Ondansetron is a 5-HT3 receptor antagonist used to prevent and treat nausea and vomiting.

Applications:

• Prevents nausea and vomiting from chemotherapy, radiation, and surgery.

• Sometimes used for severe morning sickness in pregnancy.

Side Effects:

• Common: headache, constipation, dizziness.

• Serious (rare): QT prolongation, allergic reactions, serotonin syndrome (when combined with other serotonergic drugs).

Hyoscine/Scopolamine Hydrobromide is an anticholinergic used to prevent motion sickness and treat nausea.

Applications:

• Prevents motion sickness-related nausea and vomiting.

• Used for postoperative nausea and in palliative care to reduce secretions.

Side Effects:

• Common: dry mouth, drowsiness, blurred vision, and dizziness.

• Serious (rare): confusion, hallucinations, and urinary retention.

Domperidone is a dopamine antagonist used to treat nausea, vomiting, and gastrointestinal motility disorders.

Applications:

• Relieves nausea and vomiting.

• Treats gastroparesis by enhancing stomach emptying.

• Sometimes used to increase breast milk production (off-label).

Side Effects:

• Common: dry mouth, abdominal cramps, and headache.

• Serious (rare): heart rhythm disorders, especially in elderly or high doses.