Exfoliation: What It Is, Types and Complete Guide

Exfoliation: What It Is, Types and Complete Guide

Exfoliation is the controlled elimination of dead cells that accumulate in the stratum corneum, the outermost layer of the skin. Under ideal conditions, the skin renews its cells naturally —a process known as desquamation—, but factors such as age, sun exposure and hormonal changes slow it down. When dead cells accumulate, the skin appears dull, the texture becomes irregular and pores become clogged more easily.

Exfoliating properly accelerates cell renewal, improves the absorption of active ingredients and contributes to a more uniform tone. But not all exfoliation methods work the same way or suit the same skin type. In this guide we explain the four types of exfoliation, how the most commonly used acids compare and when it is advisable to resort to a professional treatment.

In summary

• Exfoliation removes dead cells from the stratum corneum to improve texture, luminosity and absorption of active ingredients.
• There are four categories: physical (mechanical), chemical (AHA, BHA, PHA), enzymatic and professional/clinical.
• AHAs are water-soluble and ideal for dry or photo-aged skin; BHAs are oil-soluble and penetrate the pore, making them preferable on oily or acne-prone skin; PHAs have larger molecules and are the gentlest option for sensitive skin.
• Professional exfoliation —chemical peelings and Hydrafacial— reaches deeper layers than any home-use product.
• Sunscreen is mandatory after exfoliating: the skin becomes more vulnerable to ultraviolet radiation.

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What is exfoliation and why does your skin need it?

Exfoliation is the process of removing dead cells (corneocytes) from the skin surface to promote cell renewal. The skin renews itself from bottom to top: keratinocytes are born in the basal layer of the epidermis, migrate to the surface and, upon reaching the stratum corneum, are no longer living cells but flat "scales" filled with keratin that eventually shed.

In young and healthy skin, this complete cycle takes approximately 28 days, although more recent studies suggest that the actual average may be 40 to 56 days and extends even longer with age. From age 30-35 onwards, cumulative sun exposure, hormonal changes and slowed metabolism cause natural desquamation to lose efficiency. The result: a thicker layer of dead cells that dulls luminosity, accentuates fine lines and prevents active ingredients from penetrating.

Exfoliation —whether with a home product or a clinical procedure— helps to compensate for this deficit. By removing excess corneocytes you achieve:

• Smoother texture and visually reduced pores.
• Greater luminosity: without the dull layer of dead cells, light reflects more uniformly.
• Better absorption of active ingredients: serum, moisturizer and sunscreen penetrate more effectively.
• Prevention of comedones: by preventing dead cells from clogging the follicle, the formation of blackheads and acne breakouts is reduced.

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Types of exfoliation: the four categories

There are four major methods for exfoliating the skin. Each acts through a different mechanism and has a different profile of intensity, indications and risks.

Physical exfoliation (mechanical)

Physical exfoliation removes dead cells through direct friction. It is the oldest and most intuitive method: any material with a granular texture or an abrasive surface that is rubbed against the skin falls into this category.

Common examples:

• Scrubs or granular exfoliants (with sugar particles, salt, silica microspheres, rice powder).
• Konjac sponges, facial brushes, exfoliating gloves.
• Microdermabrasion (professional version that projects microcrystals or uses a diamond-tip).

Advantages: immediate effect, easy to use, does not require prior knowledge of chemical actives.

Limitations: if the particles are irregular or too aggressive (for example, crushed nut shells), they can generate microfissures in the epidermis. Pressure is difficult to standardize, which increases the risk of irritation. In skin with active acne or rosacea, friction can worsen inflammation.

General recommendation: if you opt for a physical exfoliant, choose formulas with spherical particles of uniform size, and apply with gentle pressure and short circular motions. Limit its use to once or twice a week.

Chemical exfoliation (AHA, BHA, PHA)

Chemical exfoliation uses acids or keratolytic compounds that dissolve the bonds (desmosomes) between corneocytes, allowing them to shed without mechanical friction. It is the type of exfoliation with the most scientific backing and the basis of most professional resurfacing treatments.

Exfoliating acids are grouped into three families:

• AHA (alpha-hydroxy acids): water-soluble, they act on the surface of the epidermis. They are ideal for dry, photo-aged or hyperpigmented skin. Examples: glycolic acid, lactic acid, mandelic acid, tartaric acid, citric acid.
• BHA (beta-hydroxy acids): oil-soluble, which allows them to penetrate inside the pore and dissolve excess sebum. The BHA most used in cosmetics is salicylic acid. They are the first choice in oily and acne-prone skin, thanks to their keratolytic, antiseptic and anti-inflammatory action.
• PHA (polyhydroxy acids): they have a significantly higher molecular weight than AHAs and BHAs, so they penetrate more slowly and cause less irritation. Additionally, they have humectant and antioxidant properties. Examples: gluconolactone, lactobionic acid, galactose. They are the reference option for sensitive skin, rosacea or after procedures.

The following section presents a detailed comparative table of the most relevant acids.

Enzymatic exfoliation

Enzymatic exfoliation uses proteolytic enzymes —mainly of plant origin— that digest the keratin of dead cells without altering the skin's pH or requiring friction. It is the gentlest exfoliation method and the one with the lowest risk of irritation.

The most commonly used enzymes are:

• Papain (from papaya): breaks down keratin bonds on the skin surface. Effective for unclogging pores and softening texture.
• Bromelain (from pineapple): in addition to its proteolytic action, it has documented anti-inflammatory properties, making it useful in reactive skin or with redness.
• Fungal enzymes (keratinases, subtilisin): of microbiological origin, they offer a broader enzymatic profile and gentle but effective exfoliation.

Enzymatic exfoliation is especially recommended for sensitive skin that does not tolerate acids, and as a preparatory step before a professional treatment. Its main limitation is that its action is more superficial than that of an AHA or BHA at relevant concentrations.

Note: people with allergies to pineapple or papaya should avoid formulations with bromelain or papain, respectively.

Professional / clinical exfoliation

Professional exfoliation is performed in a clinical or medical setting and uses concentrations of acids, technologies or combinations that are not available in home-use products. It allows reaching deeper layers of the skin and obtaining more pronounced results in fewer sessions.

The two major pillars are chemical peelings (with acids at controlled concentrations) and technology-assisted exfoliation treatments such as Hydrafacial. The section dedicated to professional exfoliation further down explores both.

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AHA vs. BHA vs. PHA: comparative table

The following table summarizes the key differences between the exfoliating acids most used in dermocosmetics.

Reading keys:

• The lower the molecular weight, the greater the penetration and the greater the potential for both efficacy and irritation. Glycolic acid (76 Da) penetrates faster than mandelic acid (152 Da) or gluconolactone (178 Da).
• Solubility determines where the acid acts. Water-soluble acids (AHA, PHA) work on the surface of the epidermis. Oil-soluble ones (BHA) dissolve in sebum and access the interior of the follicle, making them superior for treating comedones and acne.
• PHAs combine exfoliation with humectation, as they attract water molecules to the skin. This is why they are the first choice for skin with a compromised barrier.

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What type of exfoliation to choose according to your skin

The choice of exfoliant should not be made by fashion or generic recommendation. The most useful criterion is skin type and the main concern you want to address.

Oily or acne-prone skin

BHA (salicylic acid) is the first choice. Being lipophilic, it penetrates the grease that clogs the pore and acts from within. Its anti-inflammatory effect helps reduce active breakouts. Usual concentrations in cosmetics: 0.5%–2%. In case of moderate to severe acne, a dermatologist can prescribe salicylic acid peelings at 20–30% in consultation.

Dry or dehydrated skin

Medium molecular weight AHAs, such as lactic acid, exfoliate the surface without compromising hydration. In fact, lactic acid is part of the skin's natural moisturizing factor (NMF), so it strengthens the skin barrier while eliminating dead cells. Usual concentrations: 5%–10%.

Mature or photo-aged skin

Glycolic acid, having the lowest molecular weight of the AHAs (76 Da), penetrates more effectively and stimulates the synthesis of collagen and dermal hyaluronic acid. It is the reference active ingredient for irregular texture, fine lines and mild sun spots. Usual concentrations: 5%–10% in daily cosmetics, up to 70% in professional peelings.

Sensitive skin or with rosacea

PHAs (gluconolactone, lactobionic acid) offer exfoliation with minimal risk of irritation, thanks to their high molecular weight. Another alternative is enzymatic exfoliation with papain or bromelain, which does not modify skin pH. It is important to avoid physical exfoliation and low molecular weight AHAs, as they can trigger redness and rosacea breakouts.

Mixed or normal skin

Glycolic acid at low-medium concentrations (5%–8%) is usually well tolerated and offers a good balance between efficacy and tolerability. You can also alternate with salicylic acid in the T-zone if there is a tendency to dilated pores or blackheads.

Hyperpigmentation or melasma

Mandelic acid is particularly useful: its partially lipophilic structure and slower penetration reduce the risk of post-inflammatory hyperpigmentation, an adverse effect especially relevant in higher phototypes (Fitzpatrick IV-VI). In active melasma, the approach should be cautious; PHAs or mandelic acid at low concentration are preferred, always under professional supervision and with strict sun protection.

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Professional exfoliation: chemical peelings and Hydrafacial

Professional exfoliation uses concentrations of actives and technologies that exceed what any over-the-counter product can offer. It is performed in a controlled clinical setting by trained professionals, which allows adjusting the depth of exfoliation to the therapeutic goal.

Chemical peelings: the depth spectrum

A chemical peeling consists of the controlled application of an acidic solution to the skin to produce uniform and predictable exfoliation. The depth of the peeling —and therefore its results and recovery— depends on the type of acid, its concentration, the exposure time and the number of layers applied.

Superficial peeling (epidermis)

• Acids: glycolic 20–30%, salicylic 20–30%, Jessner's solution, TCA 10–15%.
• Depth: acts within the epidermis, without reaching the dermis.
• Indications: irregular texture, dilated pores, mild spots, general maintenance.
• Recovery: minimal or none. There may be slight redness and fine desquamation for 1–3 days.
• Usually requires several sessions for optimal results.

Medium peeling (papillary dermis)

• Acids: TCA 35% combined with Jessner's solution, glycolic acid 70% + TCA 35%, or solid CO₂ + TCA 35%.
• Depth: penetrates to the papillary dermis (superficial dermis).
• Indications: moderate wrinkles, superficial acne scars, resistant hyperpigmentation, moderate sun damage.
• Recovery: 5–7 days of visible desquamation, redness that may persist for weeks. Strict post-procedure care is required.
• Generally, a single session produces significant results.

Deep peeling (reticular dermis)

• Acids: phenol-croton oil or TCA at high concentrations (≥50%).
• Depth: reaches mid-reticular dermis.
• Indications: deep wrinkles, severe scars, advanced sun damage.
• Recovery: significant; 2–3 weeks of social inactivity, risk of permanent pigmentary changes.
• Requires medical monitoring and, in some cases, sedation. Not suitable for higher phototypes due to risk of hypopigmentation.

Regulatory context: peelings at medium and deep concentrations are medical acts that, according to the legislation of each country, must be performed by physicians or under their direct supervision. Agencies such as the FDA (USA), EMA/AEMPS (Europe), COFEPRIS (Mexico), ANVISA (Brazil) and INVIMA (Colombia) regulate the chemicals used and, in some cases, the authorized establishments.

Hydrafacial: exfoliation + hydration in one step

Hydrafacial is a professional facial treatment based on Vortex-Fusion® technology that combines cleansing, exfoliation, extraction and hydration in a single session, without acids at high concentrations or recovery time.

The device uses spiral-shaped tips that generate a vortex effect through vacuum suction. This mechanism performs a dual simultaneous function: it removes dead cells, sebum and debris from inside the pore while simultaneously infusing serums with hyaluronic acid, peptides and antioxidants into the cleansed skin.

Key differences from a chemical peeling:

Hydrafacial is especially useful as a maintenance treatment between peeling sessions, or as an option for patients seeking luminosity and hydration without downtime.

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Common mistakes and precautions

Over-exfoliation

Over-exfoliation occurs when cells are removed faster than the skin can regenerate them. Signs include persistent redness, feeling of tightness or burning, excessive desquamation and increased sensitivity to products that were previously well tolerated. If these symptoms appear, the recommendation is to pause all exfoliation for at least two weeks and focus on repairing the skin barrier with ingredients such as ceramides, hyaluronic acid and niacinamide.

Mixing acids without criteria

Combining an AHA with a BHA in the same routine can be effective in formulas designed for it, but applying products from different brands or concentrations without professional guidance multiplies the risk of irritation. Exfoliating acids should never be combined with retinoids in the same application except on express indication from a dermatologist.

Exfoliating skin with active inflammatory acne

Physical exfoliation on pustules or inflamed nodules can break the skin, spread bacteria and worsen the breakout. In active inflammatory acne, the only recommended exfoliation is chemical (BHA at low concentration) and always under professional supervision if the acne is moderate or severe.

Forgetting sunscreen

Any form of exfoliation —even enzymatic— leaves the skin temporarily more vulnerable to ultraviolet radiation. Using broad-spectrum sunscreen (SPF 30 minimum, ideally SPF 50) is mandatory during the entire period you exfoliate and for at least a week after any professional peeling. Without photoprotection, the risk of post-inflammatory hyperpigmentation cancels out the benefits of exfoliation.

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Frequently asked questions

What is exfoliation?

Exfoliation is the process of removing dead cells accumulated in the most superficial layer of the skin (stratum corneum). The skin constantly renews itself: keratinocytes are born in the deep layers of the epidermis, migrate to the surface and, when they reach the top, are dead cells rich in keratin that eventually shed naturally. Exfoliating helps to accelerate that process when natural desquamation becomes insufficient —something that occurs with age, sun exposure and certain hormonal imbalances—, improving texture, luminosity and absorption of other care products.

What are the types of exfoliation?

The four main types are: physical (mechanical), chemical (AHA, BHA, PHA), enzymatic and professional/clinical. Physical exfoliation removes dead cells through friction; chemical exfoliation uses acids that dissolve bonds between corneocytes; enzymatic exfoliation uses proteolytic enzymes that digest keratin; and professional exfoliation uses concentrations or technologies for exclusive use in medical consultation, such as controlled chemical peelings and Hydrafacial. The choice depends on skin type, individual sensitivity and the desired goal.

What is an exfoliant?

An exfoliant is any product or instrument designed to facilitate the removal of dead cells from the skin surface. It can be a scrub with granular particles (physical exfoliant), a serum or tonic with acids such as glycolic or salicylic (chemical exfoliant), or a mask with papaya or pineapple enzymes (enzymatic exfoliant). The term also applies to devices such as facial brushes or microdermabrasion tips. Most importantly is not the category, but choosing the right exfoliant for your skin type and respecting the recommended frequency.

What does it mean to exfoliate?

Exfoliating means removing in a controlled manner the dead cells from the outer layer of the skin to stimulate cell renewal. It is a verb that describes the action, regardless of the method used: you can exfoliate with a scrub, with an acid, with an enzyme or with a professional treatment. The goal is always the same: to expose a layer of newer, smoother skin that is more receptive to the actives in your care routine.

What is the difference between physical and chemical exfoliation?

Physical exfoliation removes dead cells through mechanical friction (particles, brushes, sponges), while chemical exfoliation does so through acids that dissolve intercellular bonds without the need to rub. Chemical exfoliation allows more precise control of the depth and uniformity of exfoliation, and is usually better tolerated by sensitive or acne-prone skin. Physical exfoliation offers immediate results and does not require knowledge of actives, but its intensity is harder to dose and is not recommended on inflamed skin.

What is an AHA and a BHA?

AHA (alpha-hydroxy acid) and BHA (beta-hydroxy acid) are two families of exfoliating acids. AHAs —such as glycolic and lactic— are water-soluble and work on the surface of the epidermis, ideal for dry skin or with signs of photo-aging. BHAs —fundamentally salicylic acid— are lipophilic: they penetrate inside the pore, dissolve sebum and have an anti-inflammatory effect, making them the preferred option for oily and acne-prone skin. Both families are keratolytic (they break the bonds between dead cells), but their solubility determines where they concentrate their action.

How often should I exfoliate my skin?

It depends on the type of exfoliation and individual tolerance. As a general guide: gentle physical exfoliants can be used once or twice a week; serums with AHA or BHA at low concentrations (5%–10%) can be applied daily or on alternate days if the skin tolerates it; and PHAs or enzymatic exfoliants are gentle enough for frequent use. Superficial professional peelings are usually spaced every 2–4 weeks; medium depth ones, every 3–6 months. The most important rule is to listen to your skin: if redness, tightness or excessive desquamation appears, reduce the frequency.

What is a chemical peeling?

A chemical peeling is a medical-aesthetic procedure in which a controlled acidic solution is applied to the skin to produce uniform exfoliation at a predetermined depth. Depending on the acid and concentration, the peeling can be superficial (epidermis only), medium (to the papillary dermis) or deep (reticular dermis). Superficial ones treat irregular texture, pores and mild spots with minimal recovery. Medium ones address moderate wrinkles and scars, with 5–7 days of desquamation. Deep ones, indicated for severe sun damage, require weeks of recovery and medical monitoring.

Is exfoliation good for acne?

Yes, when the correct method is chosen. Salicylic acid (BHA) is the reference exfoliant for acne because it is lipophilic —it penetrates inside the pore to dissolve the plug of sebum and dead cells— and has anti-inflammatory and antiseptic properties that help reduce bacteria involved in breakouts. AHAs such as glycolic acid can complement treatment by improving texture and preventing post-inflammatory hyperpigmentation. However, physical exfoliation is contraindicated on active inflammatory lesions: friction can break pustules, spread bacteria and worsen the condition.

Can you exfoliate sensitive skin?

Yes, as long as you choose a low-aggressiveness method. PHAs (gluconolactone, lactobionic acid) are the safest acids for sensitive skin: their high molecular weight limits penetration and minimizes irritation, and they also provide hydration. Enzymatic exfoliation (papain, bromelain) is also a suitable option, as it works without modifying skin pH. What should be avoided on sensitive skin is aggressive physical exfoliation and low molecular weight AHAs (such as glycolic) at high concentrations. It is always advisable to start with the lowest possible concentration and increase gradually.

What is Hydrafacial?

Hydrafacial is a professional facial treatment that uses Vortex-Fusion® technology to cleanse, exfoliate, extract impurities and hydrate the skin in a single session. The device generates a vortex effect through vacuum suction and spiral-shaped tips: it removes dead cells and pore debris while simultaneously infusing serums with hyaluronic acid, peptides and antioxidants. Unlike a chemical peeling, Hydrafacial does not produce desquamation nor requires recovery time, making it a popular option for maintenance, event preparation or skin that does not tolerate acids at high concentrations.

Why is it important to use sunscreen after exfoliating?

Because exfoliation removes the layer of dead cells that acts as the first barrier against ultraviolet radiation. Without that layer, the skin is more exposed to UVA and UVB rays, which increases the risk of burns, spots and damage to cell DNA. This effect is especially marked after a chemical peeling, but also applies after the use of AHA, BHA or even enzymes. A broad-spectrum sunscreen with SPF 30 minimum (ideally SPF 50) is recommended during the entire period of active exfoliation and for at least a week after any professional procedure. Without photoprotection, the benefits of exfoliation are negated —or worse, they become damage.