Alpha Hydroxy Acids (AHA) and Their Use in Dermocosmetics

Alpha hydroxy acids (AHAs) are organic compounds widely used to exfoliate, hydrate, and improve the appearance of the skin. They are among the most studied active ingredients in dermocosmetics and are used both for blemish-prone skin and in anti-aging treatments.

Let’s look at what they are, how they work, which concentrations are used, and what precautions to take.

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What Are Alpha Hydroxy Acids?

AHAs are organic acids characterized by a carboxyl group adjacent to a hydroxyl group on the neighboring carbon. The most common include:

• Glycolic acid: found in sugar cane, it has the smallest molecule and is therefore the most penetrating;
• Lactic acid: derived from fermentation, it is gentler and has hydrating properties;
• Mandelic acid: extracted from almonds, it has the largest molecule and therefore provides the most gradual action;
• Citric acid: found in citrus fruits, it is also often used as a pH regulator.

These ingredients can be naturally extracted or synthesized, and are used at different concentrations depending on the application.

The main difference compared with BHAs, such as salicylic acid, lies in their solubility: AHAs are water-soluble and work mainly on the surface, while BHAs are oil-soluble and can penetrate the pore. This is why AHAs are the preferred choice for uneven texture and dull complexion, while BHAs are better suited to blackheads and clogged pores.

How AHAs Work

AHAs work on several levels, improving the appearance of the skin through three main mechanisms.

1. Exfoliation: they reduce cohesion between the cells of the stratum corneum, promoting cell renewal.
2. Hydration: they increase the skin’s ability to retain water, improving elasticity and firmness. Lactic acid, in particular, is part of the skin’s Natural Moisturizing Factor.
3. Collagen support: in vitro studies have observed increased collagen production in skin fibroblasts.

These effects make AHAs useful in anti-aging treatments, for improving skin texture, and for managing blemish-prone skin.

Cosmetic Applications

Blemish-Prone and Acne-Prone Skin

AHAs, particularly glycolic acid, help improve the appearance of acne-prone skin by promoting cell turnover and helping prevent clogged pores. Results become noticeable over several weeks of consistent use.

Skin Aging

AHAs are known for their effects on photoaging. At higher concentrations, reserved for professional treatments, they help:

• reduce the appearance of fine lines;
• improve complexion uniformity and discoloration;
• support epidermal thickness.

Concentrations, Safety, and Precautions

AHAs are safe to use when the recommended concentrations are respected:

• up to approximately 10% in cosmetics for home use, with a pH that is not too low;
• higher concentrations are reserved for professional treatments performed by qualified professionals.

The most common side effects are irritation, redness, and a mild tingling sensation. AHAs increase the skin’s sensitivity to the sun: during treatment, it is essential to apply adequate sun protection every morning. If you have a skin condition, consult a dermatologist.

How to Incorporate AHAs into Your Routine

1. Start gradually: begin with low concentrations and one or two applications per week to allow your skin to adjust.
2. Apply in the evening: the skin is more sensitive to the sun during treatment.
3. Do not layer too many active ingredients: avoid combining AHAs and retinoids in the same application, especially at first.
4. Always use sun protection: this is what makes everything else worthwhile.

AHAs in LeLang Products

We chose mandelic acid as our reference AHA because, having the largest molecule, it penetrates more slowly and evenly: it is the best-tolerated alpha hydroxy acid, including for reactive skin.

Mandelic Enzymatic Soft Peel combines the action of mandelic acid with that of two enzymes, papain and bromelain, for gentle exfoliation you can perform at home.

You can also find LeLang products at our partner pharmacies throughout Italy.

Conclusion

AHAs are a cornerstone of dermocosmetics thanks to their versatility. Their ability to improve texture, hydration, and radiance makes them a key ingredient in treatments for blemish-prone skin and photoaging. For optimal results, choose products with concentrations and pH levels suited to your needs.