Ondansetron is known to be a highly selective 5-HT3 receptor antagonist. 5HT3 is a substance released during chemotherapy or radiation therapy, this substance is present in the small intestine and causes the vomiting reflex.

A 2014 study of 90 patients receiving chemotherapy found that about half had nerve damage, and 6.7% thought it was a symptom that doctors often overlook. The extent of damage depends on the type of chemotherapy drug used.