Ondansetron injection is widely used in clinical practice for its antiemetic effect. Chemotherapy, surgery, radiotherapy and other treatments may cause nausea and vomiting in patients, so ondansetron injection is often used to provide antiemetic effect. Ondansetron is a 5-HT3 receptor antagonist, a nerve blocking antiemetic, with strong efficacy and relatively low side effects, usually not causing extrapyramidal reactions or excessive sedation, so the safety of the drug is also relatively good. Although the side effects of ondansetron injection are relatively low, it may cause severe constipation, which can affect the function of the patient’s gastrointestinal tract if it occurs during chemotherapy. Ondansetron is generally contraindicated in women who are pregnant. If a patient finds out that she is pregnant during treatment, she needs to consult with her obstetrician to consider follow-up options. If the patient does not achieve the expected antiemetic effect after ondansetron injection, it can also be combined with other antiemetic drugs, such as dexamethasone and fosaprepitant, which are more commonly used in clinical practice, and can be used in diphtheria or triple antiemetic drugs, which generally have better antiemetic effects.