Light-activated antimicrobial devices and articles are disclosed. The devices include a light source and a light-activated antimicrobial article comprising a photosensitizer and a viscoelastic material such as a pressure sensitive adhesive adapted to receive light from the light source. The viscoelastic material may be adapted to transport light by total internal reflection. The photosensitizer may comprise a dye, a metal oxide or a composition that comprises anions that oxidize or react to form a gas. Upon activation of the light source, the photosensitizer absorbs light from the light source such that antimicrobial activity is exhibited. The photosensitizer may be included in the light-activated antimicrobial article or it may be provided as a topical composition that is separate from the article. The light-activated antimicrobial articles and devices may have constructions similar to those of wound dressings.