1. Adverse events.

Study	Intervention (N experiencing event)	Control (N)	Comments
Brouillette 2001	0	nose bleed (1)
Goldbart 2012	0	0
Chan 2015	nasal bleeding (3), nasal discomfort (1), throat discomfort (1), vomiting (1)	nasal bleeding (3), nasal discomfort (1), diarrhoea (1)	Total number of adverse events reported (10) does not match sum of individual adverse events (11)
Kheirandish‐Gozal 2016	headache (1), nausea (1)	headache (1), nausea (2)

Since Kheirandish‐Gozal 2008 did not analyse and report their data as randomised, we did not consider this trial in the analysis.