Is it dangerous to take zofran (ondansetron) for long periods of time?

Zofran (ondansetron): This depends on how you define a long time and what the dose is. The maximum dose was reduced a couple of years ago because of potential cardiac side effects. Nausea is generally a symptom of something else. If you are a chemotherapy patient, zofran (ondansetron) is fine. Otherwise, check with your physician as to why you are needing zofran (ondansetron).