Date	Event	Description
10 December 2014	Review declared as stable	This review will be assessed for further updating in 2024.
22 October 2014	New search has been performed	We ran new searches on 28 August 2014. No new studies for inclusion or exclusion, but identified five additional unpublished studies. We used a slightly different approach to outcomes from some headache studies, and corrected some minor errors.
22 October 2014	New citation required but conclusions have not changed	Conclusions unchanged. PRISMA flow chart and 'Summary of findings' table added
27 June 2012	Amended	Contact details updated.
16 April 2012	Amended	Minor correction to forest plot of Analysis 3.1.