India · Paediatric mg/kg & Adult · Vomiting · Gastroenteritis · CINV · PONV · Emeset · Vomikind · Zofran
| Patient | Indication | Dose | Frequency | Notes |
|---|---|---|---|---|
| Child ≥ 6 months | Vomiting / gastroenteritis | 0.15 mg/kg (max 4 mg) | Every 8h PRN | Max 3 doses/day |
| Child ≥ 6 months | CINV — moderate chemo | 0.15 mg/kg (max 8 mg) | 15 min before chemo, then every 8h × 3 doses | Give before chemo |
| Child ≥ 6 months | CINV — high emetogenic | 0.15 mg/kg IV (max 8 mg) | Every 4h × 3 doses day 1 | Add dexamethasone |
| Child ≥ 2 yrs | PONV | 0.1 mg/kg IV (max 4 mg) | Single dose at end of surgery | IV slow bolus |
| Adult | Vomiting / acute nausea | 4–8 mg oral | Every 8–12h PRN | Max 32 mg/day oral |
| Adult | CINV — moderate | 8 mg oral or 8 mg IV | Before chemo, then every 8–12h | Oral preferred if tolerated |
| Adult | CINV — high emetogenic | 8 mg IV slow infusion | 30 min before, then every 4h × 2 | + Dexamethasone + NK1 |
| Adult | PONV | 4 mg IV slow | Single dose at end of surgery | Do not exceed 4 mg single IV |
| Adult | Pregnancy NVP | 4 mg oral | Every 8h | After 10 weeks, first-line options preferred |
Ondansetron is a selective serotonin 5-HT3 receptor antagonist and one of the most commonly prescribed antiemetics in India across all age groups. It is available as Emeset, Vomikind, Ondem, and Zofran in syrup, tablet, oral-dissolving tablet (ODT), and IV forms. Its effectiveness in preventing and treating vomiting from diverse causes — gastroenteritis, surgery, chemotherapy, radiotherapy, and pregnancy — makes it a near-universal choice in Indian emergency departments, paediatric wards, and oncology units.
In paediatric practice, ondansetron has become the antiemetic of choice for acute gastroenteritis-associated vomiting in children aged 6 months and above. A landmark benefit of ondansetron in this context is that a single dose can settle vomiting sufficiently to allow oral rehydration — reducing the need for IV cannulation and hospitalisation in children presenting to casualty with gastroenteritis. The IAP endorses this use.
The standard paediatric dose for acute vomiting and gastroenteritis is 0.15 mg/kg per dose, with a maximum of 4 mg per dose for children. It may be repeated every 8 hours as needed, for a maximum of 3 doses per 24 hours in the acute setting. Ondansetron should not be used in children under 6 months — its safety and efficacy in this age group have not been established, and the neonatal serotonin system is immature. The oral syrup (Emeset/Vomikind 2mg/5ml) is the preferred formulation for younger children, with ODT tablets convenient for older children who may resist syrup.
In oncology, ondansetron is the backbone of CINV prophylaxis for moderately and highly emetogenic chemotherapy regimens. For moderately emetogenic chemo (e.g. carboplatin, cyclophosphamide, doxorubicin-based): ondansetron 8 mg oral or IV before chemotherapy, then every 8–12 hours for 1–2 days. For highly emetogenic chemo (cisplatin-based), ondansetron IV is combined with dexamethasone and an NK1 receptor antagonist (aprepitant) for optimal control — ondansetron monotherapy is insufficient for cisplatin-containing regimens.
Ondansetron causes dose-dependent QTc prolongation. The risk is highest with IV administration, at high doses, and in patients with pre-existing risk factors (long QT syndrome, hypokalaemia, hypomagnesaemia, bradycardia). Key clinical rules: the maximum single IV dose in adults is 16 mg slow infusion (never bolus), and the total maximum single adult IV dose should not exceed 32 mg per day. Avoid combination with other QT-prolonging drugs — particularly azithromycin (see Azithromycin page), haloperidol, and methadone. Correct electrolyte abnormalities before IV ondansetron in high-risk patients.
Ondansetron is widely used in India for nausea and vomiting of pregnancy (NVP), particularly in the first trimester when vomiting is most severe. While earlier studies raised concerns about a possible association with oral clefts at first-trimester use, more recent large meta-analyses have not confirmed a clinically significant teratogenic risk. UK MHRA and FDA consider it acceptable for use in NVP after first-line options (metoclopramide, promethazine, vitamin B6) have been tried. In hyperemesis gravidarum requiring hospitalisation, IV ondansetron is commonly used in India. Standard adult doses apply in pregnancy.