Ondansetron Hydrochloride Injection Ip is given to achieve instant relief from symptoms caused by cancer chemotherapy and surgery, that are vomiting and nausea. Both symptoms are caused by natural substance called serotonin, whose action is blocked by this medicine.2ml solution is packed in vial and one pack contains 10 vials of 2ml each. Vomiter injection is meant for I.M./I.V. use. It starts to work within about 30 minutes and its effects last 8-12 hours. The dosage depends upon the medical condition and age of the patient.