Studies on the effects of topical retinoic acid on photoageing.

Tretinoin has been previously shown in animal and clinical studies to stimulate epidermal cell production and to be effective in the treatment of solar keratoses. A double-blind, placebo-controlled study confirmed that topical tretinoin produced an overall improvement in photoaged skin and decreased solar keratoses. There is no evidence that tretinoin has an irritative effect, nor is there any evidence that the improvement in appearance is due to oedema.