What is the drug of choice for nausea and vomiting?

Ondansetron is considered the drug of choice for nausea and vomiting primarily due to its targeted mechanism of action and safety profile. It is a selective serotonin 5-HT3 receptor antagonist, which means it works by blocking the action of serotonin, a neurotransmitter that can trigger nausea and vomiting, especially in situations such as chemotherapy or post-operative recovery.

The effectiveness of ondansetron is well-documented, particularly in acute settings where rapid relief from nausea is necessary. It has a rapid onset, making it suitable for both adults and children, and it is often preferred in medical settings for its lower side effects compared to other antiemetics.

Other options, while they may be effective in certain contexts, do not match the broad application and favorable profile of ondansetron. For example, metoclopramide can be used for nausea but is primarily a prokinetic agent and has a risk of adverse effects like tardive dyskinesia when used long-term. Hydrochlorothiazide is a diuretic, not indicated for nausea. Promethazine can also be effective but tends to have sedative properties and a higher risk of side effects, making ondansetron a preferable choice in many cases.