Lactic Acid (LA) is one of the most well-known alpha-hydroxy acids (AHAs), derived from natural and biodegradable sources, and has been employed by the cosmetic industry for the treatment of issues related to pigment, dry/scaly skin, and natural wrinkling/fine-lines that occur during the aging process. Due to its long history and frequency of use, it has been studied extensively in order to determine its efficacy and safety.
Lactic Acid is derived from sour milk or bilberries, and has been used for anti-aging, acne treatments, and dry skin for time immemorial; it traces its first origin in recorded history back to Cleopatra, who bathed in it to maintain a youthful appearance.1
It is a low-molecular-weight organic acid which was first identified in 1780 by Swedish Chemist Carl Wilhelm Scheele.2 Lactic Acid became known for specific and unique benefits for skin that are only associated with the alpha-hydroxy acid group.2 The other most popular alpha-hydroxy acid, Glycolic Acid, did not enter the market until 1990, whereas Lactic Acid has been in use since 1975.3
For the use of the cosmetic and dermatological industry, it tends to be used in isolated or synthetic forms (in order to reduce the risk of side-effects), and is normally injected or applied topically in order to achieve the most benefit for epidermal disorders.
It is best to explore Lactic Acid in reference to its effects on pigmentation, dry skin, and wrinkling, as the specific mechanisms LA utilizes work on the three simultaneously -- but the way the conditions benefit from its application can differ.
In the function of pigmentary-issue resolution, Lactic Acid works in two main ways: through the inhibition of the tyrosinase enzyme responsible for the production of melanin and by causing an accelerated rate of regeneration of the skin-barrier, allowing areas damaged by UV radiation to be replenished and pigment damage to be reduced.6
The tyrosinase enzyme is a primary part of melanin’s production and, when there are free radicals from UVA and UVB rays present in the skin, it can be forced into an over-productive state that results in age spots, post-inflammatory hyperpigmentation (PIH), and melasma that are associated with sun damage and aging.6
By inhibiting tyrosinase upon application (either topical or injectable), Lactic Acid is able to prevent this formation from occurring -- but only to the point where it is beyond the natural protective barrier needed for sun protection.6
The other way that Lactic Acid is able to assist with pigmentation is through a regeneration of the epidermis (called epidermal remodelling), which is regulated by a process called desquamation (the shedding of dead skin cells).1 This process is controlled by cells called cytokines, signal cells released by other cells/proteins in the skin, that let the body know when to refresh the skin barrier with new skin cells.7
Lactic Acid is able to manipulate the secretion of cytokines and forces a more-rapid regeneration of skin cells in the areas being treated -- allowing a new layer of fresh skin cells to replace the old, over-pigmented ones8. This accelerates the desquamation process, and while doing so, LA also decreases the thickness of the epidermis by removing the adhesive properties of corneocytes (the far-outer layer of skin cells that are the first defense of the skin)1.
The new layer of epidermis that follows the desquamation of the old one allows new, normally-pigmented, skin to take its place. This mechanism of recycling the older barrier also provides refreshment to areas suffering from dry skin and wrinkling -- and increases the thickness of the skin which helps to cover facial lesions.5
The other major property of Lactic Acid that allows it to specifically help with areas struggling with dryness, or subsequent wrinkling from a lack of moisture, is its role as an alpha-hydroxy acid. AHAs are known for their ability to promote increased hyaluronic acid absorption in the epidermis and dermis, which is necessary for the retention of moisture in the skin.9
Topical AHAs and LA also create increased collagen production in the skin through the use of inflammation, which forces a natural healing reaction that restores elasticity to the skin.2 Wrinkles and fine-lines are generally a result of a loss of collagen and elasticity through aging and sun-damage, and Lactic Acid is able to directly reduce those effects when it forces the healing factor to target specific areas by causing controlled inflammation.
Through Lactic Acid’s many properties, such as: its ability to cause epidermal remodeling, the inhibition of tyrosinase, and the retention of moisture by stimulating the release of hyaluronic acid, it is able to treat pigmentary issues, areas suffering from dry skin, and wrinkles with a high efficacy.3
Multiple studies have explored the various benefits and results of applying Lactic Acid with highly satisfactory results.5,8.9,10 In comparison to other treatments, Lactic Acid has proven to be superior in the treatment of hyperpigmentation, sallowness/hollowness, and roughness of the skin.10
In differing concentrations of Lactic Acid (ranging from 2% - 70%), it has also been used to treat other conditions such as: acne, ichthyosis, keratoses, warts, psoriasis, photoaged skin, and more. The measured improvements for each were decreases in skin roughness, discoloration, protein build-ups, pigmentary issues, and skin-elasticity.8
Volume lost in the aging process has been successfully restored (in part) by the application of Poly-L-Lactic Acid (a synthetic derivative of Lactic Acid), which proved to be able to restore a youthful contour to parts of the face struggling from skin laxity or wrinkling.11
Lactic Acid is available in many different cosmetological and dermatological products and services and, as each one uses differing concentrations depending on the treatment required, the time it takes to work will be different for each person using it and the severity of the condition to be treated.
It is best to follow the product instructions of any cosmeceutical containing Lactic Acid to ensure best results within the anticipated timeline provided by the manufacturer.
Lactic Acid is renowned for its ability to treat epidermal issues with very low side-effects. As with most cosmetic acids, the most common side-effect is increased sun sensitivity.2 Other side-effects noticed during the studies was mild irritation/redness of the skin, but those were observed to decrease with continued use.9
Salicylic Acid is a part of the beta-hydroxy acid (BHA) group, which is a type of acid that differs in penetrative abilities deeper into the epidermis. Although they are both naturally-derived acids, their disbursement to treat skin conditions tends to be different due to their innate properties.
While AHAs tend to be used for the epidermis due to their inability to penetrate oily barriers, BHAs are able to penetrate those same barriers with a high efficacy. This makes SA more suitable for treating issues within the dermis (the deeper layer underneath the epidermis), especially blackheads and oily/enlarged pores. As it is a more intensive form of acid, it is not generally used to treat the more superficial issues that LA is better suited for.1
1. Castillo, D. E., & Keri, J. E. (2018). Chemical peels in the treatment of acne: patient selection and perspectives. Clinical, cosmetic and investigational dermatology, 11, 365.
2. Alsaheb, R. A. A., Aladdin, A., Othman, N. Z., Malek, R. A., Leng, O. M., Aziz, R., & Enshasy, H. A. E. (2015). Lactic acid applications in pharmaceutical and cosmeceutical industries. J. Chem. Pharm. Res, 7(10), 729-735.
3. Harding, C. R., & Rawlings, A. V. (2005). 18 Effects of Natural Moisturizing Factor and Lactic Acid Isomers on Skin Function.
4. Graf, J. (2005). Anti-aging skin care ingredient technologies. In Cosmetic dermatology (pp. 17-28). Springer, Berlin, Heidelberg.
5. Schierle, C. F., & Casas, L. A. (2011). Nonsurgical rejuvenation of the aging face with injectable poly-L-lactic acid for restoration of soft tissue volume. Aesthetic surgery journal, 31(1), 95-109.
6. Chen, M. J., Liu, J. R., Sheu, J. F., Lin, C. W., & Chuang, C. L. (2006). Study on skin care properties of milk kefir whey. Asian-australasian journal of animal sciences, 19(6), 905-908.
7. Hänel, K., Cornelissen, C., Lüscher, B., & Baron, J. (2013). Cytokines and the skin barrier. International journal of molecular sciences, 14(4), 6720-6745.
8. Kornhauser, A., Coelho, S. G., & Hearing, V. J. (2010). Applications of hydroxy acids: classification, mechanisms, and photoactivity. Clinical, cosmetic and investigational dermatology: CCID, 3, 135.
9. Tran, D., Townley, J. P., Barnes, T. M., & Greive, K. A. (2015). An antiaging skin care system containing alpha hydroxy acids and vitamins improves the biomechanical parameters of facial skin. Clinical, cosmetic and investigational dermatology, 8, 9.
10. Stiller, M. J., Bartolone, J., Stern, R., Smith, S., Kollias, N., Gillies, R., & Drake, L. A. (1996). Topical 8% glycolic acid and 8% L-lactic acid creams for the treatment of photodamaged skin: a double-blind vehicle-controlled clinical trial. Archives of dermatology, 132(6), 631-636.
11. Beer, K., & Beer, J. (2009). Overview of facial aging. Facial plastic surgery, 25(05), 281-284.
12. Ali, S. M., & Yosipovitch, G. (2013). Skin pH: from basic science to basic skin care. Acta dermato-venereologica, 93(3), 261-269.
13. Grove, G., & Zerweck, C. (2004). An evaluation of the moisturizing and anti-itch effects of a lactic acid and pramoxine hydrochloride cream. CUTIS-NEW YORK-, 73(2), 135-139.