RB has consolidated its global vitamins, minerals and supplements advertising business into McCann Worldgroup.
The decision will see the move of accounts to promote brands such as MegaRed and Airborne, previously handled by KWG in America and Havas Worldwide elsewhere around the world.
McCann Worldgroup was appointed earlier this year, alongside Droga5 and Wieden + Kennedy to the new creative agency roster alongside Havas Worldwide.
RB brands such as Mucinex and Delsym are already handled by McCanns for RB globally, with this decision to move accounts made following its previous work with those brands, the company has explained.
The most recent work for Mucinex went live in October.