Comprehensive assessment of the efficacy and safety of a clay mask in oily and acne skin

Abstract

BACKGROUND
Oily skin, characterized by excessive sebum production, can lead to acne and have psychosocial impacts due to changes in appearance. Recent research has shown interest in treatments for oil control, with kaolin and bentonite emerging as promising options. Despite their potential, comprehensive studies on these ingredients are still in the nascent stages.

AIM
This study aimed to assess the efficacy of a clay mask (La Roche‐Posay Effaclar Sebo‐Controlling Mask) in reducing skin oiliness and acne, and its safety for use.

METHODS
In this study, 75 adults with oily or combination skin were enrolled and provided with a clay mask for twice‐weekly use over 4 weeks. Clinical assessments, using instruments like Sebumeter, Vapometer, and Corneometer, were conducted at baseline, and after 1, 2, and 4 weeks, evaluating acne lesions, skin irritation, sebum content, and skin hydration. Participant self‐assessment questionnaires were also utilized for subjective evaluation. Statistical analyses were performed accordingly.

RESULTS
The study revealed significant improvements in acne‐related outcomes, sebum content, skin evenness, stratum corneum water content, and transepidermal water loss following the application of the clay mask. Pore area and porphyrin area showed no significant changes. Tolerance assessment showed reduced dryness and irritation, with self‐assessment indicating high product acceptability and perceived oil control effectiveness.

CONCLUSION
This study demonstrated the clay mask's efficacy in managing acne and oily skin, improving hydration and texture. Significant improvements in skin parameters and high product safety were observed, supporting its suitability.

Full text

Received: 16 August 2023 Accepted: 17 October 2023
DOI: 10.1111/srt.13513
ORIGINAL ARTICLE
Comprehensive assessment of the efficacy and safety of a clay
mask in oily and acne skin
Xianghua Zhang1Zhongxing Zhang1Han Tao1Xiaofeng He2Kungchi Hsu2
Wenna Wang2Xiaofeng Fang2Andrew Steel2
1L’Oréal, Shanghai, China
2Research and Innovation Center, L’Oréal
China, Shanghai, China
Correspondence
Xianghua Zhang, L’Oréal, Shanghai, China.
Email: succi.zhang@loreal.com
Abstract
BACKGROUND:: Oily skin, characterized by excessive sebum production, can lead to
acne and have psychosocial impacts due to changes in appearance. Recent research
has shown interest in treatments for oil control, with kaolin and bentonite emerging as
promising options. Despite their potential, comprehensive studies on these ingredients
are still in the nascent stages.
AIM: This study aimed to assess the efficacy of a clay mask (La Roche-Posay Effaclar
Sebo-Controlling Mask) in reducing skin oiliness and acne, and its safety for use.
METHODS: In this study, 75 adults with oily or combination skin were enrolled and
provided with a clay mask for twice-weekly use over 4 weeks. Clinical assessments,
using instruments like Sebumeter, Vapometer, and Corneometer, were conducted at
baseline, and after 1, 2, and 4 weeks, evaluating acne lesions, skin irritation, sebum con-
tent, and skin hydration. Participant self-assessment questionnaires were also utilized
for subjective evaluation. Statistical analyses were performed accordingly.
RESULTS: The study revealed significant improvements in acne-related outcomes,
sebum content, skin evenness, stratum corneum water content, and transepidermal
water loss following the application of the clay mask. Pore area and porphyrin area
showed no significant changes. Tolerance assessment showed reduced dryness and
irritation, with self-assessment indicating high product acceptability and perceived oil
control effectiveness.
CONCLUSION: This study demonstrated the clay mask’s efficacy in managing acne
and oily skin, improving hydration and texture. Significant improvements in skin
parameters and high product safety were observed, supporting its suitability.
KEYWORDS
acne, clay mask, oily skin, porphyrin counts, sebum control
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided
the original work is properly cited.
© 2023 Loreal China. Skin Research and Technology published by John Wiley & Sons Ltd.
Skin Res Technol. 2023;29:e13513. wileyonlinelibrary.com/journal/srt 1of7
https://doi.org/10.1111/srt.13513

2of7 ZHANG ET AL.
1INTRODUCTION
Oily skin, characterized by an overproduction of sebum, is a
widespread dermatological condition affecting a significant por-
tion of the global population. Studies suggest that oily skin can lead
to a shiny complexion, enlarged pores, and is often associated with
acne due to the blockage of pores.1These manifestations not only
affect an individual’s appearance but can also contribute to lowered
self-esteem and psychological distress.2Despite the prevalence of oily
skin, finding an effective treatment remains a substantial challenge in
dermatology. Any treatment deemed successful must strike a balance
between controlling excess oil production, maintaining skin hydration,
and minimizing adverse effects. Moreover, environmental factors such
as high temperatures can exacerbate sebum production, adding to the
complexity of treating oily skin.3
Current treatments for oily skin, ranging from topical applications
such as retinoids and salicylic acid to more advanced procedures like
chemical peels and laser therapy, present their own set of challenges.4
Despite their efficacy, they are often associated with side effects
like dryness and irritation and typically necessitate ongoing use to
maintain results.5,6
In light of the limitations of existing treatments, recent years have
seen an uptick in research into less invasive treatments for oily
skin. Notably, certain ingredients, including kaolin and bentonite, have
shown promise in controlling oiliness without excessively drying the
skin.7Kaolin and bentonite are known for their strong oil-absorbing
and impurity-extracting abilities, which may be particularly beneficial
for severe cases of oily skin and acne.8Additionally, many clay masks
incorporate other oil-controlling ingredients, such as activated char-
coal, recognized for its high absorptive capacity and ability to draw out
impurities from the skin.9However, there is a lack of comprehensive
studies examining the effects of these ingredients in combination over
extended periods, making it important to understand their impact on
the skin’s oil production and overall health.
In this study, we aim to assess the efficacy and safety of a clay mask,
enriched with cellulobeads, kaolin, bentonite, thermal spring water,
and vitamin B5 (panthenol), improving the skin condition and acne in
the management of oily skin, with great tolerance and safety.
2METHODS
2.1 Study design and subjects
This study enrolled adults (70% women) aged 18–45 years old with
either oily or combination, with at least 50% self-declared sensitive
skin (baseline sebum level ≥100 μg/cm2) recruited in Shanghai, China,
in March 2023.
Inclusion Criteria: The study included participants who were aged
between 18 and 45 years, had a skin type classified as either oily or
combination, and self-declared sensitive skin at least 50% of the time.
Participants also had to have an open and closed comedone on the face
or nose, with mild or moderate acne rated less than or equal to 2 on
the ISGA scale. Furthermore, they had to be participants not currently
participating in any other study involving the test area (face) during
the research period, and those who had not participated in any similar
study involving the test area (face) in the past month.
Exclusion criteria: Participants were excluded from the study if
they had any chronic disease that could interfere with the test, such
as asthma, insulin-dependent diabetes, lupus, rheumatoid arthritis, or
other immune/autoimmune diseases. The use of any prescription or
over-the-counter medication applied to the skin of the test area (face),
such as anti-acne or hydrocortisone products, was also a disqualify-
ing factor. Those who had been diagnosed with cancer within the past
year, or had received cancer treatment within that period, or were
currently taking preventive medication related to cancer were also
excluded. Participants with any skin condition (such as eczema, pso-
riasis, rosacea), infection or injury in or around the test area (face),
and those who are pregnant, planning to become pregnant during the
study period, or currently nursing were also excluded from the study.
All subjects provided signed informed consent before enrollment.
2.2 Intervention
Participants were given a clay mask for facial treatment. Initial use
of the product was conducted at the research center, where partic-
ipants were guided on proper application (let the clay mask stay for
5–10 min and then wash with water) and subsequently asked to com-
plete a questionnaire. The mask was then distributed for home use,
with instructions for twice-weekly applications.
2.3 Clinical assessment
In a controlled environment, maintaining uniform temperature and
humidity, a series of clinical assessments were performed on partici-
pants at baseline, and after 1, 2, and 4 weeks of the intervention. Prior
to each assessment, participants acclimated to the environment for 30
min after washing their faces, excluding the forehead.
Dermatologists conducted a comprehensive evaluation of acne
lesions, counting closed comedones (whiteheads), open comedones
(blackheads), inflammatory papules, and pustules. Additionally, a tol-
erance test was conducted to assess the product’s potential skin
irritation and subjective discomfort effects. These effects included ery-
thema, edema, dryness, scaling, and sensations of burning, stinging,
itching, tightness, and tingling. Evaluations were carried out prior to
product use and after each individual use.
2.4 Instrumental assessment
Sebum content was assessed using the Sebumeter SM-815 (Courage
& Khazaka, Germany). The device was applied once to the forehead,
providing a reading that represented the sebum content of the skin in
that area.

ZHANG ET AL.3of7
NS
*** ***
***
40
42
44
46
48
50
52
54
56
58
W0TimW1W2W4
Skin hydraon
Test me
**
***
***
***
15
16
17
18
19
20
21
22
23
24
W0 Tim W1 W2 W4
TEWL
Test me
***
*** ***
***
30
50
70
90
110
130
150
170
W0TimW1W2W4
Sebum content
Test me
*
NS
**
1.45
1.5
1.55
1.6
1.65
1.7
1.75
W0 Tim W1 W2 W4
Skin Evenness
Test me
NS
NS
NS
*
24
24.5
25
25.5
26
26.5
27
27.5
28
28.5
29
W0 Tim W1 W2 W4
Porphyrin counts
Test me
**
***
***
***
4
5
6
7
8
9
10
11
12
13
14
W0 Tim W1 W2 W4
Acne number
Test me
(A) (B)
(C) (D)
(E) (F)
FIGURE 1 Changes from baseline in investigator global assessment (IGA) score of acne severity (A), Skin hydration (B), TEWL (C), Sebum
content (D), Skin evenness (E), Porphyrin counts (F), Acne number.
A Vapometer (Delfin, Finland) was employed to evaluate Transepi-
dermal Water Loss (TEWL). Three separate measurements were taken
and subsequently averaged to obtain a representative value of the
skin’s water loss rate.
Hydration level of the stratum corneum, the outermost layer of
the skin, was determined using a Corneometer CM 825 (Courage
+Khazaka, Germany). The device was used to take three separate
measurements, the average of which provided the hydration level of
the stratum corneum.
Frontal images of the face were captured using VISIA-CR (Can-
field, USA). These images were then processed using IPP software,
which provided data regarding the proportion of pore area, skin color
evenness, and the proportion of porphyrin area.
2.5 Self-assessment
Subjective discomfort was assessed by having the participants rate
their sensations of burning, stinging, itching, tightness, and tingling on
a scale from 0 to 3. These scores corresponded to various degrees of
discomfort, ranging from “unnoticeable” to “very noticeable,”.
Furthermore, participants completed questionnaires at the
research center. These questionnaires were administered initially
after the first use of the product at the center and subsequently after
each assessment session (Immediate post-treatment, Week 1, Week
2, and Week 4). The questionnaires provided additional insights into
the participants’ subjective experiences, perceptions, and satisfaction
levels with the product.

4of7 ZHANG ET AL.
01-W0 01-Tim 01-W1 01-W2 01-W4
Skin
evenness
Pore
FIGURE 2 VISIA-CR analysis illustration
for an average case: Evaluation of skin
evenness and pore characteristics from
baseline (T0) to week 4 (W4).
2.6 Statistical analysis
Descriptive statistics, including count, mean, standard deviation, min-
imum, and maximum values, were generated for all measured val-
ues using Microsoft Excel. This provided an initial understanding
of the data distribution and central tendencies. For comparison of
metric data before and after product use, the Shapiro-Wilk Test
was conducted using SPSS software to assess the normality of the
data change values. If the data followed a normal distribution, a
paired t-test was employed. If not, the Wilcoxon rank-sum test for
two related samples was utilized. The level of significance, α,was
set at 0.05 for these tests. Ranking data were compared before
and after product use employing the two related samples rank-sum
test. Comparisons between the test and control areas were con-
ducted using a paired sample t-test or rank-sum test, depending on
the nature of the data. Here, too, the level of significance, α,was
set at 0.05.
3RESULTS
3.1 Study flowchart
A total of 75 participants were screened, of whom 55 participants
were intended for both clinical assessment and questionnaire feed-
back and 20 participants intended for questionnaire feedback only.
This screening process led to the enrollment of 65 participants, com-
prising 45 participants for the clinical assessment/questionnaire group
and 20 participants for the questionnaire-only group. The study was
successfully completed by 60 participants in total, with 40 participants
from the clinical assessment/questionnaire group and 20 participants
from the questionnaire-only group, whose data were included for
subsequent analysis.
3.2 Baseline patient characteristics
Mean ages of the participants were 38.13 ±6.82 and 38.62 ±6.58
years in the clinical assessment/questionnaire and questionnaire-only
groups, respectively; 68.30% of the participants were women, and
85.00% had self-assessed sensitive skin. Lipid Index at baseline were
154.60 ±32.18 and 157.25 ±25.86 μg/cm2;ISGAScoreswere
1.40 ±0.50 and 1.30 ±0.47; Sensitive skin self-rating score were
5.70 ±1.26 and 5.65 ±0.99, respectively.
3.3 Treatment efficacy
In relation to acne-related outcomes, both closed comedones and
open comedones exhibited significant reductions immediately post-
treatment with improvement rates of 5.06% and 4.81% respectively.
The reductions became more pronounced over the weeks, with rates
of 25.75% and 25.38% at week 1, 32.18% and 47.12% at week 2, and
46.44% and 65.77% at week 4 (all p<0.001).
There was no significant alteration in the stratum corneum water
content immediately after treatment (p=0.067). However, signifi-
cant increases were observed at week 1 (14.33%, p<0.001), week
2 (16.51%, p<0.001), and week 4 (29.65%, p<0.001), suggesting a
cumulative hydrating effect of the product over time.
An immediate post-treatment reduction of 3.09% in TEWL was
recorded (p=0.009), which signifies an enhancement in the skin bar-
rier function. This reduction persisted and intensified over the weeks,
with reductions of 11.00% at week 1, 16.32% at week 2, and 20.41% at
week 4 (all p<0.001).
Following the immediate post-treatment, there was a markedreduc-
tion in skin oiliness by 68.97% (p<0.001). This decline continued with
rates of 24.26% at week 1, 24.22% at week 2, and 29.90% at week 4 (all
p<0.001).
An immediate improvement of 3.64% in skin evenness was noted
post-treatment (P =0.030). Further improvements were observed at
week 2 (7.88%, p=0.021) and week 4 (7.27%, p=0.018). Lastly, the
proportion of the porphyrin area showed a slight increase over the 4-
week duration. This increase was not statistically significant (Figure 1,
Figure 2).
3.4 Tolerance assessment
Objective assessment, including erythema, edema, dryness, and
desquamation, showed a significant decrease in dryness and an over-

ZHANG ET AL.5of7
TAB LE 1 Result of Objective Irritation Parameters Assessment (60 Subjects).
W0 Tim W1 W2 W4
erythema 22 (0,0,2) 17 (0,0,2) 16 (0,0,1) 20 (0,0,1) 15 (0,0,1)
edema 1 (0,0,1) 1 (0,0,1) 0 (0,0,0) 0 (0,0,0) 0 (0,0,0)
dryness/scaling 37 (0,1,2) 16 (0,0,1)*** 10 (0,0,1)*** 12 (0,0,1)*** 7 (0,0,1)***
desquamation 1 (0,0,1) 1 (0,0,1) 1 (0,0,1) 5 (0,0,1)* 0 (0,0,0)
Total Score 61 (0,1,3) 35 (0,0,3)*** 27 (0,0,3)*** 37 (0,0,3)** 22 (0,0,2)***
TAB LE 2 Result of subjective discomfort parameters assessment (60 Subjects).
W0 Tim W1 W2 W4
burning 3 (0,0,1.5) 1 (0,0,1) 0 (0,0,0) 0 (0,0,0) 0 (0,0,0)
stinging 1 (0,0,0.5) 0 (0,0,0) 0(0,0,0) 0 (0,0,0) 0 (0,0,0)
itching 13.5 (0,0,1.5) 1(0,0,0.5)*** 1.5 (0,0,0.5)*** 0 (0,0,0)*** 0.5 (0,0,0.5)***
tightness 47.5 (0,1,2) 15.5 (0,0,2)*** 11.5 (0,0,1)*** 5 (0,0,1)*** 4.5 (0,0,1)***
tingling 0 (0,0,0) 0 (0,0,0) 0(0,0,0) 0.5 (0,0,0.5) 0 (0,0,0)
all reduction in total irritation from immediate post-treatment to week
4. Subjective assessment, including burning, stinging, itching, and tight-
ness sensations, revealed significant reductions in itching and tightness
from immediate post-treatment to week 4. The total discomfort score
also significantly decreased during this period. The results are shown in
Ta b l e 1and Table 2.
3.5 Self-assessment
Immediately after application, over 90% of participants found the
product easy to apply and wash off, with 96.7% and 90% agreement
respectively. Notably, 100% of the participants reported the product’s
oil control effectiveness after 1 week of use. This perceived benefit
was consistently reported across week 2 and week 4, with 100% and
98.3% of participants, respectively. In terms of skin comfort, 91.7%
of participants at week 1 and 95% at week 4 reported a lack of skin
tightness or dryness. By the end of the study at week 4, other posi-
tive skin changes were reported by over 95% of participants, including
reduced visibility of skin flaws, improved skin appearance, and reduced
skin discomfort.
4DISCUSSION
This study evaluated the efficacy, safety and tolerance of a clay mask,
enriched with cellulobeads, kaolin, bentonite, thermal spring water,
and vitamin B5 (panthenol), addressing concerns related to acne and
oily skin, while promoting skin hydration and overall texture improve-
ment. Various instrumental methods, clinical assessment by a blinded
dermatologist and self-assessment were used to evaluate the skin
response to the clay mask.
It was found that the number of both open and closed come-
dones, sebum content, skin evenness, stratum corneum water content,
and transepidermal water loss were all significantly improved, with
changes noticeable from the immediate post-treatment period and
sustained throughout the course of the study. These results suggested
that the studied clay mask is effective in mitigating prominent skin
issues such as acne, hyperseborrhea, and skin dehydration, indicat-
ing immediate skin barrier enhancement. Various clinical trials have
demonstrated the efficacy of commonly used clay minerals, including
kaolin and bentonite for oily skin management, supporting the cur-
rent results.10–12 Kaolin and bentonite are hydrated Aluminum Silicate
and Aluminum Magnesium Silicate, respectively. They have the abil-
ity to absorb oil due to their large surface area, porosity, ionic charge,
which make them effective ingredients in products designed to control
oiliness.13 In addition, the studied clay mask contained cellulobeads.
The hydrophilic microspheres possess a high capacity for moisture
absorption, which can aid in retaining the skin’s moisture balance, a
characteristic that contributed to the significant increase in stratum
corneum water content observed throughout the study.14 Further-
more,theirsmallsize(10μm) and high bulk density (11.6 g/in3) suggest
that they could provide a dense, uniform coverage on the skin surface,
absorbing extra oil and potentially enhancing the mask’s adherence and
performance.
The alteration of sebum composition by the oil-absorbing ingre-
dients present in the clay mask plays a critical role in managing acne
development.15 The mask’s key constituents, kaolin and bentonite,
can effectively extract surplus oil from the skin, thereby attenuating
sebum production and decreasing the likelihood of pore blockage.
Additionally, the cellulobeads help regulate the skin’s moisture
balance, mitigating any potential drying effects of the clays and pre-
venting a compensatory overproduction of sebum. Thermal spring
water, another ingredient, offers soothing and anti-inflammatory ben-
efits, which could assist in alleviating acne-associated inflammation
and promoting skin healing.16 Furthermore, the mask incorporates
5% vitamin B5 (panthenol), known for its role in skin soothing and
anti-inflammatory properties, could potentially contribute to the

6of7 ZHANG ET AL.
acne-reducing effects of the product.17 Combined, they soothe the
skin by decreasing interleukin (IL)−1α, which is an inflammatory factor
highly expressed in comedones.18
Throughout the study, both objective and subjective assessments
consistently indicated the safety of the clay mask. The signifi-
cant decrease in skin dryness and total irritation score, along with
reductions in sensations of itching and tightness from immediate
post-treatment to week 4, reflect the product’s tolerability. These
results, coupled with the observed improvements in skin condi-
tion such as decrease in TEWL, suggest that the clay mask is safe
and suitable.
The self-assessment results further reinforced the efficacy and
acceptability of the clay mask. The majority of participants reported
ease of application and wash-off immediately after product use,
highlighting the practicality of the product. Remarkably, after a week
of use, all participants perceived the product’s oil control effectiveness,
suggesting a tangible, positive impact on skin oiliness. Furthermore,
by the end of the study, over 95% of participants reported noticeable
improvements in skin appearance, reduced visibility of skin flaws, and
diminished skin discomfort.
In contrast to a previous clay mask study,10 which focused on acute
effects over a short duration of 2 h, the present study extended the
evaluation period to 4 weeks. This longer timeframe provides a more
comprehensive understanding of clay mask’s sustained benefits and
potential effects on skin health. The extended duration not only cap-
tures immediate post-treatment results but also offers insights into the
cumulative benefits of regular usage.
While our study provides promising evidence for the efficacy of the
clay mask, some limitations should be acknowledged. The lack of a sig-
nificant decrease in porphyrin levels despite the reduction in oil levels
is a notable observation from our study.One possible explanation could
be that the skin microbiota, which includes the porphyrin-producing
bacteria (Propionibacterium), is resilient and can survive for some time
even after oil levels decrease. Alternatively, the clay mask may have
some effects on the skin microbiota that influence porphyrin produc-
tion, as shown in a previous study that C. acnes might gain nutrition
contained in the mask, such as glycerol, free fatty acids, especially in
sebum-deprived conditions, thus increasing the porphyrin.19 Further
studies are needed to explore these possibilities and understand the
complex interplay between skincare products, skin oil levels, and the
skin microbiota.
In conclusion, this study provides compelling evidence for the effi-
cacy and safety of the clay mask in managing skin conditions related to
acne and oiliness, while promoting skin hydration and texture improve-
ment. The clay mask demonstrated significant improvements in key
skin parameters including the reduction of both open and closed
comedones, sebum content, and transepidermal water loss, alongside
enhancements in skin evenness and stratum corneum water content.
Importantly, these improvements were observed from the immedi-
ate post-treatment period and were sustained throughout the study.
Furthermore, both objective and subjective tolerance assessments
indicated high safety and acceptability of the clay mask, suggesting its
suitability.
ACKNOWLEDGMENT
This study was funded by L’Oreal.
CONFLICT OF INTEREST STATEMENT
No conflict of interest was reported by the authors.
DATA AVAILABILITY STATEMENT
No.
ORCID
Han Tao https://orcid.org/0009-0001- 3996-3424
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How to cite this article: Zhang X, Zhang Z, Tao H, et al.
Comprehensive assessment of the efficacy and safety of a clay
mask in oily and acne skin. Skin Res Technol. 2023;29:1–7.
https://doi.org/10.1111/srt.13513