The account was put up for review following Bayer's purchase of the over-the-counter division of Roche. PHD was the incumbent on the former and MediaCom on the latter.
The $2.9 billion purchase of Roche's OTC division has made Bayer one of the biggest consumer health organisations in the world. Its brands include Alka-Seltzer, Rennie and Berocca.
Bayer and Roche's creative accounts, held by Abbott Mead Vickers BBDO and JWT, were unaffected.
Separately, PHD has also won the £33 million media planning account for the AA after a head-to-head battle against MindShare. The review was overseen by Kerry Cooper, the director of AA road sales and marketing, with assistance from the media auditor Billetts. The incumbent, Manning Gott-lieb OMD, pulled out of the review, leaving MindShare and PHD to fight it out.
The AA called an ad review at the end of last year as part of a wider business review by its new owners, the venture capitalists CVC and Permira.
PHD will work alongside Delaney Lund Knox Warren & Partners, which was appointed last week to AA's loans, insurance and roadside businesses.