BACKGROUND The dermis is composed primarily of type I (soft) and type III (rigid scar-like) collagen. Collagen degradation is considered the primary cause of skin aging. Studies have proved the efficacy of infrared irradiation on collagen stimulation but have not investigated the differential long-term effects of infrared irradiation on type I and type III collagen.

OBJECTIVE To determine differential long-term stimulation of type I and type III collagen after infrared (1,100–1,800 nm) irradiation.

METHODS AND MATERIALS In vivo rat tissue was irradiated using the infrared device. Histology samples were analyzed for type I and III collagen stimulation, visual changes from baseline, and treatment safety up to 90 days post-treatment.

RESULTS Infrared irradiation provided long-term stimulation of type I collagen and temporary stimulation of type III collagen. Treatment also created long-term smoothing of the epidermis, with no observed complications.

CONCLUSIONS Infrared irradiation provides safe, consistent, long-term stimulation of type I collagen but only short-term stimulation in the more rigid type III collagen. This is preferential for cosmetic patients looking for improvement in laxity and wrinkles while seeking smoother, more youthful skin.