The Science of Exfoliants: Physical vs Chemical

Exfoliants on the market today currently come in two forms: physical and chemical. They both accomplish the same goal of sloughing off dead skin cells, but they do so in very different ways. It is important to understand the functions of the two exfoliation methods before deciding which one is best for your skin type and needs.

Benefits of Exfoliation

Remove dead skin cells

Exfoliation is an essential step for healthier and younger-looking skin. Throughout the day, dead skin cells build up on the surface of our skin. When these old skin cells start to pile up, it can leave skin looking dull, rough, and uneven. If we neglect to clean our skin well, old makeup, dirt, and oil can also accumulate. The buildup of dead cells results in clogged pores which can lead to blemishes and acne.^[1] The best way to get rid of this build-up of dead skin cells and obtain smooth skin instead is to exfoliate.

Product absorption

One of the most important parts of skincare is product absorption. Product ingredients are more beneficial if the skin is actually absorbing them. Exfoliation of the outermost layers of the skin helps prepare the skin for absorbing products better and is often an added technique during treatment to improve skin appearance and texture.^[2]

Table 1 – Physical vs Chemical Exfoliants

Physical Exfoliation

Commonly labeled as face scrubs, physical exfoliants contain tiny particles that slough off dead skin cells by abrasion. These granule-filled formulas can range from gentle to rough depending on the particles used. The particles used in physical exfoliators are made of a variety of ingredients including salt grains, sugar, jojoba beads, and nutshell granules.

Loofah sponges, bristled shower brushes, and other motorized facial brushes are also considered physical exfoliators. They use force to physically remove the dead skin by sloughing it off the surface.^[3]

Instant results

One benefit of physical exfoliators is that after application, you get an instant gratification of a freshly-scrubbed face that is supple and smooth. Because the particles within the scrub are physically removing dead skin cells right away, the skin is left looking healthy with a naturally glowing complexion.^[4]

Effects on skin barrier

Physical exfoliants need to be handled with care. Many scrubs contain particles such as fruit pits and nutshells that are too large and sharp for delicate facial skin. When they rub against the skin, they can damage the skin barrier.^[5] This can cause the skin to be sensitive and inflamed for several days after application, especially if you have skin that can be reactive.  

Effects on acne-prone or sensitive skin

Physical exfoliants are often too harsh for those with acne or sensitive skin. Irritated skin can lead to further breakouts. It is important not to apply too much pressure when rubbing a scrub into the skin. If you are too rough, it can backfire by making your skin even redder and irritated. A good scrub should easily glide over the skin as you massage it around, and not feel as rough as sandpaper.

Environmental effects of plastic microbeads

A series of studies found that the plastic microbeads in physical exfoliators were not breaking down, but were instead being ingested by marine life and impacting the ocean ecosystem. Fortunately, as of January 2018, the United States, United Kingdom, and the European Union are banning cosmetic products containing non-biodegradable plastic microbeads. Biodegradable beads are currently being researched as an environmentally friendly substitute.^[6]

Chemical Exfoliation

While the word “chemical” may sound intimidating, chemical exfoliants use ingredients such as fruit enzymes and gentle acids to exfoliate your skin. These chemicals are usually used in low doses or buffered with soothing ingredients to minimize any irritation. Often called chemical peels, these products increase cell turnover, and can smoothen and brighten the skin.^[2]

Gentle enough for acne or sensitive skin

Contrary to popular belief, chemical exfoliants can be milder and more gentle than physical scrubs. This is because chemical scrubs do not require scrubbing and work into the skin gradually, which may be more favorable for skin prone to acne, dryness, or sensitivity.^[7]

Alpha hydroxy acids

Alpha hydroxy acids (AHAs) work by dissolving the bonds between skin cells to dislodge dead surface cells from the skin.^[8]  New cells can emerge to the surface once AHAs help to remove the pore-clogging debris from the uppermost skin layer.

AHAs have a small molecular structure and are water-soluble, which can help hydrate and enhance our skin’s natural moisture levels. This can help those with sun damaged and dry skin by diminishing the look of wrinkles and fine lines, smoothening rough skin texture, and improving dull uneven skin tone.^[9]

The two most well-known AHAs are lactic acid and glycolic acid, which are often used in cleansers and serums in varying percentages. Some less commonly used AHAs include mandelic acid, tartaric acid, malic acid, and citric acid.

Beta hydroxy acids

Beta hydroxy acids (BHAs) are best for oily, acne-prone skin. Unlike water-soluble AHAs, whose effects are most noticed on the surface of the skin, BHAs are oil-soluble and can penetrate deeper.^[10] They can break through oil and go deeper into the pores, helping treat blackheads and whiteheads.

They also have anti-inflammatory and antibacterial properties, which is key in preventing newer breakouts from occurring.^[11]

The most popular BHA is salicylic acid, which is commonly used as an active ingredient for treating acne. Less common BHAs include beta-hydroxybutanoic acid, tropic acid or trethocanic acid.

Choosing Between Chemical and Physical Exfoliants

Choosing between the two exfoliation methods is a personal preference and depends on your own skin type and needs.  No matter what you pick, it is important that you follow the packaging instructions which typically recommend using the exfoliator only once or twice a week.

Over-exfoliation can dry out the skin and lead to the overproduction of oil, therefore contributing to more acne. Exfoliating too often in combination with other topical products such as retinoids can also increase the risk of irritation.^[12]

Make your choice based on your needs. If you have no major skin concerns and just want to leave your skin feeling clean and clear, then a physical exfoliant might be best for you. However, if you have acne or sensitive skin, a chemical exfoliant might give you the best results.

To learn more about exfoliants and skin care, click on the articles below:

Plant Exfoliators

Should I Exfoliate to Help Acne? 

1. Zouboulis CC. Acne and sebaceous gland function. Clin Dermatol.2004;22(5):360-366; PMID: 15556719 Link to research.
2. Rendon MI, Berson DS, Cohen JL, et al. Evidence and considerations in the application of chemical peels in skin disorders and aesthetic resurfacing. J Clin Aesthet Dermatol.2010;3(7):32-43; PMID: 20725555 Link to research.
3. Draelos ZD. Concepts in skin care maintenance. Cutis.2005;76(6 Suppl):19-25; PMID: 16869178 Link to research.
4. Holck DE, Ng JD. Facial skin rejuvenation. Curr Opin Ophthalmol.2003;14(5):246-252; PMID: 14502051 Link to research.
5. Collier M, Simon D. Protecting vulnerable skin from moisture-associated skin damage. Br J Nurs.2016;25(20 Suppl):S26-S32; PMID: 27834525 Link to research.
6. Kitsongsermthon J, Kreepoke J, Duangweang K, et al. In vivo exfoliating efficacy of biodegradable beads and the correlation with user's satisfaction. Skin Res Technol.2018;24(1):26-30; PMID: 28543622 Link to research.
7. Al-Talib H, Al-Khateeb A, Hameed A, et al. Efficacy and safety of superficial chemical peeling in treatment of active acne vulgaris. An Bras Dermatol.2017;92(2):212-216; PMID: 28538881 Link to research.
8. Clark E, Scerri L. Superficial and medium-depth chemical peels. Clin Dermatol.2008;26(2):209-218; PMID: 18472062 Link to research.
9. Fischer TC, Perosino E, Poli F, et al. Chemical peels in aesthetic dermatology: an update 2009. J Eur Acad Dermatol Venereol.2010;24(3):281-292; PMID: 19744174 Link to research.
10. Wiest L. [Chemical peels in aesthetic dermatology]. Hautarzt.2004;55(7):611-620; PMID: 15179505 Link to research.
11. Saviuc C, Ciubuca B, Dinca G, et al. Development and Sequential Analysis of a New Multi-Agent, Anti-Acne Formulation Based on Plant-Derived Antimicrobial and Anti-Inflammatory Compounds. Int J Mol Sci.2017;18(1)PMID: 28106736 Link to research.
12. Draelos Z, Lewis J, McHugh L, et al. Novel retinoid ester in combination with salicylic acid for the treatment of acne. J Cosmet Dermatol.2016;15(1):36-42; PMID: 26516077 Link to research.