Three depths, three different procedures
This is the distinction that everything else follows from, and quotes often blur it deliberately.
Superficial peels. Alpha hydroxy acids such as glycolic and lactic acid, beta hydroxy acid such as salicylic, and low-concentration trichloroacetic acid. They reach the outermost layer of the skin. They brighten, improve mild texture and help acne and congestion. Recovery is redness for a few hours and light flaking for two to five days, and makeup is usually possible the next day. They work as a course of four to six treatments two to four weeks apart, and the effect is gradual. This is the safest option in any skin type and the sensible starting point for most people.
Medium peels. Trichloroacetic acid at higher concentration, sometimes combined with other agents, or the classic Jessner's solution followed by trichloroacetic acid. They reach into the upper dermis. They treat fine lines, sun damage, pigmentation and superficial scarring meaningfully. Recovery is significant: the skin darkens, tightens and then peels in sheets over five to ten days, with about a week before you are presentable and pinkness for two to six weeks. One treatment gives a real result, and it can be repeated after some months.
Deep peels. Phenol, usually as a Baker-Gordon formula, sometimes in modified versions. They reach the mid dermis. They produce the most dramatic improvement available for deep perioral wrinkling and severe sun damage, comparable to or exceeding fully ablative laser. They are a medical procedure: sedation or general anaesthesia, cardiac monitoring because phenol is absorbed and can affect heart rhythm, intravenous fluids, and a recovery of two weeks of dressings with redness for three months or more. They also very commonly lighten the treated skin permanently, which produces a demarcation line at the jaw unless the whole face is treated, and they are unsuitable for most skin types beyond the fairest.
Combinations and segmental treatment. A deep peel applied only around the mouth, where the deepest wrinkles are, with a medium peel elsewhere, is a recognised approach.
What the marketing obscures. Names of proprietary peels tell you nothing. What tells you something is the acid, the concentration, and the intended depth. A clinic that will not state those is selling a brand.
What to ask. Which acid, at what concentration, reaching which depth, and how many days of visible peeling? Then match that against how long you are in the country and what you can hide.
