Ondansetron (injection)

Ondansetron is used to stop nausea and vomiting that may occur with certain cancer treatments (chemotherapy) in adults and children who are at least 6 months old.

Ondansetron is also used to stop nausea and vomiting that may occur after surgery in adults and children who are at least 1 month old.

Ondansetron may be used for reasons not mentioned in this medication guide.

Tell your doctor about all the other medicines you take. Some drugs should not be used with ondansetron.

You should not use ondansetron if you are allergic to ondansetron or similar medicines (dolasetron, granisetron, palonosetron).

Some drugs should not be used with ondansetron. Your treatment plan may change if you also use apomorphine.

Tell your doctor if you have or have ever had:

• a heart rhythm disorder such as long QT syndrome (in you or a family member);
• an electrolyte imbalance (such as low blood levels of potassium or magnesium);
• congestive heart failure, slow heartbeats;
• obstruction in the stomach or intestines, a change in bowel habits;
• surgery on your stomach or intestines; or
• severe liver disease.

Tell your doctor if you also use stimulant medicine, opioid medicine, herbal products, or medicine for depression, mental illness, Parkinson's disease, migraine headaches, serious infections, or prevention of nausea and vomiting. An interaction with ondansetron could cause a serious condition called serotonin syndrome.

Tell your doctor if you are pregnant or breastfeeding.

Get emergency medical help if you have signs of an allergic reaction: hives, difficulty breathing, swelling of your face, lips, tongue, or throat.

Seek medical attention right away if you have symptoms of serotonin syndrome, such as: agitation, hallucinations, fever, sweating, shivering, fast heart rate, muscle stiffness, twitching, loss of coordination, nausea, vomiting, or diarrhea.

Seek emergency medical help if you have signs of a heart attack: chest pain that spreads to your jaw or shoulder, nausea, and sweating.

Ondansetron may cause serious side effects. Call your doctor at once if you have:

• severe stomach pain, bloating, constipation, or any change in bowel habits; or
• dizziness, feeling light-headed, fainting, slow, fast, or uneven heartbeats.

Common side effects of ondansetron may include:

• diarrhea;
• 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.

Ondansetron is injected into a muscle, or into a vein. A healthcare provider will give you this injection.

Ondansetron is usually given before surgery, and in certain cases another dose may be given after surgery.

To prevent nausea and vomiting caused by chemotherapy, ondansetron is given 30 minutes before the start of chemotherapy. Additional doses may be given 4 and 8 hours after the first dose.

In a medical setting, it is unlikely that you will miss a dose.

In a medical setting, an overdose would be treated quickly.

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

Ondansetron can lead to a serious heart issue. Your chances of this happening may increase if you also take certain other medicines for infections, asthma, heart problems, high blood pressure, depression, mental illness, cancer, malaria, or HIV.

Many medications can interact with ondansetron. This includes both prescription and over-the-counter medicines, as well as vitamins and herbal products. Not all possible interactions are mentioned here. Inform your doctor about all other medicines you are taking.