By Liane Scior
Director of Education
In today’s clinical skincare landscape, chemical peels remain one of the most effective tools for rejuvenation, when performed with precision and respect for the skin’s natural barrier. Yet more clients than ever are presenting with fragile, sensitised, or over-treated complexions, making a “one-formula-fits-all” approach risky and outdated.
The new standard in professional peeling is personalisation: understanding how each acid works, what the skin truly needs in its current state, and how to support every treatment with barrier-protective ingredients that deliver visible, lasting results without compromise.
Why Barrier Health Comes First
The stratum corneum acts as the skin’s first line of defence, maintaining hydration, regulating pH, and protecting against microbial invasion. When this barrier is disrupted, the skin’s tolerance to exfoliating acids decreases significantly. Peels that were once easily tolerated can now cause inflammation, prolonged erythema, or post-inflammatory pigmentation.
By prioritising barrier restoration, through pre-peel homecare enriched with ceramides, panthenol, niacinamide, and calming antioxidants, we ensure that the skin is hydrated, balanced, and resilient enough to respond positively to chemical exfoliation. Once the barrier is stable, the peel can perform its rejuvenating function safely and effectively.
Understanding the Acids: Selecting the Right Tool for Each Condition
Each acid used in professional peels has a unique molecular structure, penetration rate, and action within the skin. Understanding these properties allows you to select the right acid, or combination, to target specific concerns while remaining barrier conscious.
Glycolic Acid – Refining and Rejuvenating
Derived from sugar cane, Glycolic Acid is the smallest alpha-hydroxy acid (AHA), allowing it to penetrate rapidly to stimulate cellular turnover and collagen formation. It’s highly effective for photo-aged, thickened, or dull skin. However, because of its potency, it should only be used on well-prepared, healthy skin barriers to avoid excess irritation.
Lactic Acid – Hydrating and Gentle Brightening
Lactic Acid, naturally found in fermented milk, has larger molecules than Glycolic, creating a slower, more controlled exfoliation with added humectant benefits. This makes it suitable for dehydrated, mature, or mildly sensitive skin, helping to refine texture while supporting moisture retention.
Phytic Acid – Clarifying and Pigment-Regulating
Phytic Acid, derived from rice bran, provides mild keratolytic action while inhibiting tyrosinase activity — a key enzyme in melanin production. Its antioxidant and brightening properties make it ideal for uneven tone, post-inflammatory pigmentation, or dull complexion, and its gentle activity respects more delicate skins.
Hexylresorcinol – Illuminating and Melanin-Modulating
Although technically not an acid, Hexylresorcinol functions as a pigment regulator up to four times more effective than Hydroquinone. It’s an excellent choice alongside exfoliating acids in treating hyperpigmentation, melasma, or sun-induced discoloration without compromising barrier resilience.
Enzymes (Acto-Zyme™) – Natural and Balancing Exfoliation
Enzymatic exfoliants like Acto-Zyme™ use proteolytic enzymes to digest surface keratin and reduce roughness. Since they act primarily on dead-cell bonds rather than living tissue, they’re suited to impaired or reactive skins that cannot yet tolerate acids. They’re a valuable bridge between barrier restoration and an eventual acid peel program.
Enhancing Peels with Supportive Actives
The effectiveness and tolerance of a peel can be elevated by pairing acids with nurturing or corrective active agents. These ingredients don’t simply add benefits, they balance and buffer the activity, creating a more tailored and intelligent skin response.
Retinol (Vitamin A): A cell-renewal accelerator that enhances epidermal turnover and collagen synthesis. Best paired with stronger acids once the barrier is intact, for advanced anti-aging or restructuring treatments.
Vitamin C (Ethyl Ascorbic Acid): A stable antioxidant that brightens, protects, and co-factors collagen synthesis. Excellent for mature, sun-damaged, or smoker’s skin when combined with Lactic or Phytic acids.
Collagen Polypeptides: Promote elasticity and hydration, helping to cushion and protect post-peel skin and maintain suppleness.
Zinc PCA: Regulates sebum, has antimicrobial and anti-inflammatory benefits, and supports wound healing, ideal for acne-prone or barrier-impaired clients using acid blends.
Peptides (e.g., Palmitoyl Tetrapeptide-5, Panthenol): Encourage repair and calm sensitivity, making them valuable for skin recovering from frequent professional treatments.
Each of these actives transforms traditional exfoliation into a restorative experience, one that treats not only the surface but the function of the skin beneath.
What about pH and percentages, how important are they?
pH and percentages are critical in chemical peels, they directly control penetration depth, exfoliation strength, and skin safety, especially for barrier-compromised clients.
pH: The Gatekeeper of Peel Strength
Skin's natural pH sits around 4.5–5.5, which maintains barrier function by regulating lipid production and enzyme activity. Peel pH determines efficacy:
Low pH (1–3): Superficial/medium peels (e.g., glycolic at pH 2–3) drive deeper exfoliation but risk disrupting the barrier if the skin isn't prepped.
Moderate pH (3–4): Balanced for most professional use, like salicylic peels, allowing controlled action without excessive irritation.
Higher pH (4.5–5.5): Gentler options (e.g., LHA or enzyme peels) work in harmony with skin's pH for sensitive or compromised barriers.
Wrong pH can lead to sensitivity, dryness, or inflammation by shifting skin's acid mantle.
Percentages: Precision for Results and Safety
Acid concentration (% by weight) dictates potency:
Low (5–15%): Entry-level for beginners or sensitised skin, hydrates while lightly resurfacing (e.g., lactic acid).
Medium (20–30%): Standard professional strengths for acne/pigmentation (e.g., salicylic 20–30%).
High (35%+): Deep action for advanced concerns, but only on resilient skin with strict protocols.
Higher % = faster results but greater barrier stress; always titrate based on client tolerance and pre-peel barrier health.
The Art of Customisation
Successful peeling now relies less on strength and more on strategy. Combining acids of complementary strengths, such as pairing Lactic Acid for hydration with Phytic Acid for pigmentation, allows for layered, condition-specific treatment without overwhelming the skin’s defences. Adding barrier-building actives ensures recovery begins immediately.
The message is simple: when the skin’s barrier is prioritised, the results of every peel become more predictable, more comfortable, and more sustainable for long-term rejuvenation.
Barrier protection isn’t just good practice; it’s the key to modern professional peeling.
Medicalia peels represent the next generation of professional exfoliation, empowering skin therapists to truly customise treatments for each client’s unique skin profile and barrier status. Unlike traditional one-strength-fits-all formulas, Medicalia blends precisely calibrated acids, like glycolic for rapid renewal, lactic for hydration, phytic for pigment control, and hexylresorcinol for superior brightening, with targeted actives such as retinol, collagen polypeptides, vitamin C, zinc PCA, peptides, and enzymatic Acto-Zyme™.
This intelligent synergy allows you to dial in the exact pH (typically 2.5–4.5 for controlled penetration) and percentage strengths (10–30%+ depending on concern), tailoring depth and downtime while buffering irritation for compromised barriers.
The result? Safer, more predictable outcomes, refined texture, even tone, and resilience, that align with modern demands for personalised, barrier-first skincare.
