Postoperative nausea and vomiting (PONV) remains one of the most common side effects following anesthesia and surgery, with reported incidences ranging from 20% to 30% in the general surgical population and exceeding 70% in high-risk groups. Beyond patient discomfort, PONV is associated with delayed recovery, unanticipated hospital admissions after ambulatory procedures, wound dehiscence, electrolyte disturbances, and increased healthcare costs. Among the pharmacologic strategies available for prophylaxis for PONV, dexamethasone is widely used due to its efficacy, favorable safety profile in single-dose use, and cost-effectiveness.
Dexamethasone, a long-acting corticosteroid with potent anti-inflammatory properties, is typically administered intravenously at induction of anesthesia in doses ranging from 4 mg to 8 mg in adults. Although its precise antiemetic mechanism remains incompletely elucidated, several pathways have been proposed. These include inhibition of prostaglandin synthesis, reduction of serotonin release in the gut, modulation of the nucleus tractus solitarius, and attenuation of surgical inflammatory responses that may trigger emetic pathways. The delayed onset of its antiemetic effect compared with 5-HT3 antagonists supports administration at induction rather than at the end of surgery.
Multiple randomized controlled trials and meta-analyses have demonstrated that dexamethasone significantly reduces the incidence of early and late PONV compared with placebo. Its effect appears particularly robust in reducing postoperative vomiting, though meaningful reductions in nausea have also been documented. When used as monotherapy in moderate-risk patients, dexamethasone provides a relative risk reduction comparable to that of ondansetron. However, its greatest benefit is observed in combination regimens. Current consensus guidelines recommend multimodal prophylaxis for patients with multiple risk factors, and dexamethasone is frequently combined with a 5-HT3 receptor antagonist, droperidol, or neurokinin-1 receptor antagonists. Additive and sometimes synergistic reductions in PONV incidence have been observed with these combinations, without a proportional increase in adverse effects.
Beyond antiemetic efficacy, dexamethasone administration has been associated with ancillary benefits relevant to perioperative care. These include reduced postoperative pain scores and decreased opioid consumption, likely mediated through attenuation of inflammatory cascades. Reduced opioid requirements may indirectly further lower PONV risk. In certain surgical populations, including those undergoing thyroidectomy or laparoscopic procedures, dexamethasone has also been associated with improved early recovery parameters and shorter time to discharge readiness.
Safety considerations remain central to corticosteroid use. In the context of single perioperative dosing, adverse effects are generally minimal. Transient hyperglycemia is the most consistently observed effect, particularly in patients with diabetes mellitus. While elevations in serum glucose can be clinically significant, especially in poorly controlled diabetics, they are typically self-limited. Concerns regarding impaired wound healing and increased risk of surgical site infection have not been substantiated in the majority of studies evaluating single-dose administration. Nonetheless, perioperative glucose monitoring is prudent, especially in high-risk populations.
Optimal dosing when administering dexamethasone for PONV prevention remains a subject of ongoing research. Evidence suggests that 4 mg may suffice for antiemetic prophylaxis in lower-risk patients, while 8 mg may confer greater efficacy in higher-risk groups without substantially increasing adverse events. Doses above 8 mg have not consistently demonstrated additional benefit in PONV prevention and may increase the likelihood of hyperglycemia.
Dexamethasone represents an effective and well-validated component of PONV prophylaxis strategies. Its benefits extend beyond reduction of nausea and vomiting to include potential analgesic and opioid-sparing effects. When administered as a single perioperative dose, it demonstrates a favorable safety profile, with transient hyperglycemia as the principal consideration.