O-Set is a brand of ondansetron, a medicine that helps prevent and treat nausea and vomiting. It is commonly used in cancer patients receiving chemotherapy or radiotherapy, and also after surgery.

Mechanism of Action

Ondansetron works by blocking serotonin (5-HT₃) receptors in both the gut and the brain. Serotonin normally triggers the vomiting reflex during chemotherapy, surgery, or stomach irritation. By blocking these signals, ondansetron reduces the urge to vomit.

Uses 

• Nausea and vomiting caused by chemotherapy

• Nausea and vomiting caused by radiotherapy

• Postoperative nausea and vomiting (after surgery)

• Sometimes used in severe vomiting due to stomach infections or other causes (doctor’s advice only)

  Adverse Effects

  Most people tolerate it well, but some may experience:

  • Headache

  • Constipation or diarrhea

  • Dizziness or lightheadedness

  • Tiredness or weakness