Comparison 1. Treatment versus control (headache) post‐treatment.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1.1 Pain	15	644	Risk Ratio (M‐H, Random, 95% CI)	2.35 [1.67, 3.30]
1.1.1 N < 20	13	437	Risk Ratio (M‐H, Random, 95% CI)	2.86 [1.73, 4.72]
1.1.2 N > 20	2	207	Risk Ratio (M‐H, Random, 95% CI)	1.88 [1.36, 2.58]
1.2 Disability	6	446	Std. Mean Difference (IV, Random, 95% CI)	‐0.26 [‐0.56, 0.03]
1.2.1 N < 20	2	61	Std. Mean Difference (IV, Random, 95% CI)	0.04 [‐0.47, 0.54]
1.2.2 N > 20	4	385	Std. Mean Difference (IV, Random, 95% CI)	‐0.35 [‐0.69, ‐0.00]
1.3 Depression	6	400	Std. Mean Difference (IV, Random, 95% CI)	‐0.08 [‐0.28, 0.11]
1.3.1 N < 20	3	103	Std. Mean Difference (IV, Random, 95% CI)	‐0.16 [‐0.68, 0.35]
1.3.2 N > 20	3	297	Std. Mean Difference (IV, Random, 95% CI)	‐0.06 [‐0.29, 0.17]
1.4 Anxiety	7	439	Std. Mean Difference (IV, Random, 95% CI)	‐0.11 [‐0.39, 0.17]
1.4.1 N < 20	4	136	Std. Mean Difference (IV, Random, 95% CI)	0.01 [‐0.54, 0.57]
1.4.2 N > 20	3	303	Std. Mean Difference (IV, Random, 95% CI)	‐0.19 [‐0.49, 0.11]