Our analysis of two independent cohorts demonstrates that a sudden discontinuation of daily moisturizing creams leads to significant but temporary symptoms that suggest relevant dehydration of the facial skin. In the cohort I of 17–25-year-old women during winter, typical symptoms of dry skin already appeared on day 1 after treatment discontinuation. Both subjective and objective assessments confirmed the observed significantly increased effects. Additionally, in summer (cohort II), dryness of facial skin was significantly higher only in the 15–20-year-old participants.
To the best of our knowledge, this is the first clinical study analysing whether discontinuation of facial moisturizing cream leads to skin changes in the real-world setting. The aim was to evaluate whether the skin recovers to its original condition and, if so, how long this recovery process takes.
Knowledge about benefits and disadvantages of long-term therapy with moisturizers influencing the skin barrier function and the skin’s reaction to a sudden stop of this treatment is still insufficient [1]. A standard facial moisturizer consists of approximately 80% water, 5% humectants, 4% emollients/occlusives, 6% emulsifiers, 2% silicate, 0.3% thickener, 0.4% preservative, and 0.2% fragrance. Topical moisturizers are able to deposit lipids and other permeability barrier-enhancing ingredients within the SC and provide occlusion causing a more immediate reduction in TEWL [11]. Natural moisturizing factor, a collection of humectant substances based on the catabolism of filaggrin, serves as a successful component in moisturizers [12]. By inducing changes in the superficial and deep layers of the epidermis, the use of over-the-counter (OTC) moisturizers may have multiple beneficial, but also potentially negative effects on the skin [5, 7, 13, 14]. Improvements in barrier function of the SC with topical moisturizers measured by TEWL and confocal Raman spectroscopy have frequently been reported [7, 15, 16]. An increased TEWL occurs under lipid-free gel, whereas adding lipids results in an increased effectiveness regarding skin dryness [17]. Long-term moisturizing treatment may lead to reduced baseline sebum levels in Caucasians, which makes the skin more vulnerable including increased skin susceptibility to irritants [18]. Consistent with our results, regardless of the season, a previous study has shown an immediate decreasing hydration score after stopping moisturizer application [19].
Various exogenous factors such as climate, seasons and extreme bathing habits have been proposed to be linked to dry skin [20, 21]. Despite external challenges, the renewal process can mostly compensate to maintain the skin barrier’s protective function [12]. In accordance with our data, we noticed only minor seasonal differences in skin recovery time. An essential part of the homeostatic function of the SC in every individual is the maintenance of skin hydration regardless of the presence of skin disease or normal skin [22]. In contrast, seasonal variation of catalase activity in human SC, with lower activities in summer and higher activities in winter, suggest seasonal differences. Hellemans et al. detected that sun exposure results in disturbed antioxidant enzyme activity leading to increased vulnerability to oxidative damage in the SC barrier components with low activities in summer and higher activities in winter [22]. They indicate that the recovery of the catalase activity shows seasonal variation with an age-dependent recovery being less in younger adults compared to older adults.
Former studies showed that TEWL and consequently the visual dryness are significantly higher in winter than in summer. The SC lipids (total and individual ceramides, total fatty acids and cholesterol) are higher in summer compared to winter. Further seasonal functional changes of the skin barrier include significant higher indicators of skin inflammation, the ratio of interleukin-1 receptor antagonist (IL-1ra) to interleukin-1α (IL-1α), in the winter [23]. We assume that healthy skin’s greater need for moisturizing in winter explains why the facial dryness was more intense in our winter study.
Older persons’ skin reacts less intensely than young persons’ skin regarding changes caused by interruption of topical moisturizer. Except for the significantly increased overall mean dryness score in aging skin over a 7-day period, there were no further significant differences between the interventional and control sides in older participants. We conclude that the decreased lipid and intrinsic moisturization of aged skin might be less quickly downregulated during treatment with moisturizers than that of the young skin. An age-dependent decrease in ceramides content is well known and correlates with skin dryness and loss of elasticity at an advanced age [12, 24,25,26].
Our study demonstrates that young skin is not persistently dependent on a moisturizer as demonstrated by a skin recovery time of 6 days in winter and 11 days until reaching the skin’s condition at baseline and of 21 days until matching the control side in summer. Surprisingly, the control side for young patients becomes better over the observed time period in the summer study, which explains our two definitions of recovery time above. We assume that this is a bias from the participants as they might see the moisturized side has less skin symptoms over time or they might be less stringent in their evaluation over time.
Age affects skin recovery time. Stopping moisturizer use in aging persons did not result in recovery after 3 weeks, in contrast to use in younger women. We hypothesize that older persons need longer time after stopping moisturizers to recover to their original skin condition. It is unclear if the small difference is noticeable for the participant with aging skin itself and therefore is rather a subjective finding, which could be a result of the nocebo effect. As far as all subjects from the older group were concerned, some were even convinced that by stopping the application of their moisturizer would cause their skin to wrinkle more; it is possible that their negative mindset resulted in a biased perception.
Older female subjects’ greatest fear at baseline was an increase in wrinkles, which is a widespread dread of older women [27]. Various studies support the rapid effectiveness of facial creams to reduce the appearance of fine lines and wrinkles [28, 29]. The majority of young participants concluded to stop using moisturizers after participation in our study, as they did not recognize any additional benefit for their facial skin. In contrast, all aging women restarted their moisturizer, which shows that its use is often influenced and shaped by subjective perception.
However, on the basis of current data, efficacy and disadvantages of moisturizing treatment depend on the complexity of formulations and the individual skin type [12, 19, 30]. A limitation of our study is the low number of participants with a short follow-up time. A larger cohort, a facial recognition and scanning technology, and a variety of laboratory and in vivo analyses would have provided more statistical power for more reliable conclusions. Another limiting factor for more personalized results was our present study’s lack of analysing different skin types. Furthermore, the study design did not allow blinding of subjects because of a conscious discontinuation of a previous treatment, which could have affected the subjects' self-assessments. Therefore, the results should be interpreted with caution. A follow-up study with a skin analysis imaging system based on artificial intelligence as an objective assessment tool and tape stripping to the evaluate skin barrier is planned.