Comparison 1. Dopamine receptor antagonists versus placebo.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1.1 Vomiting	3	527	Risk Ratio (M‐H, Random, 95% CI)	1.18 [0.26, 5.32]
1.2 Nausea	2	336	Risk Ratio (M‐H, Random, 95% CI)	0.55 [0.15, 2.03]
1.3 Adverse events	3	527	Risk Ratio (M‐H, Random, 95% CI)	2.34 [0.47, 11.61]
1.4 Adverse events (extrapyramidal symptoms)	3	527	Risk Ratio (M‐H, Random, 95% CI)	2.81 [0.12, 67.71]
1.5 Adverse events (sedation/drowsiness)	3	527	Risk Ratio (M‐H, Random, 95% CI)	2.81 [0.12, 67.71]
1.6 Adverse events (vertigo/dizziness)	3	527	Risk Ratio (M‐H, Random, 95% CI)	4.69 [0.23, 95.66]
1.7 Adverse events (other)	3	527	Risk Ratio (M‐H, Random, 95% CI)	0.47 [0.04, 5.03]
1.8 Nausea severity	1	191	Mean Difference (IV, Random, 95% CI)	‐0.49 [‐0.75, ‐0.23]
1.9 Rescue medication	3	527	Risk Ratio (M‐H, Random, 95% CI)	1.86 [0.17, 20.16]