Glycolic acid and dandruff: what are the effects?

Dandruff is a common condition that can be attributed to a variety of underlying factors, including seborrhoeic dermatitis, fungal overgrowth (Malassezia), dry skin, excessive sebum production, skin conditions such as psoriasis and eczema, sensitivity to haircare products, and inadequate scalp hygiene.

Dandruff is the hyperproliferation of the scalp epidermis, characterised by an accumulation of scales, an oily, red and flaky scalp, often accompanied by itching. At varying levels of severity it affects nearly 50% of the adult population, and factors such as hormonal influence, climatic changes, physical trauma and stress can exacerbate the underlying causes of dandruff.

Mild dandruff, characterised by symptoms such as flaking, itching and moderate erythema, can be difficult to diagnose accurately on appearance alone, often necessitating more comprehensive analysis to determine the precise aetiology. Nevertheless, certain skincare formulations demonstrate potential in addressing some of the symptoms, including glycolic acid. Renowned for its keratolytic and hydrating properties, glycolic acid may help mitigate several of these common scalp issues.

A study conducted by PIRACCINI et al. (2018) assessed the efficacy of a shampoo containing glycolic acid, together with urea, salicylic acid, pale ichthyol and laureth-9, in managing scalp conditions such as dandruff. The investigation showed that this medicated shampoo significantly outperformed a standard shampoo in reducing yellow and white scales, alleviating local erythema and lowering sebum levels on the scalp. The product was also well tolerated by participants, with minimal adverse effects reported. Specifically:

• Reduction of Flakes: The shampoo reduced yellow scales in 87.5 per cent of cases and white scales in 100 per cent of cases, compared with the low efficacy of the non-specific shampoo.

• Sebum reduction: The shampoo reduced sebum production on the scalp in 70% of participants, compared with only 10% of those using the generic shampoo.

• Moisturisation and Hair Strength: According to this study, glycolic acid contributed to maintaining hair moisturisation, strengthening the hair and preventing breakage, especially during heat styling. However, since salicylic acid was also present, the benefits could be attributed to it or the combination of both acids, making it difficult to isolate glycolic acid’s specific effects, thereby limiting the insights gained from the study.

These findings suggest that glycolic acid, when utilised in combination with other active ingredients, can effectively improve scalp health and reduce the symptoms of dandruff.

How does glycolic acid remove dandruff?

Glycolic acid’s main benefits stem from its keratolytic and moisturising properties:

• Exfoliation: Glycolic acid, the smallest of the alpha hydroxy acids (AHAs), efficiently penetrates the stratum corneum owing to its small molecular size. This deep penetration enables it to break the bonds between dead skin cells, facilitating the removal of flaky build-up on the scalp. The result is a reduction in visible dandruff and an improvement in scalp texture through enhanced cellular turnover.

• Moisture Retention: Glycolic acid’s high water solubility improves its capacity to attract and retain moisture on the scalp. This characteristic is essential for preventing the excessive dryness that can cause dandruff, supporting a hydrated and balanced scalp environment by enhancing the skin’s moisture barrier.

• Sebum Regulation: Although direct research into the effects of glycolic acid specifically on dandruff is limited, studies on skin and acne have demonstrated its ability to regulate sebum production. This regulation is likely attributable to its exfoliating action, which helps clear pores and normalise skin turnover, suggesting a potential benefit in managing scalp oiliness and thus reducing a key contributor to dandruff formation.

Glycolic acid is commonly incorporated in commercial shampoos alongside other ingredients such as zinc pyrithione (an antifungal agent) and salicylic acid, which help address various aspects of dandruff. Although its efficacy as a standalone treatment for dandruff has not been extensively studied, its use in dermatology and its capacity to exfoliate dead skin cells and regulate sebum production suggests potential benefits, particularly for mild to moderate dandruff. However, more severe cases may necessitate more potent therapies such as corticosteroids.

Studies, such as those by Kostarelos et al. (2000), have demonstrated its efficacy in treating conditions such as scalp psoriasis, which presents with symptoms similar to those of dandruff-related disorders. This provides an encouraging foundation for the use of glycolic acid in managing dandruff, although conclusive evidence and further research are necessary to confirm its stand-alone efficacy and optimal integration into treatment regimens for severe scalp conditions.

• MINAS A. & al. Double-blind clinical study reveals synergistic action between alpha-hydroxy acid and betamethasone lotions towards topical treatment of scalp psoriasis. Journal of the European Academy of Dermatology and Venereology (2000).

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

• CHANDAK A. & al. Antimicrobial activity of natural herbal products against dandruff causing fungus and bacteria. World Journal of Pharmaceutical Research (2018).

• STARACE M. & al. Efficacious and safe management of thick scales, redness and flaky scalp condition using a specific shampoo containing urea, glycolic acid, salicylic acid, icthyol pale and laureth 9. Cogent Medicine (2018).

• MUKOVOZOV I. & al. Topical AHA in dermatology: Formulations, mechanisms of action, efficacy, and future perspectives. Cosmetics (2023).