Table 1.

Prevalence of adverse events reports by type of social media and denominator

Social media	Percentage of adverse event posts from all posts	Percentage of adverse event posts from posts related to intervention/illness
Facebook	4% (n = 1)	0.7%–2% (n = 2)
Blogs, Facebook, Twitter and forums	0.3%–8% (n = 2)
Twitter	2%–4% (n = 1)	0.02%–11.5% (n = 3)
General forums	0.2%–1.42% (n = 4)	18.2%–35% (n = 4)
General and disease specific forums		12%–58% (n = 3)
Disease specific forums		12%–62% (n = 4)
Disease specific forums and blogs		12.4% (n = 1)
YouTube		40%–78% (n = 3)

n = number of studies

NB. Some studies measured more than one value contained in the above table