364 JOURNAL OF COSMETIC SCIENCE
phototypes I–III.17 In a genome-wide association study involving 22,952 subjects, Chang
and colleagues determined that rosacea is associated with several HLA alleles.18 This is in
line with the inflammatory nature of the syndrome. In a study involving 1,000 individuals
in Korea, 56.8% of whom had sensitive or very sensitive skin, Kim and colleagues found
that the group with SSS was more than 3 times more likely to suffer from acne, atopic
dermatitis, and facial blushing, and they were over 2 times more likely to suffer from
seborrheic dermatitis compared with the nonsensitive group.19 Brenaut and colleagues
found a similar result in an Indian population.20 In a study involving more than 3,000
individuals, subjects with SSS were 2–4 times more likely to report atopic dermatitis, acne,
psoriasis, vitiligo, rosacea, or contact dermatitis compared with the nonsensitive group.20
Sensitive skin has also been linked to sensitive eyes and eyelids, along with irritable bowel
syndrome.26,27 It is proposed that these conditions may be related to the neurosensory
dysfunctions identified in SSS (i.e., hyperexcitability of nerve endings, hyperactivation of
sensor proteins resulting from upregulation of TRP channels, and alterations in nerve fiber
density).26 The histological findings and clinical signs of small-fiber impairment with SSS
are similar to those experienced in small-fiber neuropathy.28
As part of a genome-wide association study, Farage et al. evaluated 23,426 subjects’ responses
and found that individuals with SSS reported other skin complaints—specifically, contact
dermatitis, freckles, atopic dermatitis, acne, and seborrheic dermatitis.25 These authors
found a connection between SSS and several specific loci also associated with genes for
rosacea, pigmentation, and skin cancer.25
OTHER HOST-RELATED FACTORS: AGING AND HORMONAL FLUCTUATIONS
Aging can be another physiologic factor in sensitive skin. As an individual ages, the skin
changes as it becomes thinner and drier, and it replaces itself at a slower rate.29 The elderly
skin is also more prone to higher permeability but a reduced elasticity, tensile strength,
vascularization, and cellularity.29 These physiological changes might lead one to conclude
that older skin is more susceptible to irritant effects and more likely to be sensitive. However,
clinical assessments using known irritant materials suggest that skin irritation susceptibility
generally decreases with age, as does the capacity to produce visible physiological signs of
dermatological irritation.9,29–32 Several studies have shown that the prevalence of SSS in older
Table II
Some Skin Comorbidities Associated with SSS
Comorbidity condition
Rosacea17,20,21
Acne19,20
Atopic dermatitis (eczema)5,19,20
Atopic22–24
Blushing19
Seborrheic dermatitis (dandruff)19,20,25
Psoriasis20
Vitiligo20
Contact dermatitis25
Freckles25
Sensitivity of the corneas and eyelids26
Irritable bowel syndrome26

365 Sensitive Skin Syndrome
individuals is no different or less than in younger individuals.19,23,33,34 A 2010 study with
1,039 individuals evaluated SSS at several body sites in the United States.29 No consistent
pattern with age was seen when subjects were asked about sensitive skin in general (of the
face or body, specifically). However, genital area skin sensitivity demonstrated an increase
from 53% in subjects ≤30 years old to 66% in subjects ≥50 years old (Figure 1). This
difference was mainly due to the females in the study.
Another critical factor is the impact of hormonal fluctuations during the different consumer
life stages on skin sensitivity. In both the dermis and epidermis, the skin has highly sensitive
estrogen receptors, and variation of female hormones can have an impact on the skin.38
Decreased estrogen levels can adversely affect barrier function, elasticity, blood circulation,
and vasomotor function. Farage’s study, which included 1,039 individuals, demonstrated that
the menstrual cycle was contributing to unpleasant genital skin in 61% of women with SSS
and 40% of women with nonsensitive skin (p 0.00001).37 Falcone and colleagues reported
that women with more intense perimenstrual symptoms perceived their skin as more sensitive
during some phases of the menstrual cycle compared with women who had lower intensity
symptoms (p =0.002).39 Furthermore, 70% of postmenopausal women claimed they perceived
that SSS caused their skin sensitivity to increase after menopause.39 In general, among women
with SSS, products used for menstrual protection and hygiene have been shown to trigger
significantly greater symptoms than among women in the nonsensitive group.37
PSYCHOLOGICAL EFFECTS OF SKIN DISEASE
As mentioned previously, individuals with SSS are more likely to also suffer from other skin
disorders and comorbidities. While most skin diseases are not associated with substantial
functional impairment, they can have significant adverse effects on the psychological health
of sufferers and the overall quality of life (QoL).40 Furthermore, the presence of certain other
psychological conditions—such as depression, anxiety, stress, and sleep disorders—can lead
Figure 1. Age and gender effect on prevalence of sensitive genital skin. Responders were asked if they had
sensitive skin (“slight,” “moderate,” or “very”).35,36 MH chi-square was used to test for correlations between
perceptions of sensitive skin and age for responders overall and for each gender. Adapted with permission from
reference 37. Copyright 2019 Frontiers Media.