Lactic acid, a chemical exfoliant derived from the fermentation of lactose (a carbohydrate in milk), is naturally present in the skin, produced by beneficial bacteria within the skin’s microbiome. It is categorized as a post-biotic and can also be found in certain foods, including sugar cane and wine, imparting a characteristic sour taste associated with fermentation.The use of lactic acid in cosmetics dates back to ancient Egypt, where Cleopatra famously bathed in donkey milk rich in this AHA to achieve soft skin. AHA compounds, being water-soluble organic acids, are recognized for their skin-rejuvenating properties by promoting cell renewal.In skincare formulations, lactic acid can be sourced from either synthetic or plant origins. At Typology, the lactic acid used in our gentle peeling serum is obtained through the fermentation of corn sugar with specific bacteria, such as Lactobacillus.

When applied topically, lactic acid provides a multitude of benefits:Exfoliation: It aids in the removal of dead cells that clog pores, smoothing the skin's texture. By dissolving intercellular bonds, it promotes cellular renewal, reviving dull complexions and helping to prevent blackheads. Hydration: Lactic acid enhances the skin’s natural hydration levels, making it an effective moisturizer. Pigmentation and Fine Lines: It assists in diminishing pigmented spots and softening fine lines. Scarring and Redness: Lactic acid can lighten scars and reduce post-inflammatory redness, particularly from acne.In cosmetic formulations, lactic acid also acts as a pH regulator, ensuring a slightly acidic environment suitable for the epidermis.

Lactic acid is primarily employed in dandruff treatments, alleviating itching and controlling oily dandruff. It helps maintain a healthy scalp by preventing hair follicle blockage. Additionally, its moisturizing properties aid in preventing hair fiber dryness and split ends.

Lactic acid is considered gentle compared to other AHAs, making it suitable for sensitive skin types seeking mild exfoliation. Due to its larger molecular size, it penetrates less deeply into the skin, resulting in reduced irritation compared to glycolic acid. This makes it an excellent alternative for those who may not tolerate glycolic acid well.However, lactic acid can still cause side effects, such as increased sensitivity to sunlight and potential irritation, which may present as itching, burning, or redness. Consequently, European regulations recommend a maximum concentration of 10% for lactic acid in cosmetic products.Because it increases photosensitivity, it's advisable to apply lactic acid in the evening and use a broad-spectrum sunscreen during the day and in the following days. Always conduct a patch test before incorporating a lactic acid product into your routine; apply a few drops to the inner arm or back of the hand and wait 24 hours. If any reaction occurs, refrain from using the product on your face.Important Note: Avoid lactic acid treatments if you are currently using retinoid-based products.

Smith W. P. Epidermal and Dermal Effects of Topical Lactic Acid. Journal of the American Academy of Dermatology (1996).Sachdeva S. Lactic Acid Peeling in Superficial Acne Scarring in Indian Skin. Journal of Cosmetic Dermatology (2010).Rathi S.K. Treatment of Acne Vulgaris: The Current Landscape. Indian Journal of Dermatology (2011).