Zofran

Before taking this medicine

Do not take Zofran (ondansetron) if you are allergic to ondansetron or any tablet ingredient, or if you are taking apomorphine. Using ondansetron with apomorphine can cause a severe drop in blood pressure and loss of consciousness. Ondansetron should be avoided in people with congenital long QT syndrome. Extra caution and ECG monitoring are needed if you have abnormal electrolyte levels, heart failure or heart rhythm problems, or take other medicines that prolong the QT interval. Ondansetron can cause serious heart rhythm disturbances. Serotonin syndrome has been reported, particularly when ondansetron is used with other medicines that affect serotonin. If it is suspected, ondansetron should be stopped and treatment started. Serious allergic reactions, including anaphylaxis and narrowing of the airways, also require stopping treatment and prompt medical care. Reduced blood flow to the heart has been reported after oral use; patients should be monitored or advised about its signs and symptoms. Ondansetron may also mask worsening bowel blockage or stomach swelling after abdominal surgery or during chemotherapy-related nausea and vomiting. Monitoring for reduced bowel activity is important, especially in people at risk of bowel obstruction.