A chemical peel is a treatment in which one or more chemical exfoliating/irritating agents are applied to the skin; they interact with the cellular and dermal layers, causing selective and controlled damage to the skin.

In the epidermis the chemical agents reduce cohesion or cause thinning of the keratinocytes. This results in:

• removal of the cornified layer of the skin, and the keratin plugs of open comedos or blackheads
• increased cellular turnover and exfoliation
• inhibition of sebaceous gland activity

In the dermis the chemical agents:

• have an irritating effect with consequent erythema and edema
• stimulate the fibroblasts to produce glycoproteins and new collagen, restructuring the extracellular matrix

They can be classified as follows:

• very superficial: only the superficial epidermis is exfoliated
• superficial: necrosis of part or all of the epidermis down to the basal layer
• middle: necrosis of the epidermis and part or all of the papillary dermis
• deep: necrosis of the epidermis down to the reticular dermis

The most commonly used peels are: glycolic acid, mandelic acid, pyruvic acid, trichloroacetic acid, lactic acid, azelaic acid, retinoic acid, phytic acid, salicylic acid, resorcinol and phenol. Today a combination of these is preferred, such as Jessner’s solution, blue peel or yellow peel.