The Science Behind Chemical Peels

A chemical peel, at its most fundamental level, is a controlled injury to the skin. By applying an acid solution that disrupts the bonds between dead skin cells, the treatment encourages accelerated cell turnover, collagen synthesis, and the removal of damaged surface layers. The result, when performed correctly, is smoother, brighter, and more evenly toned skin.

The most commonly used acids in professional peels fall into two main families: alpha-hydroxy acids (AHAs) and beta-hydroxy acids (BHAs). AHAs — which include glycolic acid, lactic acid, and mandelic acid — are water-soluble and work primarily on the surface of the skin. They are excellent for addressing fine lines, uneven texture, and hyperpigmentation. BHAs, the most well-known being salicylic acid, are oil-soluble and can penetrate into the pore lining, making them particularly effective for acne-prone and congested skin.

Peel depth is classified into three categories: superficial, medium, and deep. Superficial peels, which use low concentrations of AHAs or BHAs, only affect the outermost layer of the epidermis. They cause minimal visible peeling and require no downtime, making them suitable for monthly treatments. Medium-depth peels — typically using trichloroacetic acid (TCA) at concentrations of 20–50% — penetrate into the dermis and produce more significant peeling over 5–7 days, with greater improvements in wrinkles and pigmentation. Deep peels, such as phenol peels, affect the mid-dermis and require careful medical supervision, significant downtime, and are typically only performed once.

For most clients at a professional skincare clinic, superficial to medium peels make up the vast majority of treatments. A series of 4–6 superficial peels spaced 3–4 weeks apart is a widely recommended approach for skin rejuvenation, allowing the skin to recover fully between sessions while building cumulative improvement.

Post-peel care is critical to results. Sun protection is non-negotiable — the new skin revealed by a peel is significantly more photosensitive than your usual skin, and UV exposure in the days following a peel can cause new hyperpigmentation to form. A broad-spectrum SPF 50 applied daily, alongside a gentle moisturiser and temporary avoidance of active ingredients like retinol and vitamin C, gives the skin the best environment to heal and reveal its full potential.