Abstract
Objective
Sensitive skin syndrome (SSS) affects individuals from all ethnic groups. However, studies across different populations remain limited, despite recognised differences between populations. Thus, we examined SSS in Thai and Polish subjects, assessing the tolerance and efficacy of a dermo‐cosmetic product in both populations.
Methods
Thai participants were involved in a 28‐day open‐label study, while Polish subjects took part in a 56‐day double‐blind, randomised study comparing the product with a control cream. Clinical and functional signs were evaluated, alongside quality of life (QoL) using the Burden of Sensitive Skin (BoSS) questionnaire.
Results
The product was well tolerated in both groups over time, leading to significant improvements in all clinical and functional signs (p < 0.05 to p < 0.001) and enhancing QoL (p < 0.005 in Thailand; p < 0.001 in Poland). At baseline, Polish subjects exhibited greater redness and higher BoSS scores to questions relating to visual signs (p < 0.001). Conversely, Thai participants reported more pronounced tingling, pain and itching, along with higher BoSS scores relating to sensory symptoms (p < 0.001).
Conclusions
The study highlights differences existing in the perception of SSS symptoms between a Thai and Polish population and demonstrates that the dermo‐cosmetic cream effectively alleviates SSS symptoms and improves QoL in both ethnic groups.
Keywords: Asian, burden, Caucasian, dermo‐cosmetic, sensation, sensitive skin
Sensitive skin assessment in Thai and Polish subjects showed a dermo‐cosmetic product improved symptoms and quality of life in both groups, also highlighting ethnic differences in syndrome perception at baseline.
Résumé
Objectif
Le syndrome de la peau sensible touche des individus de tous les groupes ethniques. Toutefois, les études menées sur différentes populations restent limitées, malgré les différences reconnues entre ces dernières. Ainsi, nous avons examiné le syndrome de la peau sensible chez des sujets thaïlandais et polonais, en évaluant la tolérance et l'efficacité d'un produit dermo‐cosmétique dans les deux populations.
Méthodes
Les participants thaïlandais ont pris part à une étude ouverte de 28 jours, tandis que les sujets polonais ont participé à une étude en double aveugle, randomisée, de 56 jours, comparant le produit à une crème neutre. Les signes cliniques et fonctionnels ont été évalués, ainsi que la qualité de vie à l'aide du questionnaire BoSS (Burden of Sensitive Skin pour fardeau de la peau sensible).
Résultats
Le produit a été bien toléré dans les deux groupes, entraînant une amélioration significative de l'ensemble des signes cliniques et fonctionnels (p < 0.05 à p < 0.001), ainsi qu'une amélioration de la qualité de vie (p < 0.005 en Thaïlande; p < 0.001 en Pologne). Au début de l'étude, les sujets polonais présentaient une rougeur plus marquée et des scores BoSS plus élevés concernant les signes visuels (p < 0.001). En revanche, les participants thaïlandais rapportaient des sensations de picotement, de douleur et de démangeaison plus intenses, ainsi que des scores BoSS plus élevés en lien avec les symptômes sensoriels (p < 0.001).
Conclusions
L'étude a permis de mettre en évidence des différences dans la perception des symptômes de la peau sensible entre les populations thaïlandaise et polonaise, et de démontrer que la crème dermo‐cosmétique soulage efficacement les symptômes de la peau sensible et améliore la qualité de vie dans les deux groupes ethniques.
INTRODUCTION
In 2016, the International Forum for the Study of Itch defined sensitive skin syndrome (SSS) as a condition characterized by unpleasant sensations such as stinging, burning, pain, itching and tingling in response to stimuli that should not provoke such reactions [1]. Although the skin may appear normal or exhibit redness, SSS is not necessarily associated with objective clinical signs, albeit with obvious alterations of the skin barrier function and modifications of the stratum corneum [2, 3]. Symptoms typically manifest immediately after exposure to triggers, which can be physical, chemical or, in some cases, emotional [4]. The duration of these reactions varies, ranging from a few minutes to several hours [1, 5]. Both the physical discomfort and the emotional impact of SSS can significantly affect patients' quality of life. The pathophysiology of SSS remains the subject of intensive research, with proposed hypotheses focusing particularly on neurosensory system dysfunction and disruption of the epidermal barrier function [6, 7].
Epidemiological studies have reported varying prevalence rates of SSS, though it is estimated that up to 70% of individuals may be affected, with this number seemingly rising in recent years [8]. SSS has been reported worldwide, yet studies across different populations have yielded conflicting results [9, 10, 11, 12]. The earliest such study reported a similar prevalence among African Americans, Asians, European Americans and Hispanics, though some differences were noted in the factors triggering symptoms [9]. However, as the authors acknowledged, this study could not fully explore the extent of SSS triggers, especially environmental factors, since all subjects resided in the same geographical area. Among subsequent works, some have shown that sensitive skin tends to be more common in lighter skin types than in individuals with darker skin [13, 14]. Differences in skin structure and function across ethnic groups may contribute to these differences [7, 15].
Further studies on the clinical and functional signs of SSS across ethnic groups remain necessary to gain an understanding on a global scale. Additionally, research assessing the effectiveness of cosmetic products as part of SSS management should consider diverse populations. Accordingly, by comparatively evaluating the effects of a dermo‐cosmetic product on Polish and Thai subjects suffering from SSS, one of our objectives was to explore potential differences in the objective and subjective assessment of symptoms in these two groups while seeking to understand the impact of SSS on their quality of life using the Burden of Sensitive Skin (BoSS) questionnaire [16].
MATERIALS AND METHODS
Investigational product
The investigational product is the Sensibio Defensive Rich Cream, a commercially available dermo‐cosmetic facial cream manufactured by Bioderma (NAOS Ecobiology Company, France). This unscented oil‐in‐water emulsion is formulated with active ingredients aimed at alleviating skin sensitivity by addressing the underlying causes of SSS and preventing sensitivity induced by daily aggressors.
The detailed INCI composition of the investigational product is as follows: aqua (water), glycerin, glycerin, dicaprylyl ether, glycol palmitate, butylene glycol, cetyl palmitate, glyceryl stearate citrate, squalane, sucrose stearate, tridecyl trimellitate, glyceryl dibehenate, polysorbate 60, pentylene glycol, tribehenin, glyceryl behenate, acrylates/c10‐30 alkyl acrylate crosspolymer, caprylyl glycol, carnosine, hydroxyethyl acrylate/sodium acryloyldimethyl taurate copolymer, mannitol, xylitol, tocopherol, salvia miltiorrhiza flower/leaf/root extract, rhamnose, glycine soja (soybean) oil, sorbitan isostearate, sodium hydroxide and palmitoyl tetrapeptide‐10 [BI 2003].
For the study conducted in Poland, a control cream with a basic formulation was used. Its INCI composition included aqua (water), caprylic/capric triglycerides, glyceryl stearate citrate, sucrose stearate, xanthan gum, pentylene glycol, sodium polyacrylate, 1,2‐hexanediol, caprylyl glycol, citric acid and glycerin.
Study design
The investigational cream was evaluated in two studies, one conducted in Thailand (Bangkok) and the other in Poland (Warsaw). Upon enrolment, all subjects self‐reported having sensitive skin and presented BoSS scores of 20 or higher [16].
The Thai study was an open‐label, monocentric, dermatologist‐controlled clinical evaluation conducted over 28 days, between mid‐September 2022 and mid‐January 2023. Forty subjects applied the investigational product twice daily (morning and evening) while maintaining their usual skincare routine (cleansing product(s), sunscreen and makeup if applicable).
The Polish study was a double‐blind, randomized, controlled, comparative, monocentric, dermatologist‐controlled clinical evaluation conducted over 56 days, between mid‐May 2022 and mid‐January 2023. Most inclusions (72%) occurred in September. Participants were randomly assigned to either the investigational product group (n = 50) or the control cream group (n = 50). Both products were applied twice daily (morning and evening), with subjects continuing their regular facial skincare regimen.
In addition to the general inclusion criteria, Polish subjects also had to show a positive reaction (global score ≥3) in the Lactic Acid Stinging Test (LAST) and exhibit LAST‐induced facial redness, as measured by a Mexameter® (Courage + Khazaka electronic GmbH, Germany).
All assessments/measurements were conducted in a controlled environment (20 ± 2°C and 50 ± 5% relative humidity) after 15 min of acclimation.
Ethics
The clinical study conducted in Thailand was approved by the Institutional Review Board under the reference Si502/2022. In Poland, approval was granted by the Bioethics Committee of the Regional Medical Chamber in Warsaw under the reference KB/1385/22. Both studies adhered to the principles outlined in the Declaration of Helsinki and complied with Good Clinical Practices. Participants received comprehensive information regarding the study's purposes, procedures, potential risks and objectives. All gave their written informed consent prior to enrolment.
Clinical and functional assessments
In both the Polish and Thai studies, clinical signs (redness, dryness, roughness and scaling) were assessed on an 11‐point scale (0 = none to 10 = severe) by both dermatologists and subjects on days 0 (D0), 28 (D28) and 56 (D56). Functional signs (itching, pain, tightness, tingling and heat sensations) were self‐rated by subjects using the same numerical 11‐point scale.
BoSS questionnaire
The BoSS questionnaire, devised by Misery et al. [16], enables subjects to self‐assess the burden of their sensitive skin. It was administered to all subjects on D0, D28 and D56 (Polish study only).
The questionnaire consists of 14 items grouped into three categories:
Self‐care (finding wool uncomfortable, impact on the purchase of clothing, on the choice of laundry detergent, soap, clothes in the morning, cosmetics and jewellery).
Daily life (food restrictions, impact on the choice of leisure activities or relating to air conditioning and pollution).
Appearance (blushing with emotion, after physical activity and annoyance when photographed).
Each item is rated on a five‐point scale (0 = never to 4 = constantly). The global score, ranging from 0 to 56, is obtained by summing the scores from all 14 questions.
Corneometry and TEWL measurements
In the Thai study, changes in skin hydration over the study period were quantified by measuring the skin's electrical capacitance using the Corneometer® CM825 (Courage + Khazaka electronic GmbH, Germany). Skin barrier function was evaluated by measuring transepidermal water loss (TEWL) with the Tewameter® TM300 (Courage + Khazaka electronic GmbH, Germany). Both measurements were conducted on the subjects' malar area (pre‐defined facial site #18 as referenced by Voegeli et al. [17]) at baseline (D0) and D28.
Lactic acid stinging test
In the Polish study, all subjects underwent a lactic acid stinging test (LAST) on D0, D28 and D56 to assess cutaneous reactivity [17].
Following cleansing of the nasolabial folds with a 10% hydroalcoholic solution, a randomly selected nasolabial fold received topical application of a 10% lactic acid solution, while a 0.9% saline solution was applied to the second nasolabial fold. Subjects rated their stinging sensation on both sides using a four‐point scale (0 = none to 3 = severe) 150 s after application. The LAST score was calculated as the difference between the score of the lactic acid‐treated side and that of the physiological serum‐treated side.
Tolerance assessment
In both the Polish and Thai studies, subjects were required to report any adverse effects (appearance of redness, oedema, vesicles, papules, desquamation, itching, sensations of tingling, heat, burning or tightness) occurring during or shortly after product application. These signs were evaluated by dermatologists using a four‐point scale (very good, good, moderate or poor tolerance).
Statistical analysis
Results are reported as mean ± standard deviation (SD). Data distribution was assessed using the Shapiro–Wilk test (α < 0.01). TEWL and electrical capacitance, which followed a normal distribution, were compared using paired or unpaired Student's t‐tests. For all other parameters, the Wilcoxon signed‐rank test was employed to compare paired datasets, while unpaired datasets were analysed using the Mann–Whitney test. Statistical significance was set at p < 0.05 (*p < 0.05, **p < 0.01, ***p < 0.001).
RESULTS
Subject characteristics
The characteristics of the subjects in the Polish and Thai studies are detailed in Table 1.
TABLE 1.
Characteristics of the three groups studied.
| Product Thailand (n = 40) | Product Poland (n = 50) | Control Poland (n = 50) | |
|---|---|---|---|
| Mean age (min–max) | 43.1 (20–62) | 41.7 (20–64) | 44.4 (22–63) |
| Gender | |||
| Female | 87.5% | 80% | 80% |
| Male | 12.5% | 20% | 20% |
| Skin type | |||
| Oily | 17.5% | 0% | 0% |
| Mixed | 52.5% | 48% | 36% |
| Normal | 2.5% | 2% | 12% |
| Dry | 27.5% | 50% | 52% |
| Phototype | |||
| II | 0% | 56% | 52% |
| III | 15% | 44% | 48% |
| IV | 55% | 0% | 0% |
| V | 30% | 0% | 0% |
| Smoker | |||
| Yes | 2.5% | 16% | 16% |
| No | 97.5% | 84% | 84% |
| Mean BoSS score at D0 | 34.12 | 29.06 | 29.78 |
Abbreviations: BoSS, Burden of Sensitive Skin Syndrome; max, maximum; min, minimum.
Thai study
According to dermatologists (Figure 1) and subjects (Figure 2), after 28 days of twice‐daily product application, there was a significant reduction in redness (−36%, p < 0.05; −68%, p < 0.001, respectively), dryness (−59% and −72%, respectively; p < 0.001 for both), roughness (−44% and −74%, respectively; p < 0.001 for both) and scaling (−51%, p < 0.05; −77%, respectively, p < 0.001) compared to baseline (D0).
FIGURE 1.
Average clinical scores given by dermatologists for (a) redness, (b) dryness, (c) roughness and (d) scaling in the three groups of subjects. Only significant p‐values are reported with: * intra‐treatment significance versus baseline, ° significance between the product and the control in the Polish study (identical timepoint) and • significance between the Thai and Polish group at baseline. *: p < 0.05, **, °°, ••: p < 0.01 and ***, °°°, •••: p < 0.001.
FIGURE 2.
Average clinical scores rated by subjects for (a) redness, (b) dryness, (c) roughness and (d) scaling in the three groups of subjects. Only significant p‐values are reported with: * intra‐treatment significance versus baseline, ° significance between the product and the control in the Polish study (identical timepoint) and • significance between the Thai and Polish group at baseline. ***, °°°, •••: p < 0.001.
After 28 days of use, all functional signs rated by subjects were significantly reduced: tightness (−75%), tingling (−73%), pain (−83%), heat sensations (−81%) and itching (−80%; p < 0.001 for all; Figure 3).
FIGURE 3.
Average scores for functional signs rated by subjects for (a) tightness, (b) tingling, (c) pain, (d) heat sensation, (e) and itching in the three groups of subjects. Only significant p‐values are reported with: * intra‐treatment significance versus baseline, ° significance between the product and the control in the Polish study (identical timepoint) and • significance between the Thai and Polish group at baseline. *, °: p < 0.05, **, °°: p < 0.01 and ***, °°°, •••: p < 0.001.
Additionally, skin hydration was increased by 15% (p < 0.001), while transepidermal water loss was decreased by 6% (p < 0.05) from D0 to D28. The global BoSS score also showed a reduction on D28, nearing statistical significance (−12%, p = 0.057). Finally, dermatologists reported good to very good product tolerance in 87.5% of the subjects.
Polish study
Compared to baseline, assessments by both dermatologists (Figure 1) and subjects (Figure 2) showed that after 28 days of product use, there was a significant (p < 0.001) reduction in redness (−20% and −28%, respectively), dryness (−51% and −53%, respectively), roughness (−67% and −62%, respectively) and scaling (−71% and −69%, respectively). Further reductions were observed after 56 days for redness (−30% and −41%, respectively), dryness (−78% and −76%, respectively), roughness (−88% and −83%, respectively) and scaling (−93% and −87%, respectively), which are all significant (p < 0.001 for all).
Significant differences (p < 0.01 to p < 0.001) were also evidenced when comparing the use of the product to that of a control cream. Upon product use, dermatologists' (Figure 1) and subjects' assessments (Figure 2) revealed lower redness (D28: −12% and −21%, D56: −15% and −27%, respectively), dryness (D28: −38% and −41%, D56: −67% and −65%, respectively), roughness (D28: −58% and −45%, D56: −76% and −66%, respectively) and scaling (D28: −53% and −49%, D56: −80% and −69%, respectively), compared to the control group.
The product use also led to significant decreases in all functional signs rated by subjects at D28 and D56 (Figure 3): tightness (−57% and −77%, respectively; p < 0.001 for both), tingling (−80% and −93%, respectively; p < 0.001 for both), pain (−96% and −100%, respectively; p < 0.01 for both), heat sensations (−71% and −81%, respectively; p < 0.001 for both) and itching (−64% and −73%, respectively; p < 0.001 for both).
At identical time points, lower clinical signs were also reported for the product compared to the control cream (Figure 3): tightness (D28: −50%, D56: −68%, p < 0.001 for both), tingling (D28: −72%, D56: −87%, p < 0.001 for both), pain (D28: −88%, D56: −100%, p < 0.05 for both), heat sensations (D28: −39%, p < 0.01; D56: −55%, p < 0.001) and itching (D28: −50%, D56: −47%, p < 0.001 for both).
Additionally, product use results in a significant (p < 0.001 for all) reduction of the stinging sensation and redness induced by lactic acid (Figure 4) at D28 (−53% and −9%, respectively) and D56 (−91% and −15%, respectively) compared to the control at baseline. Even though the control cream also induced significant decreases (D28 and D56 for the stinging sensation, D56 only for redness), the product had a greater effect at D28 on the stinging sensation only (−39%, p < 0.001) and, at D56, on both the stinging sensation and redness (−84%, p < 0.001; −8%, p < 0.01, respectively).
FIGURE 4.
Average lactic acid‐induced (a) stinging sensation given by subjects and (b) redness measured by Mexameter® in the two groups of the Polish study. Only significant p‐values are reported with: * intra‐treatment significance versus baseline and ° significance between the product and the control (identical timepoint). *: p < 0.05, °°: p < 0.01 and ***, °°°: p < 0.001.
Compared to baseline, the global BoSS score upon product application significantly decreased by 20% on D28 and 30% on D56 (p < 0.001 for both; Table 2). While the use of the control cream also reduced the BoSS global score (−6% on D28 and −11% on D56 compared to D0, p < 0.001 for both), the product demonstrated greater effectiveness in reducing the burden of SSS (−16% on D28 and −23% on D56, p < 0.001 for both). Finally, dermatologists reported that 100% of subjects tolerated the product very well, compared to 80% for the control cream.
TABLE 2.
BoSS sub‐scores and score results of the three groups studied.
| Control Poland | Product Poland | Product Thailand | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| BoSS score | p‐Value versus D0 a | BoSS score | p‐Value | BoSS score | p‐Value | |||||
| Versus D0 a | Versus control b | Versus D0 a | Versus product Poland b | |||||||
| Q1 | I have to consider my sensitive skin when deciding to buy clothing and underwear | D0 | 1.66 | – | 1.66 | – | 1.00 | 3.32 | – | <0.001 |
| D28 | 1.68 | 0.95 | 1.52 | 0.24 | 0.27 | 3.13 | 0.25 | <0.001 | ||
| D56 | 1.70 | 0.86 | 1.24 | <0.01 | <0.01 | – | – | – | ||
| Q2 | I have to consider my sensitive skin when deciding to buy cosmetics | D0 | 3.32 | – | 3.40 | – | 0.49 | 3.27 | – | 0.93 |
| D28 | 3.14 | <0.05 | 2.86 | <0.001 | 0.14 | 3.10 | 0.40 | 0.14 | ||
| D56 | 3.06 | <0.05 | 2.80 | <0.001 | 0.21 | – | – | – | ||
| Q3 | Having sensitive skin can prevent me from eating certain foods | D0 | 1.44 | – | 1.26 | – | 0.37 | 1.85 | – | <0.001 |
| D28 | 1.30 | 0.23 | 0.86 | <0.01 | <0.01 | 1.59 | 0.23 | <0.001 | ||
| D56 | 1.06 | <0.05 | 0.66 | <0.001 | <0.01 | – | – | – | ||
| Q4 | I've had to stop pursuing my hobbies, outdoor activities and vacation trips, because I have sensitive skin | D0 | 0.38 | – | 0.40 | – | 0.52 | 1.92 | – | <0.001 |
| D28 | 0.30 | 0.43 | 0.04 | <0.001 | <0.01 | 1.64 | 0.13 | <0.001 | ||
| D56 | 0.12 | <0.05 | 0.04 | <0.001 | 0.40 | – | – | – | ||
| Q5 | I can't be in air‐conditioned places for very long, because I have sensitive skin | D0 | 2.42 | – | 2.46 | – | 0.80 | 1.90 | – | <0.05 |
| D28 | 2.18 | 0.12 | 1.88 | <0.001 | <0.05 | 1.64 | 0.17 | 0.13 | ||
| D56 | 1.94 | <0.05 | 1.38 | <0.001 | <0.001 | – | – | – | ||
| Q6 | I can't tolerate the pollution in big cities, because I have sensitive skin | D0 | 1.42 | – | 1.38 | – | 0.90 | 2.15 | – | <0.001 |
| D28 | 1.14 | <0.05 | 0.76 | <0.001 | <0.05 | 1.82 | 0.11 | <0.001 | ||
| D56 | 1.06 | <0.05 | 0.74 | <0.001 | <0.05 | – | – | – | ||
| Q7 | Having a red face for no apparent reason or when I'm experiencing certain emotions makes me extremely embarrassed when I'm with other people | D0 | 2.74 | – | 2.64 | – | 0.45 | 1.85 | – | <0.001 |
| D28 | 2.62 | 0.33 | 2.32 | <0.01 | 0.15 | 1.56 | 0.09 | <0.001 | ||
| D56 | 2.42 | <0.05 | 1.82 | <0.001 | <0.001 | – | – | – | ||
| Q8 | My face is often red when I take pictures, so I avoid taking pictures of my face | D0 | 1.66 | – | 1.34 | – | <0.05 | 1.60 | – | 0.15 |
| D28 | 1.54 | 0.31 | 0.84 | <0.001 | <0.001 | 1.31 | 0.09 | <0.05 | ||
| D56 | 1.36 | <0.05 | 0.68 | <0.001 | <0.001 | – | – | – | ||
| Q9 | I can't wear accessory (bangle, necklace or bracelet) that is not made of gold | D0 | 1.52 | – | 0.96 | – | 0.08 | 2.47 | – | <0.001 |
| D28 | 1.44 | 0.18 | 0.84 | 0.17 | 0.06 | 2.15 | 0.19 | <0.001 | ||
| D56 | 1.42 | 0.18 | 0.74 | <0.05 | <0.05 | – | – | – | ||
| Q10 | My face becomes red when I exercise, walk quickly or walk upstairs | D0 | 3.36 | – | 3.38 | – | 0.76 | 2.60 | – | <0.001 |
| D28 | 3.16 | <0.05 | 2.66 | <0.001 | <0.01 | 2.10 | <0.05 | <0.05 | ||
| D56 | 2.96 | <0.01 | 2.18 | <0.001 | <0.001 | – | – | – | ||
| Q11 | I can't wear wool cloth that directly contact my skin | D0 | 2.36 | – | 2.70 | – | 0.14 | 2.42 | – | 0.25 |
| D28 | 1.88 | <0.01 | 1.92 | <0.001 | 0.83 | 2.05 | 0.06 | 0.67 | ||
| D56 | 1.90 | <0.01 | 1.64 | <0.001 | 0.31 | – | – | – | ||
| Q12 | I have to consider my sensitive skin when selecting clothes to wear in the morning | D0 | 1.38 | – | 1.54 | – | 0.64 | 2.57 | – | <0.001 |
| D28 | 1.42 | 0.67 | 1.24 | <0.05 | 0.15 | 2.23 | 0.13 | <0.001 | ||
| D56 | 1.38 | 1.00 | 0.98 | <0.001 | <0.01 | – | – | – | ||
| Q13 | I have to select laundry detergent myself, because some laundry detergents can cause me to have a skin reaction | D0 | 2.58 | – | 2.52 | – | 0.81 | 3.12 | – | <0.01 |
| D28 | 2.58 | 0.96 | 2.14 | <0.01 | <0.05 | 2.90 | 0.12 | <0.01 | ||
| D56 | 2.52 | 0.68 | 2.04 | <0.01 | <0.05 | – | – | – | ||
| Q14 | When I have to sleep away from home, I have to take my own soap and toiletries because I can't use somebody else's (soap or toiletries) | D0 | 3.54 | – | 3.42 | – | 0.98 | 3.05 | – | <0.05 |
| D28 | 3.52 | 0.85 | 3.48 | 0.44 | 0.71 | 2.82 | 0.33 | <0.01 | ||
| D56 | 3.50 | 0.68 | 3.40 | 0.63 | 0.68 | – | – | – | ||
| Global BoSS score | D0 | 29.78 | – | 29.06 | – | 0.43 | 34.12 | – | <0.01 | |
| D28 | 27.90 | <0.001 | 23.40 | <0.001 | <0.001 | 30.05 | 0.06 | <0.001 | ||
| D56 | 26.40 | <0.001 | 20.30 | <0.001 | <0.001 | – | – | – | ||
Abbreviation: BoSS, Burden of Sensitive Skin Syndrome.
Wilcoxon signed‐rank test (paired).
Wilcoxon rank‐sum test (unpaired).
Sensitivity comparison between the two populations
At D0, the Thai and Polish subjects significantly differed in the clinical signs scored by dermatologists (Figure 1). Polish subjects exhibited higher redness (+105%, p < 0.001) and dryness (+70%, p < 0.001), while Thai subjects showed higher roughness (+34%, p < 0.01). No difference was noted for scaling.
According to subjects' self‐assessments (Figure 2), baseline differences differed from dermatologists' observations. While no difference was found for redness, Thai subjects reported higher dryness (+25%, p < 0.001), roughness (+81%, p < 0.001) and scaling (+87%, p < 0.001) compared to Polish subjects.
Regarding subjects' assessments of functional signs (Figure 3), Thai subjects reported higher tingling (+245%, p < 0.001), pain (+678%, p < 0.001) and itching (+154%, p < 0.001) on D0 compared to Polish subjects. Finally, tightness and heat sensations were not significantly different between the Polish and Thai groups at baseline.
The BoSS questionnaire also highlighted differences between Thai and Polish subjects (Table 2). Thai subjects had a higher global score on D0 than Polish subjects (+17%, p < 0.01). These differences between the two groups primarily related to sensations (choice of clothing [Q1, Q12], accessories [Q9], activities [Q4] and the impact of pollution [Q6], p < 0.001 for all at each time point). Conversely, appearance‐related concerns were greater among Polish subjects, particularly those concerning facial redness (Q7: p < 0.001 at D28 and D56; Q10: p < 0.001 at D28 and p < 0.05 at D56).
DISCUSSION
Notwithstanding the differing study design—an open‐label evaluation in Thailand versus a double‐blind, placebo‐controlled assessment in Poland—both clinical evaluations demonstrated the efficacy of the dermo‐cosmetic cream in reducing SSS symptoms reported by dermatologists and subjects. The cream also alleviated functional signs and improved the quality of life of participants in both countries, despite the fact that the studies were primarily conducted between the end of the summer and the beginning of the winter. Indeed, the winter is known to alter the stratum corneum lipid composition and to be prone to SSS reactions [14, 18], which should have affected Polish subjects, considering the cold and dry climate they were subjected to by the end of the evaluation period.
These favourable results can be attributed to the enhanced skin hydration and barrier function evidenced in the Thai study, as well as to the reduced sensations during the lactic acid sting test (LAST) in the Polish study. Furthermore, dermatologists reported good to very good tolerance of the investigational dermo‐cosmetic cream in both studies, surpassing the tolerability of the control cream in the Polish study. Finally, it is noteworthy that subjects consistently rated clinical signs (redness, dryness, roughness and scaling) higher than the dermatologists, underscoring the subjective nature of skin sensitivity assessments.
The selection of Thailand and Poland for conducting the two studies was not driven by their representativeness of Asian or European populations. Instead, it was a direct request emanating from these two countries. Indeed, there is a paucity of research on the efficacy of dermo‐cosmetics for sensitive skin in the Thai population, with an interest in demonstrating the efficacy of such products. In Poland, a significant proportion of individuals with SSS apprehend dermo‐cosmetics given the potential of many of them to trigger SSS [4]. Consequently, there was a strong interest in demonstrating that a well‐designed dermo‐cosmetic formulation is well tolerated and outperforms basic hydrating creams.
The development of the tested product was guided by the principles of ecobiology, which views the skin as an ecosystem influenced by its environment and prioritizes the preservation of natural resources and mechanisms [19, 20]. When applied to dermatology, the skin is regarded as a dynamic ecosystem whose equilibrium should be preserved or restored, thus encouraging the development of tailored skincare products enriched with biomimetic ingredients [21, 22, 23].
The dermo‐cosmetic cream was formulated to exclude SSS triggering ingredients while restoring skin homeostasis. It closely resembles another dermo‐cosmetic product specifically designed to prevent and manage SSS, products that have already demonstrated their efficacy [24]. Both products contain identical active ingredients in similar proportions, differing only in their richness in biomimetic lipids, which is higher in the investigational product than in the cream evaluated in the previous study. Thus, the role of these ingredients will only be briefly summarized. In both products, the most abundant active ingredient is glycerin. Known to improve skin hydration, barrier function and mechanical properties of the stratum corneum, glycerin also promotes epidermal differentiation and alleviates cutaneous inflammation [25, 26, 27], offering multiple benefits to sensitive skin [28]. The two products also include multifunctional ingredients (squalane, glycerin dibehenate, glycerin behenate, glycol palmitate and cetyl palmitate) and humectants (pentylene glycol and caprylyl glycol), which contribute to skin comfort. They ensure immediate relief to sensitive skin by providing antioxidant protection against external aggressors (carnosine [29] and tocopherol [30]). Besides, the Salvia miltiorrhiza flower/leaf/root extract reduces neurogenic inflammation [24]. Finally, evaluations of reconstructed human epidermis revealed that, together, glycerin, butylene glycol, carnosine, tocopherol, Salvia miltiorrhiza flower/leaf/root extract and palmitoyl tetrapeptide‐10 also increase the expression of corneodesmosin (a marker of keratinocyte adhesion) and filaggrin (a marker of keratinocyte terminal differentiation), resulting in decreased skin permeability and improved skin barrier function (data not shown). Thus, by addressing the primary signs of SSS, these active ingredients and the cream significantly soothe SSS signs in both ethnic groups.
Beyond demonstrating the efficacy of the dermo‐cosmetic cream, a noteworthy aspect of this study is the inclusion of two distinct ethnic groups, assessed using identical evaluation methods. Differences in study design preclude an inter‐ethnic analysis of the product's effect; however, a baseline comparison between the two groups remains meaningful. The results indicate that Thai subjects consistently rated most clinical (dryness, roughness and scaling) and functional signs (tingling, pain and itching) higher than their Polish counterparts, a trend that closely aligned with dermatologists' evaluations. Conversely, Polish subjects exhibited higher levels of redness and dryness than their Thai participants and reported a greater burden of facial redness in their BoSS scores.
The heightened concern over facial redness among Polish participants may be partially explained by differences in inclusion criteria. The Polish protocol required a redness reaction to the LAST, potentially selecting individuals predisposed to such a reaction. However, a previous work has indicated that Caucasians often cite visual reactions as a primary manifestation of their sensitive skin [31]. Additionally, differences in skin pigmentation between light‐skinned Caucasians and fair‐skinned Thai participants may have amplified this discrepancy, as redness is often more obvious in individuals with lighter skin tones.
Another major difference between the two groups of subjects is that Thai participants consistently reported higher levels of clinical and functional signs than Polish subjects. They also reported higher global BoSS scores, particularly for sensation‐related questions. A previous study has highlighted that Asian populations are more likely to experience sensory effects such as burning or stinging [31]. Furthermore, Thai subjects are also more likely to be exposed to factors triggering sensitive skin reactions, including sun exposure, high temperatures and pollution—especially in a large city such as Bangkok, where the study was conducted [9, 31, 32]. Ethnic‐specific differences in triggers, such as heightened sensitivity to spicy foods, sudden temperature changes and wind exposure in Asian populations [9, 33], may also have played a role. Moreover, cultural differences between the two groups, though poorly understood, may have influenced subjective evaluations. However, studies have not consistently shown differences in the prevalence or self‐perception of SSS between Asian and Caucasian populations [9, 10, 11, 12, 15], suggesting that the variations observed in ethnic studies of SSS might primarily relate to a significant influence of external factors.
Finally, differences in skin structure and physiology may also have contributed to the observed results. Compared to Caucasian skin, Asian skin typically exhibits a thinner stratum corneum with lower levels of natural moisturizing factors, a weaker barrier function and a higher density of sweat glands. However, it tends to contain higher ceramide levels and greater dermal water content [7, 15, 34]. Interestingly, studies have found no significant differences in the neurosensory innervation of the skin between Caucasian and Asian populations [35]. Therefore, it is reasonable to assume that the differences in the prevalence and perception of sensitive skin between both ethnic groups are primarily driven by environmental factors (e.g. geographic location, season, altitude and sun exposure), cultural practices (cosmetic use, hygiene habits and dietary choices) and lifestyle factors (stress levels, sleep patterns, dietary habits and cosmetic products used) [6].
Nonetheless, limitations must be acknowledged. Despite common evaluation methods used in the Polish and Thai studies, the selection of Polish subjects was based on a positive reaction to the LAST test, which may have introduced a bias by excluding the full spectrum of the SSS population. Besides, the Thai study lacked a control group, limiting the ability to comprehensively assess the product's efficacy. The study durations also differed (28 days for Thailand vs 56 days for Poland). Future research would benefit from a more inclusive approach, taking advantage of fully consistent protocols across various populations, including studies involving African and/or Hispanic individuals with mixed phototypes and skin types.
CONCLUSIONS
This work is one of the few works investigating the efficacy of a dermo‐cosmetic skincare dedicated to SSS compared to a negative control group. Besides, by assessing SSS in two distinct populations, it highlighted differences in its signs and burden. Thai subjects experienced heightened sensitivity‐related sensations, whereas Polish participants exhibited more visible signs. Notwithstanding these differences, as well as obvious disparities in phototype, environment and cultural influences on SSS perception, the results demonstrated excellent tolerance and efficacy of the dermo‐cosmetic cream in alleviating SSS symptoms and improving the quality of life for affected individuals.
FUNDING INFORMATION
This study was financially supported by NAOS Ecobiology Company (Bioderma—Institut Esthederm—Etat Pur).
CONFLICT OF INTEREST STATEMENT
HP, SC, BC, MCB, CG, MS and EPM are/were employees of NAOS. EC, MS, WB, PC and SK received personal fees from NAOS during the conduct of the study.
Supporting information
Table S1
ACKNOWLEDGEMENTS
The authors would like to express their gratitude to Tatsama Tipburee and Kantika Plerntam‐makun from NAOS Thailand for their invaluable assistance in conducting the Thai study.
Polena H, Czaińska S, Cadars B, Chlebus E, Serafin M, Boonchai W, et al. Evaluation of the sensitive skin syndrome and the effect of a dermo‐cosmetic treatment in Thai and Polish subjects. Int J Cosmet Sci. 2026;48:70–82. 10.1111/ics.70017
DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available from the corresponding author upon reasonable request.
REFERENCES
- 1. Misery L, Ständer S, Szepietowski JC, Reich A, Wallengren J, Evers AWM, et al. Definition of sensitive skin: an expert position paper from the special interest group on sensitive skin of the International Forum for the Study of Itch. Acta Derm Venereol. 2017;97(1):4–6. 10.2340/00015555-2397 [DOI] [PubMed] [Google Scholar]
- 2. Raj N, Voegeli R, Rawlings AV, Doppler S, Imfeld D, Munday MR, et al. A fundamental investigation into aspects of the physiology and biochemistry of the stratum corneum in subjects with sensitive skin. Int J Cosmet Sci. 2017;39(1):2–10. 10.1111/ics.12334 [DOI] [PubMed] [Google Scholar]
- 3. Fluhr JW, Moore DJ, Lane ME, Lachmann N, Rawlings AV. Epidermal barrier function in dry, flaky and sensitive skin: a narrative review. J Eur Acad Dermatol Venereol. 2024;38(5):812–820. 10.1111/jdv.19745 [DOI] [PubMed] [Google Scholar]
- 4. Brenaut E, Barnetche T, Le Gall‐Ianotto C, Roudot AC, Misery L, Ficheux AS. Triggering factors in sensitive skin from the worldwide patients' point of view: a systematic literature review and meta‐analysis. J Eur Acad Dermatol Venereol. 2020;34(2):230–238. 10.1111/jdv.15985 [DOI] [PubMed] [Google Scholar]
- 5. Berardesca E, Farage M, Maibach H. Sensitive skin: an overview. Int J Cosmet Sci. 2013;35(1):2–8. 10.1111/j.1468-2494.2012.00754.x [DOI] [PubMed] [Google Scholar]
- 6. Talagas M, Misery L. Role of keratinocytes in sensitive skin. Front Med (Lausanne). 2019;6:108. 10.3389/fmed.2019.00108 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7. Wu Y, Wangari‐Olivero J, Zhen Y. Compromised skin barrier and sensitive skin in diverse populations. J Drugs Dermatol. 2021;20(4):s17–s22. 10.36849/JDD.2021.589c [DOI] [PubMed] [Google Scholar]
- 8. Chen W, Dai R, Li L. The prevalence of self‐declared sensitive skin: a systematic review and meta‐analysis. J Eur Acad Dermatol Venereol. 2020;34(8):1779–1788. 10.1111/jdv.16166 [DOI] [PubMed] [Google Scholar]
- 9. Jourdain R, de Lacharrière O, Bastien P, Maibach HI. Ethnic variations in self‐perceived sensitive skin: epidemiological survey. Contact Derm. 2002;46(3):162–169. 10.1034/j.1600-0536.2002.460307.x [DOI] [PubMed] [Google Scholar]
- 10. Fluhr JW, Darlenski R, Berardesca E. Ethnic groups and sensitive skin: two examples of special populations in dermatology. Drug Discov Today. 2008;5(2):e249–e263. 10.1016/j.ddmec.2008.06.004 [DOI] [Google Scholar]
- 11. Jourdain R, Maibach HI, Bastien P, De Lacharrière O, Breton L. Ethnic variations in facial skin neurosensitivity assessed by capsaicin detection thresholds. Contact Derm. 2009;61(6):325–331. 10.1111/j.1600-0536.2009.01641.x [DOI] [PubMed] [Google Scholar]
- 12. Lee E, Kim S, Lee J, Cho SA, Shin K. Ethnic differences in objective and subjective skin irritation response: an international study. Skin Res Technol. 2014;20(3):265–269. 10.1111/srt.12111 [DOI] [PubMed] [Google Scholar]
- 13. Jourdain R, Bastien P, de Lacharrière O, Rubinstenn G. Detection thresholds of capsaicin: a new test to assess facial skin neurosensitivity. J Cosmet Sci. 2005;56(3):153–166. 10.1111/j.1467-2494.2005.00289_1.x [DOI] [PubMed] [Google Scholar]
- 14. Misery L, Myon E, Martin N, Consoli S, Boussetta S, Nocera T, et al. Sensitive skin: psychological effects and seasonal changes. J Eur Acad Dermatol Venereol. 2007;21(5):620–628. 10.1111/j.1468-3083.2006.02027.x [DOI] [PubMed] [Google Scholar]
- 15. Rawlings AV. Ethnic skin types: are there differences in skin structure and function? Int J Cosmet Sci. 2006;28(2):79–93. 10.1111/j.1467-2494.2006.00302.x [DOI] [PubMed] [Google Scholar]
- 16. Misery L, Jourdan E, Abadie S, Ezzedine K, Brenaut E, Huet F, et al. Development and validation of a new tool to assess the Burden of Sensitive Skin (BoSS). J Eur Acad Dermatol Venereol. 2018;32(12):2217–2223. 10.1111/jdv.15186 [DOI] [PubMed] [Google Scholar]
- 17. Frosch PJ, Kligman AM. A method for appraising the stinging capacity of topically applied substances. J Soc Cosmet Chem. 1977;28(5):197–210. [Google Scholar]
- 18. Rogers J, Harding C, Mayo A, Banks J, Rawlings A. Stratum corneum lipids: the effect of ageing and the seasons. Arch Dermatol Res. 1996;288(12):765–770. 10.1007/BF02505294 [DOI] [PubMed] [Google Scholar]
- 19. Radman M. Ecobiological approach to research regarding ageing and diseases. Eur J Dermatol. 2019;29(S1):11–14. 10.1684/ejd.2019.3534 [DOI] [PubMed] [Google Scholar]
- 20. Dréno B. The microbiome, a new target for ecobiology in dermatology. Eur J Dermatol. 2019;29(S1):15–18. 10.1684/ejd.2019.3535 [DOI] [PubMed] [Google Scholar]
- 21. Callejon S, Giraud F, Larue F, Buisson A, Mateos L, Grare L, et al. Impact of leave‐on skin care products on the preservation of skin microbiome: an exploration of ecobiological approach. Clin Cosmet Investig Dermatol. 2023;16:2727–2735. 10.2147/CCID.S409583 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22. Bergera‐Virassamynaïk S, Ardiet N, Sayag M. Evaluation of the efficacy of an ecobiological dermo‐cosmetic product to help manage and prevent relapses of eyelid atopic dermatitis. Clin Cosmet Investig Dermatol. 2023;16:677–686. 10.2147/CCID.S401576 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 23. Fontbonne A, Teme B, Abric E, Lecerf G, Callejon S, Moga A, et al. Positive and ecobiological contribution in skin photoprotection of ectoine and mannitol combined in vivo with UV filters. J Cosmet Dermatol. 2024;23:308–315. 10.1111/jocd.15893 [DOI] [PubMed] [Google Scholar]
- 24. Polena H, Fontbonne A, Abric E, Lecerf G, Chavagnac‐Bonneville M, Moga A, et al. Management of triggering factor effects in sensitive skin syndrome with a dermo‐cosmetic product. J Cosmet Dermatol. 2024;23(12):4325–4333. 10.1111/jocd.16529 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 25. Fluhr JW, Gloor M, Lehmann L, Lazzerini S, Distante F, Berardesca E. Glycerol accelerates recovery of barrier function in vivo . Acta Derm Venereol. 1999;79(6):418–421. 10.1080/000155599750009825 [DOI] [PubMed] [Google Scholar]
- 26. Korponyai C, Szél E, Behány Z, Varga E, Mohos G, Dura Á, et al. Effects of locally applied glycerol and xylitol on the hydration, barrier function and morphological parameters of the skin. Acta Derm Venereol. 2017;97(2):182–187. 10.2340/00015555-2493 [DOI] [PubMed] [Google Scholar]
- 27. Páyer E, Szabó‐Papp J, Ambrus L, Szöllősi AG, Andrási M, Dikstein S, et al. Beyond the physico‐chemical barrier: glycerol and xylitol markedly yet differentially alter gene expression profiles and modify signalling pathways in human epidermal keratinocytes. Exp Dermatol. 2018;27(3):280–284. 10.1111/exd.13493 [DOI] [PubMed] [Google Scholar]
- 28. Fluhr JW, Darlenski R, Surber C. Glycerol and the skin: holistic approach to its origin and functions. Br J Dermatol. 2008;159(1):23–34. 10.1111/j.1365-2133.2008.08643.x [DOI] [PubMed] [Google Scholar]
- 29. Jukić I, Kolobarić N, Stupin A, Matić A, Kozina N, Mihaljević Z, et al. Carnosine, small but mighty‐prospect of use as functional ingredient for functional food formulation. Antioxidants (Basel). 2021;10(7):1037. 10.3390/antiox10071037 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 30. Kamal‐Eldin A, Appelqvist LA. The chemistry and antioxidant properties of tocopherols and tocotrienols. Lipids. 1996;31(7):671–701. 10.1007/BF02522884 [DOI] [PubMed] [Google Scholar]
- 31. Farage MA. Perceptions of sensitive skin: changes in perceived severity and associations with environmental causes. Contact Derm. 2008;59(4):226–232. 10.1111/j.1600-0536.2008.01398.x [DOI] [PubMed] [Google Scholar]
- 32. Le Gall‐Lanotto C, Verdin A, Cazier F, Bataille‐Savattier A, Guéré C, Dorr MM, et al. Road‐traffic‐related air pollution contributes to skin barrier alteration and growth defect of sensory neurons. Exp Dermatol. 2024;33(1):e15009. 10.1111/exd.15009 [DOI] [PubMed] [Google Scholar]
- 33. Farage MA. The prevalence of sensitive skin. Front Med (Lausanne). 2019;6:98. 10.3389/fmed.2019.00098 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 34. Iwuala C, Taylor SC. Structural and functional differences in skin of colour. Clin Exp Dermatol. 2022;47(2):247–250. 10.1111/ced.14892 [DOI] [PubMed] [Google Scholar]
- 35. Reilly DM, Ferdinando D, Johnston C, Shaw C, Buchanan KD, Green MR. The epidermal nerve fibre network: characterization of nerve fibres in human skin by confocal microscopy and assessment of racial variations. Br J Dermatol. 1997;137(2):163–170. 10.1046/j.1365-2133.1997.18001893.x [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Table S1
Data Availability Statement
The data that support the findings of this study are available from the corresponding author upon reasonable request.