Safely Buy Zofran Injection ( Ondansetron ) from Canada Prescriptions Plus.


This medication is used alone or with other medications to prevent nausea and vomiting caused by cancer drug treatment (chemotherapy) and radiation therapy.

Ondansetron is used to prevent and treat nausea and vomiting after surgery.

Ondansetron works by blocking one of the body’s natural substances (serotonin) that causes vomiting.

Use and Dosage

The dosage of Zofran Injection may vary depending on the specific situation and the healthcare provider’s instructions. Administered as an intravenous (IV) or intramuscular (IM) injection. The initial U.S. approval for Zofran Injection was in 1991.

Zofran Injection is used to prevent nausea and vomiting associated with cancer chemotherapy. The specific dosage and administration instructions may differ based on the emetogenic potential of the chemotherapy regimen. For highly emetogenic chemotherapy, a maximum initial ondansetron dose of 16 mg IV infused over 15 minutes may be used. A single IV dose greater than 16 mg is not recommended. Additional doses may be given 4 hours after the first dose and 8 hours after the first dose.

Ondansetron can interact with certain medications. For example, mitotane, nefazodone, and nelfinavir may affect the metabolism of ondansetron, potentially increasing its levels or effects. Caution and monitoring are advised when coadministering ondansetron with these medications inform the healthcare provider about all medications being taken to ensure safe and effective use of Zofran Injection.

Side Effects

Headache, fever, lightheadedness, dizziness, drowsiness, tiredness, constipation, or redness/pain/burning at the injection site may occur. If these effects last or get worse, tell your doctor promptly.

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor right away if you have any serious side effects, including stomach pain, muscle stiffness/spasms, or vision changes (such as temporary loss of vision, blurred vision, or uncontrollable eye movements).

Get medical help right away if you have any very serious side effects, including chest pain, slow/fast/irregular heartbeat, severe dizziness, or fainting.

This medication may increase serotonin and rarely cause a very serious condition called serotonin syndrome/toxicity. The risk increases if you are also taking other drugs that increase serotonin, so tell your doctor or pharmacist about all the drugs you take (see Drug Interactions section). Get medical help right away if you develop some of the following symptoms: fast heartbeat, hallucinations, loss of coordination, severe dizziness, severe nausea/vomiting/diarrhea, twitching muscles, unexplained fever, and unusual agitation/restlessness.

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, or trouble breathing.

This is not a complete list of side effects. If you notice other effects not listed above, contact your doctor or pharmacist.


  • Before using ondansetron, tell your doctor or pharmacist if you are allergic to it; or to other serotonin blockers (such as granisetron); or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.
  • Before using this medication, tell your doctor or pharmacist your medical history, especially of: irregular heartbeat, liver disease, and stomach/intestinal problems (such as recent abdominal surgery, ileus, and swelling).
  • Ondansetron may cause a condition that affects the heart rhythm (QT prolongation). QT prolongation can rarely cause serious (rarely fatal) fast/irregular heartbeat and other symptoms (such as severe dizziness, and fainting) that need medical attention right away.
  • The risk of QT prolongation may be increased if you have certain medical conditions or are taking other drugs that may cause QT prolongation. Before using ondansetron, tell your doctor or pharmacist of all the drugs you take and if you have any of the following conditions: certain heart problems (heart failure, slow heartbeat, QT prolongation in the EKG), family history of certain heart problems (QT prolongation in the EKG, sudden cardiac death).
  • Low levels of potassium or magnesium in the blood may also increase your risk of QT prolongation. This risk may increase if you use certain drugs (such as diuretics/”water pills”) or if you have conditions such as severe sweating, diarrhea, or vomiting. Talk to your doctor about using ondansetron safely.
  • This drug may make you dizzy, drowsy, or blur your vision. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness or clear vision until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).
  • Infants younger than 5 months may be more sensitive to the effects of this drug, especially diarrhea.
  • Older adults may be more sensitive to the side effects of this drug, especially QT.
  • During pregnancy, this medication should be used only when needed. It may harm an unborn baby. Discuss the risks and benefits with your doctor.
  • It is unknown if this drug passes into breast milk. Consult your doctor before breast-feeding.

Forms and Strengths

Zofran Injection is available in the following forms and strengths:

  • Zofran Injection Syrup:
    • 4mg/2mL


What happens if I miss a dose?

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 for the missed dose.

What happens if I overdose?

Seek emergency medical attention.

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

What to avoid?

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



Additional information

Brand Name:

Zofran Injection

Scientific Name:


Other Names:




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