Table 1.

Characteristics of the included randomized controlled trials and two incompletely reported trials

References	Number of participants	Age (yr)	Setting (country)	Treatment	Comparison	Follow up	Dropouts
de Mey et al. 2008 [15]	92	n.r.*	outpatients (n.r)	Ambroxol 5, 10, 20 mg	Placebo	1 day	11
Schutz et al. 2002,[14]	215	39,4 ± 15	outpatients (Germany)	Ambroxol 20 mg	Placebo	2 days	19
Fischer et al. 2002 [16]	331	37 ± 13	outpatients (RSA)	Ambroxol 20, 30 mg	Placebo	3 days	48
Fischer et al. 2002 [16]	383	36 ± 12	outpatients (RSA)	Ambroxol 20, 30 mg	Placebo	3 days	58
de Mey et al. 2008 [15]	751	n.r.*	outpatients (n.r.)	Ambroxol 20, 3 mg benzocaine**	Placebo	3 days	27
Registered trials with incompletely reported results
clinicaltrials.gov 2006	221	n.r.	outpatients (RSA)	Ambroxol 20 mg	Placebo	3 days	0
clinicaltrials.gov 2008	259	n.r.	outpatients (China)	Ambroxol 20 mg	Placebo	n.r.	0

n.r. = not reported, RSA = Republic of South Africa, * inclusion age was 16 to 80 years, but average age for those trials was not reported **the outcome of the benzocaine treatment arm is not reported.