Exfoliation – A Guide To AHAs, BHAs, And Enzymes For Youthful, Healthy Skin

Jun 21, 2024
15 min read

Updated: Aug 2

Written by Ida Fanelli, Aesthetician, Reflexologist & IPL & Dolphin MPS Technician

Ida is a certified aesthetician (graduate of Marvel School of Beauty), offering home-based services since 1994. Ida provides various holistic services. She graduated from Zanqara’s Skin Care’s Dermatician course in 1994, which required her to understand homeopathic remedies.

Cell replacement and exfoliation processes slow down as skin ages, partly due to decreased enzymes that break down dead skin cells. This decline can compromise the skin's barrier, leading to dryness and a dull complexion. Regular exfoliation helps counteract these effects by preventing clogged pores, reducing breakouts, and indirectly stimulating collagen production and skin elasticity, this leads to clearer, brighter, and smoother skin, which in turn improves the absorption of skincare products, essential for maintaining a youthful, healthy appearance. I share the strengths and weaknesses of various exfoliators, including alpha-hydroxy acids (AHAs), beta-hydroxy acids (BHAs), polyhydroxy acids (PHAs), and enzyme-based exfoliators, providing insights into their chemical compositions, benefits, and potential contraindications.

AHA's

Alpha-hydroxy acids – AHAs are fruit acids. Skincare manufacturers synthetically produce most of them, which means they do not have the whole fruit source benefits.

Common AHAs include:

Glycolic acid from sugar cane.
Citric acid from citrus fruits.
Malic acid from apples.
Lactic acid from milk.
Tartaric acid from grapes.
Mandelic acid from Almonds

Glycolic acid

Glycolic acid is the smallest molecule in the alpha-hydroxy acid (AHA) family. Its water solubility and tiny size allow it to penetrate the skin more effectively than other AHAs, making it a popular ingredient in cosmetic formulations.

Although often promoted as being derived from sugar cane, the reality is that much of the glycolic acid presently used in skincare goes through industrial chemical synthesis of glucose. This process includes petrochemical derivatives such as mono-chloroacetic acid and formaldehyde. Large-scale facilities in China and India frequently use glucose fermentation followed by formaldehyde-based processing—a compound better known for preserving biological tissues or as an industrial cleaning agent. Petrochemical methods may also leave behind trace amounts of formaldehyde in the final product.

Industrial applications

Beyond beauty, glycolic acid plays a vital role in industrial and medical fields:

They use it to weaken collagen bonds to aid in tanning for textiles & leather. Products contain it to remove rust, scale and mineral deposits. They process it into biodegradable polymers for absorbable sutures, surgical screws, and controlled drug delivery systems. Direct consumption of glycolic acid or products that convert to glycolic acid, like antifreeze, can cause acute renal failure, metabolic acidosis and death.

These applications don't make glycolic acid unsafe in cosmetics as long as manufacturers strictly adhere to regulatory safety limits. According to Health Canada's Cosmetic Ingredient Hotlist, consumer products containing alpha-hydroxy acids (AHAs) must have a concentration of 10% or less, and the formulation must maintain a pH of 3.5 or higher. Products designed for professional use may contain up to 30% AHA with a minimum pH of 3.0, provided they are explicitly labeled for professional application.

However, they do highlight its industrial origins and raise essential questions about sourcing and sustainability.

Sustainable alternatives and consumer guidance

VOC-free fermentation technology exists, which produces glycolic acid from renewable, plant-based sources rather than petrochemicals. This method reduces environmental impact and avoids issues linked to formaldehyde residues.

Look for products labelled bio-based or formaldehyde-free to make more eco-conscious choices.

Seek USDA Certified Bio-Based Product labelling, which verifies renewable sourcing and confirms the absence of petrochemical contaminants.

The Environmental Working Group (EWG) gives glycolic acid a 3-6 fair rating depending on usage. On a scale from one to ten, the higher the rating, the worse the score.

Manufacturers selling in Canada must fully comply with the exact cautionary labelling requirements outlined in Health Canada's Cosmetic Ingredient Hotlist for AHA-containing products. Health Canada cautions untrained consumers against using high-concentration professional peels at home and restricts retail access to safe consumer-level formulations.

How glycolic acid works on your skin

Bio-based glycolic acid comes from natural sources like sugar cane and plants. It is the most exfoliating AHA; it loosens the "glue," aka desmosomes, that hold the dead skin cells together, helping them shed and revealing a smoother, glowing complexion.

Tiny amounts seep into the body, which quickly break down into completely safe substances your body already produces, such as the amino acid glycine. For the most part, glycolic acid stays on the surface, working only where you want it to. When used in professional treatments, it's always neutralized so it doesn't go deeper than intended.

Higher strengths exceeding 10% concentration are restricted by Health Canada and are permitted only for professional use by trained specialists, ensuring they are never sold directly to the general public for unsupervised application.

Risk of permanent skin damage: If the glycolic peel is too strong or left on for too long, it can lead to permanent skin damage, such as hyperpigmentation and scarring. People with darker copper-toned complexions have a higher risk of post-inflammatory hyperpigmentation.
Scarring from using strong peels: There's a low risk of scarring from high concentrations, particularly for those prone to keloids or abnormal skin scarring. Before undergoing the peel, it is essential to inform your dermatologist of any history of such conditions.
Skin thinning: Prolonged use can thin the skin's outer layer, increasing sensitivity and potential damage.
Infection and allergic reactions: Infections are rare if the client doesn't follow the skin's aftercare instructions correctly post-peel.

Sun sensitivity, hyperpigmentation, and other risks

AHAs, including glycolic acid, significantly increase skin sensitivity to UV radiation. To comply with Health Canada mandates, the outer packaging of all retail AHA products must include a dedicated Sunburn Alert warning. The required labeling must explicitly instruct consumers to use a sunscreen, wear protective clothing, and limit sun exposure while using the product and for a week afterward.

To fully comply with Health Canada mandates for any leave-on skin product containing AHAs (or PHAs) at concentrations of 3% or greater, the product packaging must feature explicit directions for safe use. The label must explicitly state: "Use only as directed," "Avoid contact with the eyes," "If irritation persists, discontinue use and consult a physician," and "It is recommended that prior to exposure to the sun, users cover areas where AHAs have been applied with sunscreen

Irritation

Glycolic acid can be exceptionally irritating if used excessively or if the products are too strong. Discontinue use and rinse the skin with clean water when the skin demonstrates irritation, redness, itching, swelling, or burning.

Benefits are short-term

AHA and acids produce a temporary improvement in the condition of the skin. Fine lines and mild puffiness that tighten the skin do not last. The thinning of the outermost layer of skin against the elements increases the possibility of sunburn and sensitivity for up to a week after application. It makes skin appear shiny by removing the protection your skin requires against the elements.

Repetitive sun damage may cause crepey skin. Long-term results cause the skin to lose retraction and elasticity as its elastin fibres break down. The connective tissue protein collagen also weakens. The fat in the lowest layer of the skin becomes uneven and flattens. Surface capillaries become more fragile, causing bruising. This layer also becomes drier and more transparent as skin loses pigment, and the cells in this area begin shrinking. The Sun's UV rays also damage the skin's lymphatic system, affecting the immune system and its ability to clean out impurities.

Precautions for glycolic acid use

Do not use on Infants and Children.
Do not use on pregnant and breastfeeding clients.
Do not use on broken, irritated, sore, or sunburned skin. Avoid use over active skin flares or recently microneedled areas
Individuals with redness, blushing, or sensitive skin should avoid it.
Cancer survivors and people with weak immune systems should avoid topical application of chemical peel treatments and products.
Perform a patch test to determine a client's tolerance
Start with lower concentrations and increase gradually.
Rinse eyes immediately if it gets into the eyes.
Use sun protection daily when using AHAs/BHAs.
The skin typically becomes dry and peels during the healing process. Use moisturizers and gentle skincare during this period to aid recovery.
Avoid AHA peels when using retinol
Avoid altogether when using Accutane or other medications

Lactic acid

Lactic acid is larger than glycolic acid. It is a less irritating AHA that doesn't compromise the lipid barrier with overuse. It's naturally in sour milk. Lactic acid in skincare is typically synthetic or plant-derived.
Plant-derived sources: Lactobacillus bacteria ferment plant-based materials, such as corn starch or beet sugar, to produce lactic acid. It meets ethical and environmental considerations.
Synthetic production: Lactobacillus cultures ferment carbohydrates such as glucose or sucrose to produce lactic acid. Calcium carbonate (chalk) is added to maintain pH levels and is indirectly a part of the fermentation environment.

It offers humectant properties, increases natural ceramides, and provides brightening benefits. It also promotes cell renewal, firmness, hydration, smoothness, and reduced lines and wrinkles, making it a gentler alternative. It may pose risks if used excessively.

Our body requires lactic acid as a fuel source for mitochondria in all cells

It enables glucose production
It signals where you need healing

Side effects of lactic acid

When introducing Lactic Acid into a skincare routine or using it at higher concentrations, some people might experience temporary skin irritation.
Excessive use can cause dryness, weakening the skin's protective layer and making it more sensitive to the sun. Use sun protection.
The topical application of lactic acid in skincare products does not cause specific concerns about entering the bloodstream in significant amounts, so all skin types, including pregnant and breastfeeding women, can accept it.
The EWG rates it 2 to 5, stating that the rating would be worse if it were in inhalable products. They see it as a safer ingredient in solids and liquids.

Citric acid

Citric acid has a larger molecular size. It is naturally found in citrus fruits and is primarily produced through the microbial fermentation of sugars by a specific strain of the fungus Aspergillus Niger. It multitasks as a skincare ingredient. As both an exfoliant and antioxidant, it helps brighten and smooth the skin, even out tone, and reduce hyperpigmentation and fine lines. It gently sheds dead skin cells to support a fresher, more radiant complexion. It is a mild astringent that balances the pH and helps tighten the appearance of pores.

It is a gentler AHA option, though sensitive or recently sun-exposed skin types should use it cautiously.

Mineral interactions

Citric acid is chemically unstable when exposed to light, heat, oxygen, or metal ions such as iron and copper.
It can bind iron and copper, which helps reduce metal-driven oxidative stress that contributes to aging and pigmentation.
Its instability in the presence of metals and UV light can lead to pro-oxidant activity, generating free radicals that may stress skin cells if not properly formulated.
The EWG rates it as a lower risk 1 creams, serums, liquids and as a 2 for inhalable products (sprays, powders) due to respiratory irritation.

Malic acid

Malic acid, a naturally occurring alpha-hydroxy acid (AHA) found in apples, pears, and other fruits, is best known for giving fruit its tart taste. In skincare, it provides gentle exfoliation that helps remove dead skin cells, smooth rough texture, reduce the look of fine lines, and restore a healthy radiance.

Malic acid has a relatively small molecular size, penetrates effectively while also supporting the skin's ability to retain moisture—leaving it softer and more hydrated. It is milder, making it a suitable option for those with sensitive skin (though we recommend a patch test.

From a safety perspective, the EWG rates malic acid between 1 and 4, depending on the product type. The score is higher when used in inhalable products, and lower when included in creams, gels, or serums.

Synthetic DL-Malic acid is a cost-effective method, where it is created chemically by mixing equal parts of D-malic acid and L-malic acid. It is a safe form used in cleaning agents, industrial formulations, skincare blends, and processed foods. It has no nutritional value for humans.

Natural L-Malic Acid is derived naturally from fruits such as apples and bananas or produced through fermentation processes that favour the active L-isomer. It is compatible with the human body and supports natural energy production when consumed. Manufacturers use in foods and beverages, as well as clean-label skin care products, for gentle yet effective exfoliation with added hydration benefits.

Tartaric acid

Tartaric acid, an alpha hydroxy acid (AHA) made from wine and cream of tartar. It provides multiple skin benefits. It's a gentle exfoliant, helping to loosen and shed dead skin cells, revealing fresher, healthier-looking skin. It protects against free radical damage, regulates pH, supports overall skin balance enhances other active ingredients effectiveness in the formulation. Additionally, tartaric acid helps the product stability, making it a valuable ingredient in cosmetic formulations.

With its relatively small molecular size, tartaric acid penetrates the skin effectively. The EWG rates it a safe score of 1, in properly formulated products, though current safety data are somewhat limited.

Pet safety warning

Tartaric acid is toxic to dogs if ingested, even in small amounts. Pet owners should store skincare and cosmetic products containing tartaric acid out of reach of pets to prevent accidental ingestion. Cream of Tartar is also toxic to dogs.

Avoid letting a dog lick your face if you've used any skincare products containing these ingredients.

Mandelic acid is an alpha-hydroxy acid (AHA) derived from bitter almonds and now also synthesized in labs from benzaldehyde reacting with hydrogen cyanide. The EWG rates it as a one, very safe. It's a gentler skin exfoliator that helps control hyperpigmentation, manage breakouts due to its antibacterial properties, and achieve a smoother, brighter skin tone. It has a large molecular size and penetrates the skin slowly. It is a less irritating option, particularly suitable for sensitive skin.

Beta Hydroxy Acids (BHAs)

BHA, like salicylic acid, is oil-soluble and treats oily and acne-prone skin. Salicylic acid, derived from willow bark, effectively unclogs pores and reduces blackheads and whiteheads. Because of its potency and risk of skin irritation, Health Canada restricts the concentration of salicylic acid in topical cosmetic formulations to a maximum of 2%

The EWG rates Salicylic acid 5-8 and states that the rating would be higher (worse) if it is in products that cause respiratory concerns, such as inhalable products. They see it as a safer ingredient in solids and liquids.

Trethocanic acid is another BHA, is derived from pine bark and is more potent, though less common.

Polyhydroxy Acids (PHAs)

PHAs, such as lactobionic acid, are gentle and non-irritating, making them suitable for sensitive skin. The EWG approves lactobionic acid and rates it as a 1. However, from a regulatory standpoint, Health Canada officially groups Polyhydroxy Acids (PHAs) and bionic acids under the Alpha-hydroxy acids (AHAs) Hotlist entry, meaning they must still comply with the broader safety and pH requirements set for traditional AHAs.

The enzyme-based exfoliators

Enzymes are naturally complex proteins that increase the rate of protein-based reactions without undergoing the reactions themselves. They break down skin proteins into peptides and amino acids, which the skin absorbs to generate new cell growth. Enzyme exfoliators, like those derived from papaya, pineapple, pomegranate, cherries, and pumpkin, offer a gentler alternative to chemical exfoliators without the risk of sunburn peeling. Proteolytic enzymes are also used in digestive enzymes to help the body assimilate protein from food.

My experience with enzyme peels

I am a Holistic Aesthetician. I've performed Zanqara's enzyme peel and Zanqara Profile peel since 1994. The enzyme peel breaks up dead skin cells and removes one layer of live skin cells. It deeply exfoliates the skin and refines pores without being overly harsh or stripping. I've used it on sensitive and oily skin types. The Profile Peel is less aggressive but has skin-tightening qualities. I can add various extracts to personalize for all skin types. Both bromelain and papain are proteolytic enzymes which break down proteins into smaller peptides, including collagen peptides. These peptides can act as signal peptides, stimulating skin fibroblasts to increase new collagen and elastin fibres production, which are essential for skin structure and elasticity. This process is a key mechanism for skin renewal, regeneration, and improving firmness and hydration. Both peels have less downtime from sun exposure. Enzymes work optimally at body temperature.

Bromelain

Bromelain is the main reason pineapple is known to have skin-beautifying and brightening properties. It has concentrated bromelain in the pineapple core, stem, and husk.

It's an anti-inflammatory agent known for its antioxidant and antibacterial properties.

The EWG sees it as a 1-2. Relatively safe.

Glyoxysomal catalase

Pumpkin contains this enzyme, which has a smaller molecular structure than most fruit enzymes, making it easier to penetrate the skin surface. It destroys free radicals, which helps prevent premature aging.

Papain

Unripe papaya contains it.

Papain is known for removing damaged keratin from the skin, brightening and evening the complexion. Papaya's enzyme papain helps reduce inflammation, age spots and smooth skin texture.

The EWG sees it as a 1-2. Relatively safe.

Fermented Pomegranate Enzymes multitasks as a potent skin brightener and powerful antioxidant with tyrosinase-inhibiting qualities

Actinidin

Actinidin enzyme is in kiwi, mango, papaya, pineapple, and banana.

It exfoliates dead surface skin cells and dirt on the skin's top.

This enzyme moisturizes the skin and keeps it supple.

The EWG approves it and rates it as a 1.

Ficin

Ficin is most commonly found in figs and works well for removing scars and pigmentation.

It also makes your skin visibly softer and smoother.

Catecholase

Potatoes have catecholase, which exfoliates mildly.

Comparison of enzyme and acid peels

Enzyme and acid peels are effective exfoliants that enhance skin brightness and smoothness, reduce age spots, and better prepare the skin to absorb moisturizer nutrients. Here's a comparison of their effects and properties:

Exfoliation and cell turnover

Enzymes break down and dissolve the dead keratin protein in the topmost layer of the skin, facilitating skin renewal.

Acids dissolve the glue that attaches dead skin cells and penetrate the pores, promoting cell turnover.

Suitability for skin types

Enzymes: Suitable for oily, acne-prone, sensitive, scarred and combination skin. Their antibacterial properties help unclog pores and prevent blackhead formation.

Acids (AHAs/BHAs)

It is effective for oily, acne-prone, scarred and combination skin. Still, it can be too intense for sensitive skin or those with darker skin tones, often requiring a period of acclimatization.

Effect on skin

Enzymes: Slightly dilate pore openings, enhancing skincare absorption.

Acids: Work best at low pH to denature the protein between skin cells, loosening their connection.

Additional benefit

Enzymes have anti-inflammatory properties that soothe the skin, which are beneficial for conditions like redness, inflammation, and possibly rosacea. Research indicates enzymes like papain and bromelain have promising anticancer properties due to their ability to break down cell walls.

Acids require careful pH management to avoid disrupting the skin's acid mantle barrier. For optimal exfoliation, gradually start from lower concentrations (2-4%) and increase glycolic acid levels over time.

Speed and results

Enzymes act quickly, making them ideal for consumers seeking instant, visible results. They also offer antioxidant benefits and can be formulated to boost collagen production.

Acids: Work effectively at low pH but can cause irritation or inflammation in sensitive and darker skin tones if not used properly.

Safety and recommendations

Enzymes are derived from natural sources like fruits and generally do not contain aggressive ingredients. However, consulting with a physician before use is recommended.

Acids: Gradually adjusting concentrations should be taken to avoid skin irritation.

Overall benefits

Both enzymes and acids allow serums and moisturizers to penetrate the skin more deeply, enhancing their effectiveness.

Both have anti-inflammatory properties that help soothe the skin and reduce redness or inflammation.

Peeling effect

Enzyme peeling occurs invisibly.
Acid Peels cause sunburn peeling to occur a day or so after application.
Avoid sun tanning, tanning beds, laser, or Intense Pulse Light, as well as waxing hair removal sessions for both acids and peels.
Contraindication of Enzymes
Avoid AHA peels when using retinol products
Avoid Accutane or other medications altogether.
Pregnant and breastfeeding clients can use enzymes products to get glowing skin.
Green Raw papaya contains the enzyme papain. They drain the milky white latex from the flesh to extract the papain. Latex allergy or other ingredients in enzyme-based products are one of its few contraindications or side effects.
Avoid using on microneedled, broken, or irritated skin.

Conclusion

Maximizing Skin Renewal Safely AHAs and BHAs are powerful exfoliators that dissolve the dead skin cell bonds, promoting cell turnover, smoother texture, and a brighter complexion. Proper formulation, correct pH balancing, and adherence to Health Canada's 10% concentration cap are key to mitigating these risks. Consumers should look for compliant warning labels and consider Bio-Based or USDA Certified Glycolic Acid product labelling to ensure both regulatory compliance and the absence of petrochemical contaminants.

For a natural, effective alternative, enzyme-based exfoliators promote cell turnover with fewer side effects. These exfoliators can break down proteins into smaller peptides, including collagen peptides, which act as signal peptides to stimulate fibroblasts to produce new collagen and elastin fibres, essential for skin structure and elasticity. Importantly, encouraging your skin to generate its own peptides naturally is often more beneficial than relying solely on peptide-containing products, as these endogenous peptides integrate seamlessly into your skin's repair mechanisms.

By understanding the mechanisms, benefits, and potential risks of chemical and enzyme-based exfoliators, individuals can make informed choices to maintain healthier, more radiant, and resilient skin, while supporting natural collagen and elastin production.

Under Health Canada’s Food and Drugs Act, cosmetic products are strictly intended for cleansing, improving, or altering the complexion and appearance of the skin; they are not authorized to diagnose, treat, cure, or prevent any disease or medical skin condition.

This information is for educational purposes only. Do your own research.

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Read more from Ida Fanelli

Ida Fanelli, Aesthetician, Reflexologist & IPL & Dolphin MPS Technician

Ida is a dedicated wellness professional and certified aesthetician (Marvel School of Beauty), providing personalized, home-based services since 1994. A certified reflexologist since 1993 (D'Arcy Lane Institute), she has integrated energy therapies and Ion Cleanse foot wellness sessions since 1998. In 2012, she became a certified Sharplight IPL Technician for skin rejuvenation and pigmentation correction, and in 2019 earned a specialized certification from the Center for Pain and Stress Research, using the Dolphin Neurostim system for Microcurrent Point Stimulation to support scar tissue release, skin rejuvenation, and pigmentation lightening. Ida is deeply committed to continuing education in complementary health to provide accessible, high-quality care. She also brings 12 years of experience as a hospital laboratory technologist in Microbiology and Biochemistry to her meticulous practice.

Legal Disclaimer:

Educational Purposes Only: The information provided in this article is for educational, informational, and entertainment purposes only. It is not intended as, and should not be taken as, professional medical advice, diagnosis, or treatment for any skin condition.
Regulatory Compliance: References to ingredient concentrations and safety parameters reflect standard cosmetic guidelines, including Health Canada’s Cosmetic Ingredient Hotlist. Cosmetic formulations do not alter cellular or organic functions and are not substitutes for therapeutic or dermatological treatments.
Individual Variance: Always consult with a qualified dermatologist, physician, or certified skincare professional before introducing new active acids or high-strength chemical/enzyme peels into your routine, especially if you are pregnant, nursing, have sensitive skin, or have an underlying health condition. Always perform a localized patch test prior to full application.

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