ondansetron (injection)

Pronunciation: on DAN se tron

Brand: Zofran

What is the most important information I should know about ondansetron?

You should not use ondansetron if you are also using apomorphine (Apokyn).

What is ondansetron?

Ondansetron blocks the actions of chemicals in the body that can trigger nausea and vomiting.

Ondansetron is used to prevent nausea and vomiting that may be caused by surgery or by medicine to treat cancer (chemotherapy).

Ondansetron injection is not for preventing nausea or vomiting that is caused by factors other than chemotherapy or surgery.

Ondansetron may be used for purposes not listed in this medication guide.

What should I discuss with my healthcare provider before receiving ondansetron?

You should not use this medicine if you are allergic to ondansetron, or if you are also using apomorphine (Apokyn).

To make sure ondansetron is safe for you, tell your doctor if you have:

  • liver disease;
  • heart disease, congestive heart failure, a heart rhythm disorder;
  • an electrolyte imbalance (such as low levels of potassium or magnesium in your blood);
  • a personal or family history of Long QT syndrome; or
  • if you take a diuretic or "water pill."

FDA pregnancy category B. Ondansetron is not expected to harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment.

It is not known whether ondansetron passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breast-feeding a baby.

How is ondansetron given?

Ondansetron is injected into a vein through an IV. A healthcare provider will give you this injection.

Ondansetron is usually given just before your surgery begins, or within 2 hours after surgery.

To prevent nausea and vomiting caused by chemotherapy, ondansetron is given 30 minutes before the start of chemotherapy. A second and third dose of ondansetron are sometimes given 4 hours and 8 hours after the first dose.

What happens if I miss a dose?

Because you will receive ondansetron in a clinical setting, you are not likely to miss a dose.

What happens if I overdose?

Since this medicine is given by a healthcare professional in a medical setting, an overdose is unlikely to occur.

What should I avoid after receiving ondansetron?

This medicine may cause blurred vision and may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert and able to see clearly.

What are the possible side effects of ondansetron?

Get emergency medical help if you have any of these signs of an allergic reaction: rash, hives; fever, chills, difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • headache with chest pain and severe dizziness, fainting, fast or pounding heartbeats;
  • blurred vision or temporary vision loss (lasting from only a few minutes to several hours);
  • severe constipation;
  • a light-headed feeling, like you might pass out;
  • little or no urinating;
  • high levels of serotonin in the body --agitation, hallucinations, fever, fast heart rate, overactive reflexes, nausea, vomiting, diarrhea, loss of coordination, fainting; or
  • severe skin reaction --fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain, followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.

Common side effects may include:

  • diarrhea or constipation;
  • drowsiness;
  • fever; or
  • headache.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect ondansetron?

There are many other medicines that can increase your risk of heart rhythm problems if you use them together with ondansetron.

Tell your doctor about all medicines you use, and those you start or stop using during your treatment with ondansetron, especially:

  • anagrelide;
  • droperidol;
  • methadone;
  • an antibiotic --azithromycin, clarithromycin, erythromycin, levofloxacin, moxifloxacin, pentamidine;
  • cancer medicine --arsenic trioxide, vandetanib;
  • an antidepressant --citalopram, escitalopram;
  • anti-malaria medication --chloroquine, halofantrine;
  • heart rhythm medicine --amiodarone, disopyramide, dofetilide, dronedarone, flecainide, ibutilide, quinidine, sotalol; or
  • medicine to treat a psychiatric disorder --chlorpromazine, haloperidol, pimozide, thioridazine.

This list is not complete. Other drugs may interact with ondansetron, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.

Where can I get more information?

Your pharmacist can provide more information about ondansetron.


Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

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