Bayer has called in around six agencies to pitch, although it is unclear if the review encompasses all UK brands.
In the over-the-counter medicine market, Bayer owns brands including the digestive remedy Alka Seltzer, the analgesic Aspirin, the anti-fungal brand Canesten and the insect repellent Autan.
Its rival, Pfizer, is currently running a global advertising review out of New York to consolidate its agency roster.
Moves in the pharmaceutical industry come as drug giants look to take advantage of advertising opportunities that have arisen from prescription drugs now being available as over-the-counter medicine. The Government has put in motion plans to shift the regulations on prescription-only products that will dramatically increase the number of products available over the counter. Products including the hayfever remedy Claritin, Regaine and the cold sore cream Zovirax used to be prescription-only, but are now marketed to consumers.
No-one at either Bayer or AMV was available to comment as Campaign went to press.