BODY CARE
Investigative methods dedicated to axilla skin
Fabrice Perin, Suparat Kasamtammakhun, Chanasak Pothi, Surachet Saelu, Kunyanatt Chalothorn - DermaProof Asia
The skin of the axilla (underarm or armpit area) has several distinctive characteristics that differentiate it from other body sites. These specificities are important to consider in the context of skin care, deodorants, antiperspirants, and overall hygiene. Compared to other parts of the body, some
of the key features of axillary skin are thinner epidermis and dermis (which makes it more sensitive and susceptible to irritation), its high density of sweat glands (eccrine, apocrine and apoeccrine, which are hybrid glands developing during puberty). The axilla is a hair-bearing area in both men and women where skin is often folded.
The combination of skin folds, nutrient-rich
sweat gland secretions and hairs creates a very favourable environment for bacterial growth leading to a distinct microbiome that includes a higher concentration of bacteria, especially Corynebacterium and Staphylococcus species. Organic molecules present in odourless
perspiration, especially apocrine perspiration, get metabolized by these bacteria. As an undesirable consequence, the axillary malodour is caused by a combination of volatile fatty acids, aldehydes, thioalcohols and steroids, which are byproducts from the bacterial metabolization of proteins and lipids present in human sweat. Removing axillary hairs, thus addressing the
issue of body odour, is important to improve self-esteem and decrease the negative effect upon social relationships.1
Yet the use of
shaving, waxing or other hair removal methods can contribute to irritation. The folded texture of the axilla region that
tends to retain more moisture and makes the skin prone to maceration, the use of deodorants and antiperspirants are factors further contributing to irritation, redness and itching. The same factors together with the friction inherent to this body area are responsible of the appearance of cutaneous hyperpigmentation. The last concern for many individuals is
the so-called ‘chicken skin’, a pictorial term describing the small, raised bumps that can appear on the skin of the armpits. The physiological specificities of the
axillary skin presented above implies the use of particular skin care, hygiene and aesthetic treatments. Removing axillary hair has become routine for women and men as well and helps mitigate armpit malodour.1 Antiperspirants and deodorants are used to reduce excessive sweating and mask odours.
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Products designed specifically for the sensitive axillary skin can also prevent or mitigate the risk of irritation or improve other conditions like hyperpigmentation and texture. In this short review article, we intend
to briefly present the rationale behind the rigorous evaluation of the cosmetic or aesthetic treatments for the axilla, focusing on in vivo test methods, which are the most suitable options in the perspective of gathering evidences to support claims. It is fair to assume that in vitro methods are primarily interesting for validating the proofs of concept of new active ingredients and interventions.
In vivo assessment of antiperspirants While mandatory efficacy testing is not universally required by law in all markets, it is often essential for regulatory approval, particularly in the USA and Canada where antiperspirants are regulated as over-the- counter drugs and drug products respectively, and can be crucial for making claims about
effectiveness in Europe and in many other countries. Furthermore, companies may voluntarily
conduct such testing to improve product credibility and align with industry standards. Although guidelines aiming at standardizing testing do not exist for many cosmetic claims, there are some for antiperspirants and deodorants.2
In the United States, the Food
and Drug Administration has an antiperspirant monograph that provides the regulatory framework for the safety and efficacy testing, and labeling claims. Demonstrating the effectiveness of an
antiperspirant means evaluating its ability to reduce sweating. The most common way to assess this effect is through gravimetric methods. The test consists in submitting the participants to controlled exercise or heat exposure to induce sweating. Pre-weighed filters or pads are used to
collect sweat from the underarms. The amount of sweat output is measured before and after
April 2025 PERSONAL CARE
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