They can cost just a couple of pounds - but it's estimated many schoolgirls are missing out on their education because of the price of sanitary products.
A charity called the Red Box Project says there is still a stigma around menstruation and more needs to be done change attitudes.
So-called 'Red Boxes' - where girls can collect items for free - have been set-up across the South including Andover, Worthing, Wokingham, Swanage, Aylesbury and at the Oxford Academy School. Rachel Pritchard reports.
Click hereto find out where Red Boxes are located.