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

The glycolic acid and the niacinamide are among the most studied and widely used actives in cosmetics, each acting via distinct but complementary biological mechanisms. The glycolic acid primarily reduces corneocyte cohesion in the stratum corneum, accelerating desquamation to improve skin tone uniformity and refine skin texture. The niacinamide has, for its part, a broader action profile. It strengthens the barrier function of the skin by increasing ceramide synthesis, which enhances 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 perfectly feasible to combine glycolic acid and niacinamide in the same cosmetic formulation. However, it is inadvisable to layer two separate products, as glycolic acid requires an acidic pH (≈ 3–4) to perform its exfoliating action, whereas niacinamide serums are formulated at a more neutral pH (≈ 5–7).

Several recent studies emphasise that the combination of glycolic acid and niacinamide may be beneficial in reducing imperfections while strengthening the skin barrier. A study conducted with 25 participants evaluated a formulation combining several actives, 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 demonstrate a marked reduction in acne, without any increase in water loss, a problem frequently encountered with blemish-targeting formulations based on glycolic acid.

Another positive aspect: the product was very well tolerated and no cases of erythema or dryness were reported. However, it is important to note that the formulation under investigation contained several actives in addition to glycolic acid and niacinamide. Thus, it is difficult to attribute all the observed effects solely to this combination. Nonetheless, these two actives very likely contribute to the product’s efficacy on acne lesions and to its good tolerability.

The glycolic acid/niacinamide combination is not only of interest in cases of blemishes: it could also be relevant to mitigating the signs of photoageing. This, at least, is what a study suggests, having 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. The participants applied the product every evening for 60 days. Clinical and instrumental assessments were conducted before application, at 30 days and at 60 days, and biopsies were used to measure changes in collagen fibre density in the periocular region.

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

Finally, combining glycolic acid and niacinamide could be interesting for individuals with hyperpigmentation. In fact, these actives each work to reduce brown spots—glycolic acid by removing dead cells laden with melanin, and niacinamide by limiting the transfer of melanosomes to keratinocytes. It therefore seems appropriate to pair them to tackle hyperpigmentation, as demonstrated by research led by Fabbrocini and colleagues. In that study, eleven participants with hyperpigmentation applied a serum twice daily containing niacinamide, glycolic acid, hydroxyphenoxypropionic acid, dipotassium glycyrrhizate and 4-n-butylresorcinol, alongside a sunscreen. The results showed a significant decrease in the MASI score, which assesses the severity of hyperpigmentation.

The improvement in skin tone uniformity is also visually striking, as shown by the photographs of a participant below.

However, caution remains advisable. The tested formulation appears to have been effective, but it did not comprise solely glycolic acid and niacinamide. Furthermore, no control was incorporated. It is therefore reasonable to question whether the positive outcomes arise from the action of niacinamide, glycolic acid, their combination, or indeed from other active constituents of the serum. Thus, even though the pairing of glycolic acid and niacinamide seems relevant for combating brown spots, further studies are still necessary to substantiate their synergy.

• 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).