Study	No. of participants	Ginger dosage (form)	Comparator	Effect on nausea scores	Effect on vomiting frequency
Four-day, double-blind RCT2	120	125 mg four times per day (liquid extract)*	Placebo (pure soy oil)	Less nausea with ginger three days out of four†	No change
Four-day, double-blind RCT3	70	250 mg four times per day (powder capsules)	Placebo	63 percent decrease with ginger versus 42 percent decrease with placebo (P = .014)	47 percent decrease with ginger versus 25 percent decrease with placebo (P < .001)
Four-day, single-blind RCT4	67	250 mg four times per day (powder capsules)	Placebo	85 percent decrease with ginger versus 56 percent decrease with placebo‡ (P < .01)	50 percent decrease with ginger versus 9 percent decrease with placebo (P < .05)
Fourteen-day, double-blind RCT5	26	250 mg four times per day (syrup in water)§	Placebo (with lemon oil)	77 percent decrease with ginger versus 20 percent decrease with placebo∥	By day 6, vomiting resolved in 67 percent of the ginger group versus 20 percent of the placebo group∥
Seven-day, double-blind RCT6	170	500 mg twice per day (powder capsules)	Dimenhydrinate (50 mg twice per day)	No change	10 to 20 percent less in the dimenhydrinate group on days 1 to 2 (P < .05), but no difference on days 3 through 7¶
Meta-analysis of RCTs up to 21 days1	251	975 to 1,500 mg per day (various)	Pyridoxine (30 to 75 mg per day)	No difference in combined nausea and vomiting scores at day 3 (standard mean difference = 0.0; 95% confidence interval, –0.25 to 0.25)