What is a common side effect of antiemetics like ondansetron used for gastroenteritis?

Ondansetron, a commonly used antiemetic for conditions like gastroenteritis, works by blocking the action of serotonin at specific receptors in the brain and gastrointestinal tract. One of the notable side effects associated with this medication is QT prolongation. This refers to an elongation of the QT interval on an electrocardiogram (ECG), which can potentially lead to life-threatening arrhythmias such as Torsades de Pointes.

The mechanism behind this side effect involves the drug's interaction with cardiac ion channels, particularly in the heart's repolarization phase. For patients receiving ondansetron, especially in high doses or those with existing risk factors (such as electrolyte imbalances or concurrent medications that also prolong the QT interval), it's crucial to monitor the ECG to prevent complications.

While other side effects mentioned, like dry mouth or headaches, may occur with ondansetron, they are generally less serious and not as clinically significant as QT prolongation. Diarrhea is not typically a side effect associated with ondansetron, as its primary role is to combat nausea and vomiting. Thus, the recognition of QT prolongation is vital for safe clinical practice when administering this medication.