The review is being run across the pharmaceutical and over-the-counter medicine division of GSK. Other brands within the division include Zovirax, Day Nurse and Panadol.
The review is being handled by GSK's procurement, commercial and general department and its web design sourcing group.
GSK uses a large number of digital agencies - from the digital arms of above-the-line roster agencies such as Grey Interactive to smaller shops for bespoke project work.
It is understood the wide-ranging review is part of a move by GSK to tighten its new-media and digital strategy to look at forming a preferred supplier list.
Its above-the-line roster agency Ogilvy & Mather recently lost its most senior GSK handler. John O'Shea, a managing partner and worldwide account director, was poached by Leo Burnett to head its office in Singapore.
Late last year, GSK examined its above-the-line agency relationships in the UK and called a pitch for its Lucozade Sport account, held by O&M.
Last month, the agency lost its 12-year grip on the £7 million business when M&C Saatchi was appointed.
However, O&M continues to hold the Lucozade Energy account and other GSK brands around the world.