Generally, people who have mild acne can be treated with topical treatments, and those with moderate acne through a combination of topical and systemic treatments such as isotretinoin, says David Pariser, dermatology professor at Eastern Virginia Medical School in Norfolk and principal investigator of clinical trials with Oslo-based specialty drug maker Photocure, which is developing a photodynamic treatment for moderate-to-severe acne.

WSJ: As More Adults Get Acne, New Photodynmic Treatments Use Light