(Patel 2021) (Misery 2023)
The evaluation of sensitive skin is useful for assessing the effectiveness of certain products. The “International Forum for the Study of Itch (IFSI) defined sensitive skin as follows: “A syndrome defined by the occurrence of unpleasant sensations (stinging, burning, pain, pruritus, and tingling sensations) in response to stimuli that normally should not provoke such sensations. These unpleasant sensations cannot be explained by lesions attributable to any skin disease. The skin can appear normal or be accompanied by erythema. Sensitive skin can affect all body locations, especially the face.
In a meta-analysis, cosmetics and physical (variations in temperature, cold, heat, wind, sun, air, conditioning, wet hair and dry hair), chemical (water and pollution) or psychological (emotional) factors are associated with sensitive skin. The most important factors are cosmetics, air conditioning, heat, and water).
The global prevalence of “Sensitive Skin” is approximately 50% with variations among some countries.
According to the high frequency of sensitive skin, a single pathophysiological mechanism is debatable. However, a growing body of data supports the hypothesis that sensitive skin is a neuropathic disorder.
The famous lactic acid stinging test (LAST) of Frosch and Kligman is the first standardized test. It consists of the application of 0.5 mL of 10% (or 5%) lactic acid to the nasolabial fold with subsequent assessment of the severity of the subjective symptoms. Erythema is evaluated. Control is provided by the application of a saline solution to the other fold. This test is very commonly used and is very useful for follow-up. (Maheshvari N Patel n.d.)
A 0.075% emulsion of capsaicin is applied. Similar to the LAST, it could have been controversial since involving the use of a subjective individual pain scale as well and it induced too painful sensations in very sensitive skin subjects.
The aim of other tests is to evaluate skin properties which can be modified in subjects with sensitive skin but are not directly related to sensitive skin. Hence, the measurement of structural or physiological cutaneous changes after the application of topical irritants can be performed: Trans Epidermal Water Loss (TWEL), cutaneous pH, and epidermal thickness, measured by ultrasonography, optical microscopy, or confocal microscopy, as well as skin penetrability, assessed with UV light, can be studied parameters. Recently, the use of confocal Raman microspectroscopy was proposed to analyze the molecular composition of stratum corneum and consequently the modifications of the skin barrier in sensitive skin. All these tests are commonly used in studies on sensitive skin, but they do not measure skin hypersensitivity.
*Sensitive scale (SS-10) is a 10-item scale. Correlation with the dry skin type, higher age, female gender, fair phototypes, and the Dermatology Quality of Life Index (DLQI). DLQI is a tool to evaluate the quality of life in patients with skin disorders.
*Important to be completed by the Patient.
Using a vertical line, indicate the symptoms felt during the past 3 days on the horizontal line (0=absence of irritation, 10 = intolerable irritation)
Skin Condition Felt
Visible skin condition
The total score can be obtained by multiplying score severity of abnormal sensations by the number of these sensations. The 3S questionnaire allowed discrimination between subjects with slightly sensitive, sensitive and very sensitive scalp. Itching and prickling are the most frequent symptoms. The 3S questionnaire is a convenient and effective tool for investigating the severity and symptomatology of the sensitive scalp.
|For each of the 5 following symptoms (do you feel itching, prickling, tightness, pain or burning on your scalp?), which of the statements below best describes how it affects you.|
|No, I do not feel it|
|Yes, but it is not troublesome|
|Yes, and it is slightly troublesome|
|Yes, and it is sufficiently troublesome to alter my lifestyle|
|Yes, and it is unbearable|
The BoSS questionnaire is designed to evaluate all these aspects in patients with sensitive skin. This questionnaire was developed using standardized methods for creating and validating quality-of-life questionnaires, consisting of three phases: a design phase, a development phase, and a validation phase.
A large number of techniques for sensitive skin testing suggests that the authors may try to find a technique for the diagnosis of sensitive skin. In any case, all these subjective and objective tools for sensitive skin testing can be used in comparative studies, especially those that evaluate the efficacy and/or safety of cosmetics and cosmeceuticals.