Comparison 4. Analysis excluding the studies with many unclear risk of bias characteristics (Principi 1986).

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Clinical cure rate at the end of therapy	4	1491	Risk Ratio (M‐H, Fixed, 95% CI)	1.03 [0.99, 1.07]
2 Clinical cure rate during therapy	3	1381	Risk Ratio (M‐H, Fixed, 95% CI)	1.04 [0.98, 1.10]
3 AOM complications: Recurrent AOM after completion of therapy	2	929	Risk Ratio (M‐H, Random, 95% CI)	1.01 [0.39, 2.60]
4 Adverse reactions to medication: Overall adverse events	2	878	Risk Ratio (M‐H, Random, 95% CI)	0.92 [0.52, 1.63]
5 Specific adverse reactions to medication: Diarrhoea	3	1453	Risk Ratio (M‐H, Fixed, 95% CI)	0.70 [0.48, 1.00]
6 Specific adverse events to medication: Skin adverse events	2	990	Risk Ratio (M‐H, Fixed, 95% CI)	0.72 [0.44, 1.17]