Table 1.

Characteristics of the included studies.

Study	Design	Disease	Age (Range, years)	Therapy in experimental group	Therapy in control group	Dosage	Sample size		NEa sample size		NEa type and sample size	Follow up period (wk)
							Experimental	Control	Experimental	Control
Leff 1998	RCTb	asthma	15–45 years	Montelukast	Placebo	10 mg	54	56	11	18	Headache11/18	12
Knorr 1998	RCTb	asthma	6- 14-years	Montelukast	Placebo	5 mg	201	135	38	29	Headache38/29	8
Noonan 1998	RCTb	asthma	18–65 years	Montelukast	Placebo	2mg/10mg/50 mg	212	69	18	10	Headache18/10	3
Reiss 1998	RCTb	asthma	≥15 years	Montelukast	Placebo	10 mg	408	273	75	61	Headache73/57; depression1/4; anxiety1/0	12
Malmstrom 1999	RCTb	asthma	≥15 years	Montelukast	Placebo	10 mg	387	257	68	40	Headache68/40	12
Meltzer 2000–1	RCTb	Allergic rhinitis	15–75 years	Montelukast	Placebo	10 mg	185	91	12	6	Headache12/6	2
Meltzer 2000–2	RCTb	Allergic rhinitis	15–75 years	Montelukast/Loratadine	Loratadine	10 mg + 10 mg:10 mg	90	92	1	8	Headache1/8	2
Nayak 2002–1	RCTb	Allergic rhinitis	15–85 years	Montelukast	placebo	10 mg	155	149	5	7	Headache5/7	2
Nayak 2002–2	RCTb	Allergic rhinitis	15–85 years	Montelukast/Loratadine	Loratadine	10 mg + 10 mg:10 mg	302	301	9	12	Headache9/12	2
Baumgartner 2003	RCTb	asthma	≥15 years	Montelukast	Placebo	10 mg	313	103	31	18	Headache31/18	6
Baena-Cagnani 2003	RCTb	Allergic rhinitis and asthma	≥15 years	Montelukast	Placebo	10 mg	311	302	11	11	Headache11/11	4
Yildirim 2004	RCTb	asthma	mean:36.93 ± 2.98 years	Montelukast/Budesonide	Budesonide	10 mg + 400 mg:800 mg	15	15	2	0	Headache2/0	6
Asthma linical Research enters 2007	RCTb	asthma	≥15 years	Montelukast	Placebo	10 mg	164	164	34	36	nervousness34/36	24
Shah 2006	RCTb	asthma	18–60 years	Montelukast/Budesonide	Budesonide	10 mg + 200 mg:400 mg	30	30	1	0	Headache1/0	8
Bisgaard 2009	RCTb	Allergic rhinitis	2–14 years	Montelukast	Placebo	5 mg	280	133	9	2	Headache9/2	8
Chen 2021	RCTb	Allergic rhinitis	18–60 years	Montelukast/Budesonide	Budesonide	10 mg + 256ug:256ug	23	23	0	0	No	2
Prenner 2010–1	RCTb	asthma	15–92 years	Montelukast	Placebo	10 mg or 20 mg	555	1111	6	19	Headache6/19	2
Prenner 2010–2	RCTb	asthma	15–92 years	Montelukast/Loratadine	Loratadine	10 mg + 10 mg:10 mg	969	971	66	85	Nervous system disorders66/85; Headache34/29; Somnolence25/10	2

^aNE: Neuropsychiatric event.

^bRCT: randomized controlled trial.