The Worthing-based agency will manage national campaigns and all press office activity. Pegasus has taken the business from London agency Schwartz and will use five of its 35 staff to service the account.
Pegasus will start with a campaign to highlight Sk:n, which has 36 outlets in the UK, as one of the largest network of clinics to be approved by the Independent Healthcare Advisory Services' new register.
The IHAS Register of Injectable Cosmetic Providers vets and registers a quality assurance mark approval for regulated healthcare professionals, organisations and facilities involved with injectable cosmetics.
The register reflects growing concerns over people receiving botched treatments in inappropriate settings. Those signing up to the register must ensure procedures take place in a clean and safe clinical setting and registered premises may be inspected at random by an outside agency. They must also promise that prospective clients receive a face-to-face consultation before any treatment goes ahead.
The five-figure contract follows a high-profile sun awareness project for the company this summer, when Pegasus used the England cricket team to promote Sk:n's £1 'Face Facts' facial skin assessment.
Helen Yeardsley, director at Pegasus, said: 'We knew when we did the Face Facts campaign that the firm was looking for a new retained agency.' She said Pegasus would aim to 'deliver messages about science, as well as celebrity-based campaigns'.