Excipients (example): contains lactose monohydrate 163.75 mg per tablet (in one formulation). 

• For chemotherapy/radiotherapy-induced nausea/vomiting: 8 mg oral ~ 1–2 hours before treatment, followed by 8 mg 12 hours later; may continue as twice daily for up to ~5 days. 

• For postoperative nausea/vomiting: 16 mg one hour before induction of anesthesia (in some guidelines) — subject to local prescribing. 

Always follow doctor’s instructions, including for duration, modification in hepatic impairment.

• Headache

• Constipation or diarrhoea

• Dizziness, fatigue

• Flushing, changes in bowel habit

Rare but serious: QT prolongation, serotonin syndrome when combined with other serotonergic agents. 

Contraindicated in patients with hypersensitivity to ondansetron or excipients. 

– Use with caution in patients with congenital long QT syndrome, electrolyte abnormalities (hypokalemia, hypomagnesemia), congestive heart failure, or taking other QT-prolonging drugs. 

– Avoid concomitant use with apomorphine (risk of profound hypotension). 

– In hepatic impairment (especially severe) — dose may need adjustment or maximum daily dose limited to 8 mg/day. 

– Pregnancy & breastfeeding: should be used only if clearly needed; consult physician.

– Monitor for signs of serotonin syndrome when used with other serotonergic drugs (e.g., SSRIs, SNRIs, tramadol).

– Not indicated for general relief of nausea (should be guided by cause).

– If you miss a dose, take as soon as you remember unless close to next dose; do not double up without guidance.

– Do not self-medicate for persistent vomiting; underlying condition should be evaluated.