Butyrophenones are typically administered as a single injection at the end of surgery. Adverse effects include prolongation of the QT interval on EKG. Medications include droperidol and haloperidol. Phenothiazines are particularly effective in treating opioid-induced PONV. Adverse effects are dose-dependent and include sedation and extrapyramidal symptoms. Medications include promethazine and prochlorperazine. Neurokinin 1 (NK1) receptor antagonists prevent an emetic signal from being transmitted. Medications include aprepitant and rolapitant. Histamine receptor antagonists can be administered by multiple routes, including orally, intramuscularly, or rectally. Adverse effects include dry mouth, sedation, and urinary retention. Medications include dimenhydrinate and diphenhydramine. Propofol, an anesthetic medication, confers its own antiemetic properties.The 2020 Cochrane Anaesthesia Review Group review of Drugs for preventing postoperative nausea and vomiting in adults
after general anaesthesia: a network meta-analysis (Review)  demonstrated that combination therapy is more effective than single anti-emetic, and that dexamethasone and ondansetron (a commonly used combination) are two of the most effective anti-emetics for PONV. The review adds robust evidence of efficacy for drugs in newer classes, such as aprepitant or fosapreitant, or newer agents in familiar classes, such as ramosetron. The review does not cover the cost effectiveness of the agents included and, despite increased efficacy for newer novel agents, this may preclude their immediate utilisation in anaesthetic practice. Alternative medicine
In conjunction with antiemetic medications, at least one study has found that application to the pericardium meridian 6 acupressure point produced a positive effect in relieving PONV. Another study found no statistically significant difference.
Anesthetic risk factors include the use of volatile anesthetics, nitrous oxide (N2O), opioids, and longer duration of anesthesia. Patient factors that confer increased risk for PONV include female gender, obesity, age less than 16 years, past history of motion sickness or chemotherapy-induced nausea, high levels of preoperative anxiety, and patients with history of PONV. Smokers and the elderly often have a decreased risk for PONV. A risk-stratification method created by Apfel et al has been developed to determine a patients risk for PONV. The presence of 0, 1, 2, 3, or 4 of any of the following risk factors corresponds to a PONV respective risk of 10, 20, 40, 60, and 80%.- Female gender
- Non-smoking
- History of PONV or motion sickness
- Expectant use of postoperative opioid medications

Prevention
Treatment options to prevent PONV include medications such as antiemetics (for example, ondansetron or dexamethasone) or other drugs including tropisetron, dolasetron, cyclizine, and granisetron. Droperidol may cause QT prolongation and is not frequently used. Other approaches to reduce PONV include decision on the types of anaesthetic used during surgery and intravenous (IV) dextrose solutions. Increasing the IV fluids during surgery by giving additional fluid while the person is under general anaesthesia may reduce the risk of nausea/vomiting after surgery. For minor surgical procedures, more research is needed to determine the risks and benefits of this approach. Management
Because  currently no single antiemetic available is especially effective on its own, experts recommend a multimodal approach.