By Dr Naomi Mackle
Dermatology Specialist & Medical Director, Adare Dermatology ClinicsChemical exfoliation is one of the most effective ways to transform skin texture, boost radiance, and manage conditions like acne and hyperpigmentation. At the heart of this process are Alpha Hydroxy Acids (AHAs). While glycolic acid tends to grab the headlines, it is far from your only option. Understanding how different AHAs function—and how to integrate them safely into your regime—is key to achieving smoother, healthier-looking skin without causing unnecessary irritation.
What Are AHAs and How Do They Work?
AHAs are water-soluble acids that dissolve the bonds binding dead cells to the surface of the stratum corneum. By accelerating this natural shedding process, they help prevent blocked pores and allow brighter, fresher skin to reflect light more evenly.
The Three Main AHAs
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Glycolic Acid: The smallest molecular size allows it to penetrate deeply and quickly. It is the most potent and effective AHA, though also the most likely to cause tingling or irritation.
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Lactic Acid: Possesses a larger molecule for gentler surface action. Crucially, it doubles as a humectant, helping dry or rough skin attract and retain moisture.
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Mandelic Acid: Featuring a much larger molecular structure, it absorbs slowly and evenly. This makes it ideal for sensitive skin and deeper skin tones, where aggressive irritation can trigger post-inflammatory hyperpigmentation.
Note: Other AHAs like citric, malic, and tartaric acids play secondary roles in formulations. For extremely reactive skin, Polyhydroxy Acids (PHAs) offer an even gentler alternative.
Why Combine Acids?
Formulations often blend acids—such as pairing glycolic with mandelic acid. This approach provides multi-depth exfoliation, leveraging glycolic’s fast surface action and mandelic’s slow absorption without needing higher, harsher concentrations of a single acid.
Practical Application: How to Use AHAs Safely
To get the best results from chemical exfolation while protecting your skin barrier, follow a sensible, phased approach:
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Ease In Gradually: Start using your AHA product three days a week, increasing frequency by one day each week as tolerated.
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Use Short-Contact Therapy for High Potency: When introducing stronger leave-on treatments (such as peel-style gels), apply for just 30 seconds before washing off, following immediately with a hydrating moisturizer.
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Protect Sensitive or Young Skin: If using a glycolic cleanser on delicate or adolescent skin, alternate days with a gentle, non-active cleanser.
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Prioritise Barrier Repair: Exfoliation must be balanced with restoration. Always follow up with a barrier-supporting moisturizer—adding a hydrating serum like Vitamin B5 if your skin feels compromised, dry, or prone to conditions like eczema.
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Apply Daily Sunscreen: AHAs increase photosensitivity. Broad-spectrum SPF is non-negotiable every morning during treatment.
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Manage Irritation Promptly: If red or reactive, halt usage until the skin settles, then reintroduce at a lower frequency.
Suitability: Who Should Use Them (and Who Should Pause)
| Ideal Candidates | Proceed with Caution |
| • Pigmentation & sun damage | • Rosacea: Avoid glycolic cleansers; opt for gentle hydrating or PHA formulas. |
| • Mild-to-moderate acne | • Eczema or Compromised Barrier: Deep-penetrating acids can aggravate inflammation. |
| • Rough, uneven skin texture | • Recent Procedures: Avoid actives for several days following peels or laser therapy. |
| • Seborrhoeic dermatitis | • Active Regimes: Do not start a retinoid simultaneously with a new AHA. |
Special Considerations:
What the Evidence Shows
Decades of dermatological data support the efficacy of AHAs:
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Glycolic Acid: Proven in clinical trials to improve acne, hyperpigmentation (including melasma alongside combination therapies), texture, and fine lines. Long-term use encourages collagen support in deeper layers.
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Lactic Acid: Firmly established for hydrating and smoothing rough, dry skin.
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Mandelic Acid: Demonstrates clear benefit for acne and pigmentation with a lower incidence of side effects compared to glycolic acid.
Trial Limitations: Many clinical studies evaluate high-strength in-clinic chemical peels rather than over-the-counter home formulations, and exact results vary depending on product pH and vehicle formulation.
Expected Timelines
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Texture: Immediate smoothing effect within days.
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Acne: Progressive reduction in breakouts over consistent weeks of use.
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Pigmentation: Gradual lightening over several months when combined strictly with daily SPF.
How We Formulate: The REFORM Skincare Range
At REFORM, we utilise AHAs across our range because their mechanisms are reliable, well-tested, and address the primary concerns presented in our clinics.
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Glycolic Acid Foaming Cleanser: Designed for daily cleansing to manage oiliness, seborrhoeic dermatitis, mild acne, and dullness.
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Repair and Renew Gel: Combines glycolic and mandelic acids to act as a gentle home-peel gel for photorejuvenation and clearing blocked pores.
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Skin Barrier Repair Cream: Pairs lactic acid with 10% urea to focus on intense hydration for dry, rough skin, eczema, and psoriasis.
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Everyday Moisturiser & Vitamin B5 Gel: Formulated specifically to repair the skin barrier alongside active exfoliation.
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Mineral SPF 30 / SPF Mist: Essential daily broad-spectrum sun protection required during AHA use.
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Disclosure: Dr Naomi Mackle is the founder of REFORM Skincare, the in-house brand of Adare Dermatology Clinics. REFORM products are recommended where clinically appropriate. This article is for general informational purposes and does not replace an individual medical consultation.*
