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

Zofran is used to prevent nausea and vomiting that may be caused by surgery, cancer chemotherapy, or radiation treatment.

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

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

You should not use Zofran if you are allergic to ondansetron or to similar medicines such as dolasetron (Anzemet), granisetron (Kytril), or palonosetron (Aloxi).

Zofran orally disintegrating tablets may contain phenylalanine. Tell your doctor if you have phenylketonuria (PKU).

Serious side effects include blurred vision or temporary vision loss (lasting from only a few minutes to several hours), slow heart rate, trouble breathing, anxiety, agitation, shivering, feeling like you might pass out, and urinating less than usual or not at all. Stop taking Zofran and call your doctor at once if you have any of these side effects. Ondansetron may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert.

Before taking this medicine

You should not use Zofran if:

• you are also using apomorphine (Apokyn); or

• you are allergic to ondansetron or similar medicines (dolasetron, granisetron, palonosetron).

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

• liver disease;

• an electrolyte imbalance (such as low levels of potassium or magnesium in your blood);

• congestive heart failure, slow heartbeats;

• a personal or family history of long QT syndrome; or

• a blockage in your digestive tract (stomach or intestines).

Zofran is not expected to harm an unborn baby. Tell your doctor if you are pregnant.

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.

Ondansetron is not approved for use by anyone younger than 4 years old.

Zofran orally disintegrating tablets may contain phenylalanine. Tell your doctor if you have phenylketonuria (PKU).

Take Zofran exactly as prescribed by your doctor. Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.

Zofran can be taken with or without food.

The first dose is usually taken before the start of your surgery, chemotherapy, or radiation treatment. Follow your doctor's dosing instructions very carefully.

Take the regular tablet with a full glass of water.

To take the orally disintegrating tablet (Zofran ODT):

• Keep the tablet in its blister pack until you are ready to take it. Open the package and peel back the foil. Do not push a tablet through the foil or you may damage the tablet.

• Use dry hands to remove the tablet and place it in your mouth.

• Do not swallow the tablet whole. Allow it to dissolve in your mouth without chewing.

• Swallow several times as the tablet dissolves.

Measure liquid medicine with the dosing syringe provided, or with a special dose-measuring spoon or medicine cup. If you do not have a dose-measuring device, ask your pharmacist for one.

Store at room temperature away from moisture, heat, and light. Store liquid medicine in an upright position.

You should not use Zofran if:

• you are also using apomorphine (Apokyn); or

• you are allergic to ondansetron or similar medicines (dolasetron, granisetron, palonosetron).

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

• liver disease;

• an electrolyte imbalance (such as low levels of potassium or magnesium in your blood);

• congestive heart failure, slow heartbeats;

• a personal or family history of long QT syndrome; or

• a blockage in your digestive tract (stomach or intestines).

Zofran is not expected to harm an unborn baby. Tell your doctor if you are pregnant.

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.

Ondansetron is not approved for use by anyone younger than 4 years old.

Zofran orally disintegrating tablets may contain phenylalanine. Tell your doctor if you have phenylketonuria (PKU).

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include sudden loss of vision, severe constipation, feeling light-headed, or fainting.

Zofran may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert.

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

Call your doctor at once if you have:

• severe constipation, stomach pain, or bloating;

• headache with chest pain and severe dizziness, fainting, fast or pounding heartbeats;

• fast or pounding heartbeats;

• jaundice (yellowing of the skin or eyes);

• blurred vision or temporary vision loss (lasting from only a few minutes to several hours);

• high levels of serotonin in the body--agitation, hallucinations, fever, fast heart rate, overactive reflexes, nausea, vomiting, diarrhea, loss of coordination, fainting.

Common Zofran side effects may include:

• diarrhea or constipation;

• headache;

• drowsiness; or

• tired feeling.

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.

Zofran can cause a serious heart problem, especially if you use certain medicines at the same time, including antibiotics, antidepressants, heart rhythm medicine, antipsychotic medicines, and medicines to treat cancer, malaria, HIV or AIDS. Tell your doctor about all medicines you use, and those you start or stop using during your treatment.

Taking ondansetron while you are using certain other medicines can cause high levels of serotonin to build up in your body, a condition called "serotonin syndrome," which can be fatal. Tell your doctor if you also use:

• medicine to treat depression;

• medicine to treat a psychiatric disorder;

• a narcotic (opioid) medication; or

• medicine to prevent nausea and vomiting.

This list is not complete and many other drugs can interact with ondansetron. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Give a list of all your medicines to any healthcare provider who treats you.