Facial peel: understanding chemical exfoliation

A facial peel is an exfoliation that acts chemically rather than mechanically. Where a scrub rubs the skin's surface, a peel relies on acids that dissolve the bonds between dead cells. The difference is not just a matter of vocabulary: it changes the gentleness of the action, the possible regularity, and the visible result on the skin texture.

Peeling, scrub, exfoliation: the words and what they cover

These three terms are often used interchangeably. They are not quite synonymous.

• A scrub works by friction, using particles. It is effective on the surface but difficult to control: the pressure applied varies from person to person.
• A peel works chemically, without rubbing. The acids used in cosmetics work on the cohesion of superficial cells.
• Exfoliation is the generic term that encompasses both.

We detail these mechanisms in our guide to exfoliation with AHAs, BHAs, and enzymes.

The three families of active ingredients used

AHAs — glycolic acid, lactic acid — are water-soluble and work on the surface. They are suitable for dry, dull skin or skin marked by texture irregularities. Glycolic acid has the smallest molecule in the group, thus the fastest penetration; lactic acid is considered gentler and also provides a hydrating effect.

BHAs, including salicylic acid, are oil-soluble. They penetrate into the pore, which explains their use on combination to oily skin.

Enzymes, derived from papaya or pineapple, act more slowly and superficially. This is the most gradual approach, often chosen for reactive skin.

What frequency to adopt

This question comes up more often than the choice of acid, and it's the right question. Too frequent a peel weakens the skin barrier: the skin becomes uncomfortable, reacts to products it used to tolerate, and the complexion becomes dull instead of brightening. This is the opposite of the desired effect.

A rhythm of one to two times per week is a reasonable starting point for most skin types. It's better to start less frequently and increase than the other way around. Clear signs of overuse include persistent tightness, redness after application, and a tingling sensation from a product that is usually neutral.

The precautions that really matter

Sun protection. Freshly exfoliated skin is more exposed to UV rays. This is the least negotiable precaution of all, and it determines whether the result is maintained or negated.

Combination with other active ingredients. Combining a peel and a retinoid on the same night is rarely a good idea. Alternating nights allows you to benefit from both without compounding the constraints. Our article on retinol and bakuchiol details these trade-offs.

The skin's initial condition. On damaged, irritated, or actively reacting skin, wait. Exfoliation requires a skin barrier that is in working order.

In-office peels: depths and indications

In aesthetic medicine, the word refers to procedures very different from cosmetic care, and the confusion fosters many disappointed expectations.

Superficial peels act on the epidermis with high concentrations of fruit acids. They aim to improve radiance, skin texture, and minor imperfections. Side effects are minimal: some redness, fine peeling for two to three days. A series of four to six sessions spaced two to three weeks apart is typical.

Medium peels, using trichloroacetic acid, reach the superficial dermis. They are for established spots, fine lines, and shallow acne scars. The after-effects are significant: pronounced peeling for a week, often requiring social downtime.

Deep peels are a heavy medical procedure, reserved for specific indications and specialized practitioners.

In all cases, the initial consultation determines the phototype, skin condition, and contraindications. On darker skin, a poorly chosen peel can cause lasting spots. Skin preparation for several weeks and strict photoprotection after the session are as crucial to the outcome as the procedure itself.

Laser and pulsed light address other indications — vessels, deep spots, sagging — and do not replace a peel. These are complementary techniques, decided upon during consultation.

Three depths are distinguished. Superficial peels use fruit acids at moderate concentrations. Medium peels use trichloroacetic acid, or TCA. Deep peels are regulated medical procedures.

Only the first has a cosmetic equivalent. A gentle at-home peel works on cell renewal and texture appearance; a chemical TCA peel belongs in a clinic, with supervision and strict sun avoidance. Confusing the two is the source of the most common accidents.

Results: what's realistic, and when

What a cosmetic peel does not do: erase established wrinkles, remove deep acne scars, make old spots disappear. For these three indications, it improves the general appearance without treating the cause.

A point rarely mentioned: the radiance achieved primarily comes from the removal of dead cells, not a transformation of the skin. It is a real, immediate result that requires maintenance.

For skin texture, two to three weeks. For hyperpigmentation, at least three months, and never without daily sun protection. For depressed scars, no gentle peel will do anything.

Cell renewal follows its own rhythm, which can be supported but not forced. Applying a soothing cream after each session contributes as much to skin regeneration as the choice of acid itself.

Peeling according to skin type

The same acid is not suitable for all skin types, and incorrect matching explains most bad experiences.

Oily and blemish-prone skin. Salicylic acid is the reference indication: it works inside the pore, where other acids remain on the surface. Once or twice a week on the T-zone, never daily, as this risks reactive overproduction of sebum.

Dry skin. Lactic acid, which hydrates while exfoliating. Always followed by a rich cream, and spaced out — once every ten days is sufficient for skin that renews slowly.

Sensitive and reactive skin. Fruit enzymes first and foremost, or mandelic acid at a low dose. A patch test on the crook of the elbow before the first application to the face avoids many disappointments. See our sensitive skin routine.

Dark skin. Caution takes precedence over potency. Any irritation risks leaving post-inflammatory hyperpigmentation that lasts for months. Mandelic acid, low concentration, wide spacing.

Mature skin. Glycolic acid at a moderate dose improves radiance and texture, but the skin is thinner and repairs more slowly. Once a week, never on the same night as a retinoid.

For oily skin, salicylic acid works better: being oil-soluble, it penetrates into the pore. For dry skin, lactic acid is more suitable, as its larger molecule remains on the surface.

For hyperpigmentation, regularity matters more than strength. A gentle peel every ten days for three months yields more than a strong session every quarter, and without the risk of worsening pigmentation due to irritation.

The application protocol, step by step

The application method influences the result as much as the chosen product.

• Evening only. An exfoliating acid increases sensitivity to ultraviolet light for several days. Applied in the morning, it exposes new skin to radiation.
• On clean and perfectly dry skin. Residual moisture alters the pH and thus the acid's activity.
• Avoid the eye contour, sides of the nose, and lips. These areas are thinner and react more quickly.
• Respect the indicated waiting time, without prolonging it. An acid left on longer does not exfoliate better; it irritates more.
• Rinse thoroughly with lukewarm water if the product instructions recommend it, then apply a soothing and hydrating treatment without delay.
• Sun protection the next morning, without exception, and for the following days.

Increase gradually by frequency before concentration: start once every ten days for a month, then once a week if the skin tolerates it.

What should never be combined

Most domestic accidents come from layering, not from a single product.

Acid and retinoid on the same night. Both accelerate renewal through different pathways. Combined, they strip the skin barrier and cause redness, peeling, and burning sensations. Alternate nights; do not layer.

Two different acids. A glycolic acid toner followed by a salicylic acid serum is equivalent to unknowingly doubling the dose.

Acid and mechanical exfoliation. Chemical exfoliation replaces mechanical exfoliation; it does not add to it.

Acid and planned sun exposure. Before a weekend in the sun or a vacation, suspend use one week prior.

A simple signal should prompt you to stop: if the skin feels tight, red, or tingles for more than an hour after application, the frequency or concentration is too high. A successful exfoliation should not be felt the next day.

The acids used in peels, one by one

Behind the word "peel" are molecules with very different properties. Choosing the right one matters more than the stated concentration.

Glycolic acid is the smallest alpha-hydroxy acid, allowing it to penetrate the deepest. It is the most effective for radiance, skin texture, and spots — and the most irritating. Derived from sugarcane, it is suitable for normal to thick skin, less so for reactive skin.

Lactic acid, being larger, acts less deeply and hydrates while it exfoliates. It is the initial choice for sensitive or dry skin.

Mandelic acid, extracted from bitter almonds, has the largest molecule: slow penetration, excellent tolerance. It is particularly indicated for darker skin, where fast-acting acids risk causing spots.

Salicylic acid is oil-soluble, unique in its category. It penetrates into the pore and dissolves its contents, making it the acid for oily and blemish-prone skin. See our page on salicylic acid.

Fruit enzymes — papain, bromelain — digest the proteins of dead cells without altering pH. Gentle action, no tingling, suitable for very reactive skin and first-timers.

Azelaic acid holds an intermediate position: it exfoliates little but acts on redness and uneven skin tone.

Concentration and pH: the two numbers that matter

A high concentration on a label says almost nothing on its own, which makes comparing products difficult.

An acid's activity depends on its pH. At a high pH, a significant portion of the molecules are neutralized and do not exfoliate. At too low a pH, irritation becomes certain. Serious formulations are between 3.5 and 4: a 10% glycolic acid that is well-buffered is more effective than a poorly formulated 20% product.

The guidelines for home use are simple. Up to 5%, it's for daily or bi-weekly maintenance. Between 5 and 10%, it's for weekly peeling. Above 15%, it enters the realm of use that requires experience and strict progression. Professional concentrations, from 20 to 70%, belong in a clinical setting.

A product that indicates neither concentration nor pH cannot be evaluated. This is not a deal-breaker for a gentle enzyme treatment; it is for an acid advertised as powerful.

A high concentration at neutral pH acts less than a moderate concentration at acidic pH. It is the pH that makes the acid available, and it rarely appears on the packaging—information that serious brands provide upon request.

For home use, five to ten percent at pH 3.5 covers the essentials. Beyond that, you enter the realm of supervised chemical peels, where applying a repair cream afterwards is no longer enough to compensate for the risks.

Peeling according to need

The same action does not serve the same objectives, and the acid is chosen primarily based on the indication.

For radiance and dull complexion, lactic or glycolic acid at a low dose, once a week. This is where the result is fastest: the skin appears brighter from the first application, because the surface is cleared of dead cells that diffuse light.

For imperfections and enlarged pores, salicylic acid, applied locally to the T-zone. See our article on acne and imperfections.

For dark spots, glycolic or mandelic acid, always combined with daily sun protection. Without it, exfoliation exposes new skin to ultraviolet rays and worsens pigmentation. See our guide to dark spots.

For fine lines and wrinkles, the effect of peeling is indirect: it refines the texture and improves the penetration of active ingredients applied afterwards. Retinoids and hyaluronic acid are what work on skin relief, not the exfoliating acid.

In-salon peeling vs. cosmetic peeling

The two terms refer to very different realities. Peels performed by a healthcare professional use concentrations and acids that are not cosmetic. The treatments you apply at home work on the skin's appearance — clarity of texture, luminosity, suppleness — and not on the deeper layers.

For any approach beyond this scope, a dermatologist is the right contact person.

Where to start

If your skin is rather dry or dull, lactic acid offers the gentlest introduction. If it is combination to oily with visible pores, salicylic acid is a better fit. If it is reactive, enzymes allow for progress without being too aggressive.

In all cases, introduce only one new active ingredient at a time, on clean and dry skin, observing the reaction for two to three weeks before adjusting. Our comparison between masks and exfoliants helps situate peeling within an existing routine.

To delve deeper into this specific point, see our guide Home Facial Peel.

Which acid to start with

Of the three families, lactic acid offers the most leeway: its larger molecule penetrates more slowly, so at the same concentration, the risk of discomfort is lower. This makes it a reasonable first peel — a lactic acid peel in the evening, once a week, before considering something stronger.