Glycolic acid and dandruff: what are the effects?

Dandruff is a common condition that can be caused by a variety of underlying factors, including seborrheic dermatitis, fungal overgrowth (Malassezia), dry skin, excessive oil production, skin conditions like psoriasis and eczema, product sensitivities, and improper scalp hygiene. 

Dandruff is the hyperproliferation of the scalp epidermis, characterized by accumulation of scales, oily, red and flaky scalp, often accompanied by itching. In different severity levels, it affects nearly 50% of the adult population and factors such as hormonal influence, climate changes, physical trauma, and stress can worsen the underlying causes of dandruff. 

Mild dandruff, characterized by symptoms like flaking, itching, and moderate redness, can be challenging to diagnose accurately just by its appearance, often necessitating more in-depth analysis to pinpoint the exact cause. Despite this, certain skincare products show potential for addressing some of the symptoms, including glycolic acid. Known for its exfoliating and moisturizing benefits, glycolic acid could potentially help alleviate some of these common scalp issues.

A study conducted by PIRACCINI & al. (2018) examined the effectiveness of a shampoo containing glycolic acid, along with urea, salicylic acid, icthyol pale, and laureth-9, in managing scalp issues like dandruff. The study found that this medicated shampoo significantly outperformed a generic shampoo in reducing yellow and white scales, reducing local redness (erythema), and decreasing scalp sebum levels. The shampoo was also well tolerated by participants, with minimal adverse effects reported. Specifically:

• Reduction of Flakes: The shampoo reduced yellow scales in 87.5% of cases, and white scales in 100% of cases, compared to the low effectiveness of the nonspecific shampoo.

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

• Moisturization and Hair Strength: According to this study, glycolic acid contributed to maintaining hair moisture, 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, thus limiting the insights from the study.

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

How does glycolic acid eliminate dandruff?

Glycolic acid's main benefits stem from its keratolytic and moisturizing properties:

• Exfoliation: Glycolic acid, the smallest of the alpha hydroxy acids (AHAs), efficiently penetrates the stratum corneum due to its small molecular size. This deep penetration allows it to break the bonds between dead skin cells, facilitating the removal of flaky buildup 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 enhances its ability to attract and retain moisture on the scalp. This property is crucial for preventing the excessive dryness that can lead to dandruff, helping to maintain a hydrated and balanced scalp environment by improving the skin’s moisture barrier.

• Sebum Regulation: Although direct research on glycolic acid’s effects specifically on dandruff is scarce, studies on skin and acne have shown its capability to regulate sebum production. This regulation is likely due to its exfoliating action which helps clear pores and normalize skin turnover, suggesting a potential benefit for managing scalp oiliness and thus reducing a key contributor to dandruff formation.

Glycolic acid is commonly included in commercial shampoos with other ingredients like zinc pyrithione (an antifungal agent) and salicylic acid, which help manage different aspects of dandruff. While its standalone efficacy in dandruff treatment hasn't been extensively studied, its use in dermatology and its ability to exfoliate dead skin cells and regulate sebum suggests potential benefits, particularly for mild to moderate dandruff. However, more severe cases may require stronger treatments like corticosteroids. 

Studies, such as those by KOSTARELOS & al. (2000), have shown its effectiveness in treating conditions like scalp psoriasis, which shares symptoms with dandruff-related disorders. This gives an encouraging basis for glycolic acid in dandruff management, although conclusive evidence and further research are needed to confirm its standalone 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).