Chemical peel is one of the oldest rejuvenating methods currently in use. Despite the proliferation of alternatives, such as laser resurfacing or dermabrasion, chemical peels remain widely used because they are relatively inexpensive and their short and long-terms effects are well understood. Also, many practitioners have much more experience with peels than with the newer procedures.
Chemical peels are based on a very simple idea. A solution of a chemical agent is applied to the skin and the agent’s reaction with the skin causes superficial damage and peeling. Mild peeling solutions only loosen and remove stratum corneum (the upper part of the epidermis consisting of dead cells), while the stronger ones can affect the entire epidermis and even the upper dermis. Hence, chemical peels are classified as light (superficial), medium and deep. The deeper the peel, the greater is the potential for both cosmetic improvement and side effects.
Superficial peels are the mildest of the chemical peels and are mainly used to improve skin texture and reduce roughness. They mainly remove stratum coneum (dead skin surface cells) and sometimes the upper epidermis. They might improve discolorations, especially if the peeling solution includes a bleaching agent. Some types of superficial peels (such as salicylic acid peel) may help improve acne but that is not well researched.
Superficial peels are generally repeated at regular intervals to maintain results. Improvements with superficial peels are usually short-lived – hence superficial peels are often used repeatedly. Some people get cumulative improvement with repeated superficial peels; others simply maintain initial improvement; yet others see little or no improvement.
Superficial peels require no downtime but it is common to have a brief period of redness, flaking and/or skin sensitivity after a peel. However, peels should not be repeated so often as to create a state of chronic skin irritation and hypersensitivity. Otherwise, your skin will actually end up aging faster.
The most common agents used for superficial peels are alpha hydroxy acids (e.g. glycolic acid, lactic acid) and beta hydroxy acids (salicylic acid). Sometimes additional bleeching agents (e.g. hydroquinone, kojic acid) or other modifiers are added to customize the effects.
Superficial peels, such as 30% alpha or beta hydroxy acid peels, are not considered medical procedures by the FDA and are often performed by estheticians rather than doctors.
Medium peels impact the epidermis and upper dermis. The damage caused by the peeling agent induces a healing response and leads to a mild-to-moderate skin remodeling. As a result, medium chemical peel usually improves not only skin texture, but also fine lines and small wrinkles. Deeper wrinkles remain mostly unaffected. Blemishes and discolorations may also improve.
Medium peels may needed to be repeated two or more times to obtain the desired result. They would usually be spaced out over several months.
The most common agent for medium peels is trichloroacetic acid (TCA). It is a medium-strength acid, which produces damage by breaking up connections between cells, denaturing proteins in cells and skin matrix and so forth. After TCA treatment the skin surface becomes crusty and mild-to-moderate swelling would generally develop. You will need about 7-10 days of downtime to heal sufficiently to return to work and other normal activities. It is best to avoid sun exposure or at least use heavy UVA+UVB protection for at least a few more weeks. The improvements after medium peel are more lasting compared to superficial peel but fall short of the results delivered by deep peels.
Deep peels affect both epidermis and dermis and are both more effective and more risky than superficial or medium peels. It is mainly used to improve medium-to-deep wrinkles, severe skin roughness and other advanced signs of skin aging. The most common agent used in deep peels is phenol, which produces tissue necrosis by denaturing biological polymers.
Some call deep chemical peel a poor man’s laser resurfacing. This is inaccurate because deep peels are not that much cheaper than ablative resurfacing. However, the degree of skin ablation, typical results, downtime and side effects of a deep peel are comparable to those of ablative laser resurfacing.