The retailer currently spends £6 million a year on advertising, according to The Nielsen Company, but is expected to increase its spend to £15 million as it takes on the market leader, Boots.
The company, which previously managed its advertising in-house, appointed HMDG after a four-way pitch and is planning a major TV campaign in the run-up to Christmas.
The retailer's most recent retained agency was Euro RSCG, which was appointed to handle branding work in May 2005. Superdrug, owned by the retail group AS Watson, parted company with the agency the following December as it switched its focus from TV to press ads.
HMDG's first Superdrug campaign, which will run on terrestrial TV channels, will highlight the retailer's value proposition.
Superdrug's media planning and buying, which is handled by ZenithOptimedia, is unaffected by the review.
Steve Jebson, the commercial director at Superdrug, said: "We are clear on our strategy, our purpose and branding and we are ready to go out and start talking to our customers."
He added: "We want people to take another look at Superdrug and hopefully reassess some of the perceptions they might have had."