Efficacy of prophylactic dexamethasone in preventing opioid-induced nausea and vomiting in cancer patients: A randomized controlled trial.

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Background: Opioid initiation for cancer pain is frequently complicated by nausea and vomiting, impairing adherence and delaying dose optimisation. Evidence supporting routine prophylactic antiemetic use during oral morphine initiation remains limited. We evaluated whether a single pre-emptive dose of dexamethasone reduces early opioid-induced nausea and vomiting (OINV). Methods: In this single-centre, open-label, randomized controlled trial , 150 adult cancer patients initiating oral morphine were randomized 1:1 to receive oral dexamethasone 8 mg administered 6 hours prior to morphine or standard care without prophylaxis. The primary endpoint was nausea severity assessed using a Numerical Rating Scale (NRS 0–10). Secondary endpoints included vomiting frequency and rescue antiemetic use assessed on Days 1, 3, and 5. Analyses were conducted on an intention-to-treat basis. Results: A total of 150 patients were randomized (dexamethasone n=74; control n=76). On Day 1, mean nausea scores were significantly lower in the dexamethasone group compared with control (1.86 vs 2.93; mean difference −1.07; p=0.01). The difference remained significant on Day 3 (1.45 vs 2.59; mean difference −1.14; p=0.02) but was not significant by Day 5 (p=0.18). Mean vomiting episodes were reduced on Day 1 (0.45 vs 1.29; mean difference −0.84; p=0.01). Change-from-baseline analysis demonstrated greater reduction in nausea at Day 3 (−0.93 ± 1.22 vs −0.34 ± 1.16; p=0.03) and vomiting frequency (−0.72 ± 1.25 vs −0.04 ± 0.65; p=0.01) in the dexamethasone arm. Differences in vomiting frequency at later time points were not statistically significant. No steroid-related serious adverse events were reported. Conclusions: In this open-label randomized trial, a single prophylactic dose of dexamethasone was associated with significant reduction in early opioid-induced nausea and vomiting during morphine initiation without additional toxicity. Prophylactic dexamethasone may represent a simple and cost-effective strategy to improve opioid tolerability in oncology practice, particularly in resource-limited settings. Clinical trial information: CTRI/2026/02/104005 .

Clinical outcomes during opioid initiation.