Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Headache duration, frequency, or intensity
[25] RCT Crossover design	24 people (diagnosed with IHS criteria[17])	Headache frequency (days with headache) last 4 weeks of treatment 25.5 with high-dose mirtazapine 28.0 with placebo	P = 0.005 The RCT did not report results before crossover, so results should be interpreted with caution	Effect size not calculated	mirtazapine
[25] RCT Crossover design	24 people (diagnosed with IHS criteria[17])	Headache duration (hours with headache) last 4 weeks of treatment 210 with high-dose mirtazapine 288 with placebo	P = 0.03 The RCT did not report results before crossover, so results should be interpreted with caution	Effect size not calculated	mirtazapine
[25] RCT Crossover design	24 people (diagnosed with IHS criteria[17])	Headache intensity (verbal rating scale 0–10) last 4 weeks of treatment 4.2 with high-dose mirtazapine 4.3 with placebo	P = 0.03 The RCT did not report results before crossover, so results should be interpreted with caution	Effect size not calculated	mirtazapine
[23] RCT 4-armed trial	93 people (diagnosed with IHS criteria[17])	Headache frequency (change from baseline in days with headache) last 4 weeks of treatment 28–28 with low-dose mirtazapine 28–28 with placebo	Reported as not significant P value not reported		Not significant
[23] RCT 4-armed trial	93 people (diagnosed with IHS criteria[17])	Headache duration (change from baseline in hours with headache) last 4 weeks of treatment 408–290 with low-dose mirtazapine 371–334 with placebo	Reported as not significant P value not reported		Not significant
[23] RCT 4-armed trial	93 people (diagnosed with IHS criteria[17])	Headache intensity (change from baseline in 11-point verbal rating scale, from 0 = headache free to 10 = worst headache imaginable) last 4 weeks of treatment 4.5–4.1 with low-dose mirtazapine 5.0–4.4 with placebo	Reported as not significant P value not reported		Not significant