Which medication is commonly used for managing symptoms in patients with chemotherapy-induced nausea?

Ondansetron is commonly used for managing symptoms in patients with chemotherapy-induced nausea because it is a serotonin 5-HT3 receptor antagonist. This medication works by blocking the action of serotonin, a chemical in the body that can trigger nausea and vomiting, particularly after chemotherapy treatments. Ondansetron is effective in preventing both acute and delayed nausea, making it a popular choice in oncology for patients undergoing chemotherapy.

In contrast, the other medications listed do not have the same level of effectiveness in addressing nausea caused by chemotherapy. Codeine is an opioid and is primarily used for pain management rather than for nausea. Diphenhydramine is an antihistamine that can help with motion sickness and allergies but may not be effective enough for nausea from chemotherapy. Propranolol is a beta-blocker that is mainly used for conditions such as hypertension and anxiety, and it does not have a direct role in managing chemotherapy-induced nausea. Thus, ondansetron is the appropriate choice for the management of symptoms associated with chemotherapy.