Glycolic acid and niacinamide: a beneficial combination for the skin?

The glycolic acid and niacinamide are among the most studied and most widely used actives in cosmetics, each acting via distinct but complementary biological mechanisms. The glycolic acid primarily acts on corneocyte cohesion, the cells of the stratum corneum, by reducing it, which accelerates the desquamation process and thus improves tone uniformity and refines skin texture. The niacinamide on the other hand has a broader range of action. It strengthens the barrier function of the skin by increasing ceramide synthesis, which improves hydration and reduces transepidermal water loss. It also modulates the inflammatory response by decreasing pro-inflammatory cytokine production and limits hyperpigmentation by reducing melanosome transfer from melanocytes to keratinocytes. Another advantage of niacinamide : it is suitable for all skin types, even the most sensitive.

It is entirely possible to combine glycolic acid and niacinamide within a single cosmetic formula. However, it is not recommended to layer two separate products, because glycolic acid requires an acidic pH (≈ 3–4) to exert its exfoliating effect, while niacinamide serums are formulated at a more neutral pH (≈ 5–7).

Several recent studies highlight that the glycolic acid/niacinamide combination may be beneficial for reducing blemishes while strengthening the skin barrier. A study conducted with 25 subjects evaluated a formulation combining several active ingredients, including glycolic acid and niacinamide, in the management of mild acne. Participants applied a gel daily for eight weeks containing glycolic acid, niacinamide, salicylic acid, an antimicrobial peptide and two forms of retinoids. The results show a marked reduction in acne, without any increase in transepidermal water loss, a problem frequently encountered with glycolic acid-based blemish-control formulations.

Another positive point: the product was very well tolerated and no cases of erythema or dryness were reported. That said, it is important to note that the tested formulation contained several active ingredients in addition to glycolic acid and niacinamide. Therefore, it is difficult to attribute all observed effects solely to this combination. Nonetheless, these two actives most likely contribute significantly to the product’s efficacy against acne lesions and its good tolerability.

The glycolic acid/niacinamide combination is not only useful for treating blemishes: it could also be relevant for reducing the signs of photoaging. In any case, this is what a study suggests, one that examined the efficacy of a gel-cream combining three active ingredients (retinaldehyde, glycolic acid and niacinamide) in 40 women with moderate to severe facial photodamage. Participants applied the product every evening for 60 days. Clinical and instrumental evaluations were conducted before application, at 30 days, and at 60 days, and biopsies were used to measure changes in collagen fiber density in the periocular area.

The results demonstrated an overall improvement in skin appearance, with smoothing of wrinkles and fine lines, increased skin firmness, enhanced texture and hydration, as well as a reduction in brown spots. Ultrasonography revealed a significant increase in dermal density across all participants, and histological analysis showed an average increase of 47.8% in the number of collagen fibers compared to baseline. These data suggest that glycolic acid and niacinamide, when combined with retinaldehyde, may help attenuate the signs of skin aging.

Finally, combining glycolic acid and niacinamide could be interesting for individuals with hyperpigmentation. Indeed, these actives each work to reduce brown spots: glycolic acid by exfoliating melanin-laden dead cells, and niacinamide by inhibiting melanosome transfer to keratinocytes. Therefore, combining them appears relevant for reducing hyperpigmentation, as demonstrated by research led by Fabbrocini and colleagues. In that study, eleven subjects with hyperpigmentation applied a serum containing niacinamide, glycolic acid, hydroxyphenoxypropionic acid, dipotassium glycyrrhizate, and 4-n-butylresorcinol twice daily, alongside a sunscreen. The results showed a significant decrease in the MASI score, which evaluates the severity of hyperpigmentation.

The improvement in skin tone uniformity is also visually impressive, as shown in the participant’s photos below.

However, caution is still warranted. While the tested formulation appeared effective, it did not contain only glycolic acid and niacinamide. Furthermore, no control was employed. One may thus question whether the favorable outcomes arise from the niacinamide, the glycolic acid, their combination, or the serum’s other active compounds. Consequently, even though pairing glycolic acid with niacinamide seems promising for reducing brown spots, additional studies are necessary to confirm any synergistic effect.

• PARK U. S. & al. Clinical, histologic, and instrumental assessment of a gel cream containing retinaldehyde, glycolic acid, and niacinamide in females with moderate to severe facial photoaging. Journal of the American Academy of Dermatology (2012).

• SHARAD J. Glycolic acid peel therapy – A current review. Clinical, Cosmetic and Investigational Dermatology (2013).

• KREFT D. & al. Niacinamide - Mechanisms of action and its topical use in dermatology. Skin Pharmacology and Physiology (2014).

• FABBROCINI G. & al. Efficacy and safety of a new topical gel formulation containing retinol encapsulated in glycospheres and hydroxypinacolone retinoate, an antimicrobial peptide, salicylic acid, glycolic acid and niacinamide for the treatment of mild acne: Preliminary results of a 2-month prospective study. Giornale Italiano di Dermatologia e Venereologia (2020).

• FABBROCINI G. & al. An open-label, investigator-initiated, single-center, prospective, pilot clinical study to evaluate the efficacy of a skin whitening serum applied twice daily combined with a spot-preventing SPF50+ sunscreen in healthy female subjects with melasma hyperpigmentation. Journal of Cosmetic Dermatology (2021).