Spotlight on...LACTIC ACID

Lactic acid is an alpha hydroxy acid commonly used in skincare. Ellen Cummings quizzes the experts to find out more about the science behind the acid and how it can be used in salon

How does lactic acid work?

Lactic acid is commonly used in topical skincare, and these days it’s usually synthetically made in a lab but was traditionally created as a natural by-product of plant and dairy fermentation. Lactic acid is an alpha hydroxy acid (AHA) which has a number of benefits for the skin, including gentle exfoliation properties.

Rebecca Jones, trainer and ambassador for Noon Aesthetics, says, “Lactic acid causes the breakdown of the desmosomes (skin-binding enzymes) to induce surface cells to be released, stimulating the exfoliation process. The deeper layer of skin is stimulated to increase synthesis of collagen and glycosaminoglycans (the skin’s water carriers).”

Lactic acid has a larger molecule size than some of the other AHAs such as glycolic acid, so it’s gentler and can’t penetrate as far into the skin. This means its exfoliating effects are mainly on the skin’s surface. Dr Catharine Denning, a cosmetic doctor who runs a regular clinic from The Light Centre in London, says, “Lactic acid breaks the bonds between dead skin cells on the surface of the epithelium, which helps to shift superficial pigmentation (in high strengths and at a lower pH).”

How should it be used?

Lactic acid is a great treatment for pigmentation and uneven skin tone as well as dry, dehydrated and dull skin. It can also reduce the appearance of fine lines and help stimulate ceramide formation to strengthen the skin’s barrier function. Denning adds, “Its antioxidant properties help mop up free radicals and heavy metals that may come into contact with the skin, protecting it against DNA damage.”

In addition, there is scientific evidence to show that lactic acid can boost the skin’s vitality. Cigdem Kemal Yilmaz, a chemical engineer, skincare formulator and the founder of Skin Masterclass, cites a 1996 study by WP Smith. “It showed that treatment with 12% lactic acid resulted in increased epidermal and dermal firmness and thickness, and clinical improvement in skin smoothness and the appearance of fine lines and wrinkles. No dermal changes were observed after treatment with 5% lactic acid; however, similar clinical and epidermal changes were noted.”

Yilmaz concludes, “The clinical evidence indicates that the topical application of lactic acid is effective for depigmentation and improving the roughness and mild wrinkling of the skin caused by environmental photodamage.”

How should it be used?

Because lactic acid is a gentle exfoliant, it can be found in many home-use skincare products including cleansers, toners and serums – so there are plenty of ways for clients to include it in their routines.

“In topical skincare, lactic acid can be used as part of the cleansing step or following a cleanser as a standalone ingredient up to twice a day,” says Denning. “Clients can follow it with other leave-on products, and, as always, finish with sunscreen during the day, or moisturiser at night if they need it.”

At home, lactic acid can also be used in a stronger formulation as a weekly wash-off, mild peel, but for greater effect clients can visit a beauty professional for a more intense peel. Lactic acid also can boost the effects of other salon treatments. “It works well to complement aesthetic procedures such as needling and injectables. Although you would not perform the treatments together, their benefits work in harmony to achieve results,” comments Jones.

While it’s important not to overprocess the skin by using too many exfoliants and actives at the same time, lactic acid can be safely layered with most skincare ingredients. Denning says, “It is okay to pair or alternate lactic acid with other forms of exfoliant such as salicylic acid if you find your skin’s pores tend to clog or are blemish prone.”

Hyaluronic acid is another great pairing to boost the skin’s hydration, while Yilmaz shares her preferences: “Personally, I love layering lactic acid with vitamin C (ethyl ascorbic acid), amino acids, panthenol, and green tea extract.”

Are there any contraindications?

If a client has very sensitive skin then lactic acid can be irritating, and Denning advises against using it on clients who suffer from eczema, psoriasis and rosacea – although she says it’s safe for use with pregnant and lactating clients in a concentration of 5% or less.

Issues could also occur if the lactic acid used in skincare products is derived from dairy and clients have a dairy allergy or intolerance – so it’s important to check the provenance of your lactic acid products and to carry out a pre-treatment consultation with clients to ascertain any potential contraindications. It’s also not recommended to layer lactic acid with retinoids because this can irritate skin.