tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking. Be sure to mention tramadol (Ultram, in Ultracet). Your doctor may need to change the doses of your medications or monitor you more carefully for side effects.
• tell your doctor if you have or have ever had 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, an inherited condition in which a special diet must be followed to prevent mental retardation), you should know that the orally disintegrating tablets contain 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 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.

Side effects

Mild side effects

Ondansetron may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• diarrhea
• headache
• constipation
• weakness
• tiredness
• dizziness

Severe side effects

Some side effects can be serious. If you experience any of the following symptoms, call your doctor immediately:

• rash
• hives
• itching
• swelling of the eyes, face, lips, tongue, throat, hands, feet, ankles, or lower legs
• hoarseness
• difficulty breathing or swallowing
• shortness of breath
• noisy, high pitched breathing

Ondansetron may cause other side effects. Call your doctor if you have any unusual problems while you are taking this medication.

What storage conditions are needed for this medicine

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 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 emergency/overdose

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.

Symptoms of overdose may include:

• sudden loss of vision for a short time
• dizziness or lightheadedness
• fainting
• constipation
• irregular heartbeat

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.

Brand names

• Zofran®
• ZofranODT®