Chemical peels: depths, downtime, risks and the sun

A chemical peel is one of the oldest treatments in skin medicine, and still one of the most useful when it is well chosen. The key word is depth. A gentle glycolic peel and a deep peel share a name, but very little else. Here is how they differ, what each can and cannot do, and how to time a peel when you live with the Costa del Sol sun.

What a chemical peel is

A peel is an acid solution applied to the skin for a set time. It loosens and removes the outer layers in a controlled way. The skin then repairs itself, and the new surface is smoother and more even.

Peels are grouped by how deep they reach. That depth is directly linked both to how much improvement you can expect and to how many complications can occur ^[1]. Choosing the depth is the most important decision, and it should be made by looking at your skin.

Superficial, medium and deep peels

Superficial peels act on the outermost layer of the skin. They are the ones most people mean when they ask about a peel:

• Glycolic acid, an alpha hydroxy acid with small molecules. It is the classic choice for dull skin, uneven texture and mild pigmentation. A glycolic peel can be made gentler or stronger by changing the concentration and contact time.
• Salicylic acid, a beta hydroxy acid that dissolves in oil. It reaches inside the pore, which is why it suits oily skin, blackheads and acne.
• Mandelic acid, a larger, slower molecule, often chosen for reactive skin. It is also used together with salicylic acid for acne.
• Lactic acid, a mild acid often used for dry or sensitive skin.

Medium-depth peels, usually based on trichloroacetic acid, reach the upper part of the dermis, the layer beneath the surface. They are used for more marked sun damage, fine wrinkles and some pigmentation.

Deep peels reach further into the dermis. The older formulas left the skin very pale and were largely abandoned. Modern versions use lower concentrations, have a better safety profile and aim for subtler, more natural tightening and wrinkle improvement ^[2]. Even so, they remain a medical procedure with careful preparation and weeks of recovery.

What each depth can treat

Dullness and texture. Superficial peels give a fresher, brighter surface. This is where most people start.

Acne. A systematic review of 12 randomised trials with 387 participants found that the common peels, including glycolic and salicylic acid, worked similarly for mild to moderate acne and were well tolerated ^[3]. Glycolic acid did better than placebo. In one trial, a combined salicylic and mandelic peel did better than glycolic acid alone. The authors note that the trials were of very low to moderate quality, so no peel can be called the clear winner.

Pigmentation and melasma. A 2024 systematic review of 24 studies with 1,075 patients found peels safe and effective for melasma, with glycolic acid performing well ^[4]. Melasma is a chronic condition that tends to come back, so a peel is one part of a longer plan, not a cure. Our guide to melasma explains the wider picture.

Sun spots. For the flat brown spots caused by years of sun, the evidence favours other tools. In a review of 41 trials, peels with trichloroacetic acid cleared lesions in 12% to 46% of cases, while intense pulsed light reached 74.6% to 90% ^[8]. If sun spots are your main concern, read about IPL for sun spots and pigmentation.

Fine lines and sun damage. A 2026 meta-analysis of 38 studies with 1,695 patients compared peels with laser resurfacing. Overall results were comparable, and pigment marks after treatment were similarly common. Lasers needed, on average, two fewer sessions, but caused more redness and discomfort ^[6].

Acne scarring. A 2026 meta-analysis of 11 studies with 713 participants found peels and microneedling broadly comparable for depressed acne scars, with no clear advantage for either ^[5]. Deep scars often need a combination of techniques.