Mandelic Acid and Hair: What are the Benefits?

Derived from bitter almond, themandelic acid is an aromatic alpha-hydroxy acid (AHA), primarily used in skincare to enhance the texture and appearance of the skin, as well as to treat acne, hyperpigmentation and the effects of aging, notably due to its keratolytic, keratoplastic, and antimicrobial properties. To reap its benefits, one should opt for skincare products containing at least 5 to 10% mandelic acid. In excess, it can lead to side effects.

Unlike other fruit acids, mandelic acid is generally safe and well-tolerated by all skin types. Its large molecular size allows it to penetrate the epidermis slowly, making it a better alternative to glycolic or lactic acid for sensitive skin. However, in some cases, it can cause side effects, such as dry skin, a warm sensation, tingling, redness, and itching.

Shampoo, scalp exfoliation... mandelic acid can also be incorporated into hair care formulations. Its gentle exfoliating power can help remove the buildup of scales adhering to the scalp, as well as excess sebum and all other underlying impurities, thereby freeing the pores. This encourages cell renewal, or the emergence of new cells, and sanitizes the scalp, while reducing inflammation.

A recent study examined the use of a shampoo containing ichthyol (1.2%), mandelic acid (1.2%), zanthalene (< 1%), and honeydew honey (< 1%) in the treatment of mild to moderate scalp psoriasis. Thirty subjects with mild to moderate psoriasis, aged 18 to 65, were instructed to apply the shampoo three times a week for 12 weeks. They were also instructed not to use any other shampoo or topical medication on the scalp, as it could potentially interfere with the treatment's effectiveness.

Shampoo Composition : Ichthyol has anti-microbial and anti-inflammatory activity. Themandelic acid has exfoliating effects and stimulates cellular renewal, well-known properties that help to eliminate dandruff. Zanthalene is an ingredient extracted from Sichuan pepper, a Chinese spice used to soothe discomforts by acting on neuromuscular communication within the skin's structure. Honeydew honey has moisturizing, softening, and soothing virtues; it helps to maintain a soft and protected scalp, and alleviates irritations.

As a reminder, psoriasis is a recurring chronic inflammatory skin disease characterized by an abnormal hyperproliferation of keratinocytes, leading to a thickening of the stratum corneum, vasodilation, increased permeability, and inflammation. Scalp involvement is a common clinical aspect of psoriasis. It is characterized by erythema (redness) and desquamation (scaling), sometimes associated with a sensation of itching. Despite a wide range of therapeutic options, scalp psoriasis remains difficult to treat.

The results obtained show a significant reduction in the severity of scalp psoriasis. Indeed, the use of the shampoo significantly decreased erythema in 87.50% of patients and scaling in 89.05% of patients. Furthermore, no side effects were observed or reported. The researchers conclude by indicating that this shampoo could constitute an effective adjunct treatment to modulate scaling, itching, and inflammation, the characteristics of scalp psoriasis.

• CAMELI N. & al. Clinical and videodermoscopic assessment of the effectiveness, safety, and tolerability of a shampoo containing ichthyol, zanthalene, mandelic acid, and honey in the treatment of scalp psoriasis. Skin Appendage Disorders (2018).