Sara Mirali, PhD1; Patrick Fleming, MD, MSc, FRCPC, FCDA1,2,3; Charles W. Lynde, MD, FRCPC, DABD1,2,3
1Department of Medicine, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
2Division of Dermatology, Department of Medicine, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
3Lynde Institute for Dermatology, Markham, ON, Canada
Conflict of interest:
Funding sources: None. Conflicts of interest: Sara Mirali has no conflicts of interest to declare. Patrick Fleming has received honorarium and/or consulting and/or advisory boards and/or speaking fees for AbbVie, Altius, Amgen, Aralez, Bausch Health, Cipher, Galderma, Eli Lilly, L’Oréal, UCB, Janssen, Novartis, Pfizer, and Sanofi-Genzyme. Charles Lynde has acted as a principal investigator, speaker and/or consultant and/or advisory board member for AbbVie, Amgen, AnaptysBio, Avillon, Arcutis, Bristol-Myers Squibb, Celgene, Cipher, Genentech, GlenMark, Incyte, Janssen, Leo Pharma, L’Oréal, Kyowa, Pfizer, Merck, Novartis, and Sanofi.
Abstract:
During the COVID-19 pandemic, prolonged usage of personal protective equipment (PPE) and frequent handwashing has exacerbated or caused skin diseases, particularly amongst frontline workers. Skin conditions, such as atopic dermatitis, irritant contact dermatitis, and hand eczema, affect patients’ quality of life and their ability to work. These conditions can be managed by frequent moisturization and washing with gentle cleansers. In this review, we discuss the properties of effective moisturizers and cleansers for patients with skin diseases related to enhanced infection control procedures.
Key Words:
COVID-19, personal protective equipment, PPE, skin pH, eczema, atopic dermatitis, irritant contact dermatitis, acne, hand eczema
Table of Content:
Introduction
During the COVID-19 pandemic caused by the novel coronavirus SARS-CoV2, health authorities advised frontline workers and the public to take infection control precautions. Current evidence suggests that COVID-19 is transmitted through respiratory droplets and contact with contaminated surfaces.1 To prevent transmission, frequent handwashing and prolonged usage of personal protective equipment (PPE), such as goggles, masks, face shields, and gloves, are recommended. These enhanced precautions can cause or exacerbate inflammatory skin conditions, which impact patients’ quality of life and, in some cases, their ability to work.2 Moreover, associated symptoms, such as pruritis affecting the face, increase the risk of transmission.
Recent studies have shown that 75-97% of healthcare workers (HCWs) treating COVID-19 patients suffered from adverse skin reactions, including contact and pressure urticaria, rosacea, perioral dermatitis, contact dermatitis, or aggravation of preexisting skin disorders. The most commonly affected areas were the hands, cheeks, and nasal bridge.2,3 These adverse effects are not restricted to HCWs4 and are mainly caused by the hyperhydration effects of PPE, friction, epidermal barrier breakdown, and contact reactions. All of these can aggravate preexisting skin diseases or cause new skin diseases, many of which can be controlled with proper moisturization. In this review, we discuss the role of moisturizers and cleansers in the management of skin conditions caused by frequent handwashing and PPE.
PPE-related Dermatitis
Atopic dermatitis (AD) and irritant contact dermatitis (ICD) are common types of eczema that are characterized by pruritus, eczematous lesions, xerosis, and lichenification. AD is a chronic relapsing inflammatory skin condition that often develops at a young age, while ICD is caused by direct contact of the skin with environmental, chemical, or physical agents that disrupt the epidermal barrier.5,6 AD and ICD can be exacerbated or caused by wearing PPE for long periods of time.2,3
Prolonged usage of PPE can also exacerbate or cause acne vulgaris.7,8 The tight seal and humid environment created by masks, particularly N95s, aggravates acne (also known colloquially as maskne). This is likely because pressure on the skin can rupture comedones and block pilosebaceous ducts. Moreover, the humid microclimate within the mask is ideal for bacterial growth and prevents filaggrin (FLG) breakdown, which contributes to skin barrier disruption.8,9 In addition to AD and acne, masks can exacerbate other inflammatory skin disorders, such as rosacea and perioral dermatitis.7,8
Moisturizers
Moisturizers are widely used to treat AD and ICD. Moisturizers treat damaged skin by repairing the stratum corneum, increasing hydration, and reducing transepidermal water loss (TEWL). In addition to restoring the skin barrier and relieving symptoms, frequent use of moisturizers can reduce the need for topical steroids.10 While steroids may reduce inflammation, they can also compromise the skin barrier and increase TEWL.11
An effective moisturizer should contain an occlusive barrier, humectants, and emollients (Table 1). Occlusives block TEWL by forming a film on the surface of the skin, while humectants retain moisture by attracting water from the environment and from the dermis. Emollients soften the skin by repairing the stratum corneum’s lipid-rich matrix and filling the spaces between desquamating corneocytes.
Property | Purpose | Side Effects | Examples |
Occlusive barrier | Creates a protective barrier and reduces TEWL | Cosmetically unappealing, occlusive folliculitis (petrolatum, mineral oil), contact dermatitis (lanolin) |
|
Humectants | Attracts water from external environment and dermis | Irritation (lactic acid, PCA, urea) |
|
Emollients | Smooths skin, restores stratum corneum’s lipid-rich matrix | Sometimes ineffective |
|
Table 1: Basic properties of an effective moisturizer
PCA = pyrrolidine carboxylic acid; TEWL = transepidermal water loss
Treatment with moisturizers is largely based on patient compliance. Consumer preferences must be taken into account as compliance will likely be poor if patients are unsatisfied with the treatment.12 An ideal moisturizer should be non-irritating, hydrating, cosmetically appealing, pH balanced, and contain ceramides.10,13,14 Moreover, an ideal moisturizer should be inexpensive and widely available.
Non-irritating
Sensory reactions are a common adverse effect of moisturizers. Sensory reactions consist of burning or stinging sensations without evidence of inflammation.15 Although urea, lactic acid, and pyrrolidine carboxylic acid (PCA) are clinically effective humectants, they cause irritation in some patients, particularly in those with damaged skin.12,16,17 In contrast, the humectant glycerin is well-tolerated.16 Preservatives, such as benzoic acid and sorbic acid, can also cause irritation (Table 2).12,17
Adverse Side Effect | Potential Causes |
Acne vulgaris | petrolatum |
Allergic contact dermatitis | lanolin, fragrances, preservatives (benzoic acid, sorbic acid), MCI/MI, vitamin E, chamomile oil, aloe vera, olive oil, tea tree oil |
Contact urticaria | preservatives, fragrances |
Irritation | humectants (lactic acid, PCA, urea), preservatives, propylene glycol, solvents, retinoids, benzoyl peroxide |
Occlusive folliculitis | petrolatum, mineral oils |
Photosensitivity or photomelanosis | fragrances, alpha hydroxy acids, sunscreens |
Table 2: Side effects of moisturizers and potential causes
Adapted from Lynde et al.23
PCA = pyrrolidine carboxylic acid
MCI/MI = methylchloroisothiazolinone/methylisothiazolinone
Fragrances are the most common allergen found in moisturizers and are the most frequent cosmetic cause of allergic contact dermatitis.18,19 Fragrances can also cause photo contact dermatitis and contact urticaria.20 Moisturizers should be fragrance-free and fragrance-related allergens, such as benzyl alcohols, essential oils, and biologic additives should also be avoided.18 dermatitis and contact urticaria.20 Moisturizers should be fragrance-free and fragrance-related allergens, such as benzyl alcohols, essential oils, and biologic additives should also be avoided.18
Moisturizers may contain or be used alongside treatments for acne vulgaris, such as retinoids and benzoyl peroxide. These compounds can disrupt the skin barrier and cause further irritation, particularly if patients recently integrated them into their skincare routine.21 To prevent maskne, skincare routines should be limited to a pH-balanced gentle non-soap cleanser and mild moisturizer free of irritants. Products with a physiological skin surface pH (4.0-6.0) should be used to reduce inflammation and improve skin barrier function.22 Changes in skincare routine (i.e., addition of a retinol) should be incorporated with caution because mask occlusion may worsen irritation from new products. Likewise, cosmetic products should not be used as mask occlusion will intensify product delivery to the skin, increasing irritation and maskne.
Hydrating Properties
Moisturizers derive their hydrating properties from humectants that attract water from the dermis and from the external environment. Within the stratum corneum, corneocytes contain natural moisturizing factors (NMF), a humectant mixture derived from amino acids and salts. NMF are made of amino acids produced by the breakdown of the protein FLG, which retains water within the corneocytes and maintains skin hydration.24 Patients suffering from AD are deficient in FLG, resulting in increased TEWL and impaired skin barrier function.25 Moisturizers containing FLG breakdown products have been shown to improve barrier function in AD patients.26
Commonly used humectants include the FLG breakdown products lactic acid and PCA, as well as urea. Another frequently used humectant is hyaluronic acid, which has been shown to be efficacious in mild-to-moderate AD.27 If patients are sensitive to these humectants, a moisturizer with glycerin should be considered. Glycerin is an effective humectant that is inexpensive and well-tolerated.16 Because humectants draw up water from the dermis, they must be used in combination with an occlusive agent to prevent TEWL.28
Cosmetically Appealing
Moisturizers are formulated to be non-greasy, non-comedogenic, and smoothing. The consistency of a moisturizer depends on its emulsification. Creams are available as water-in-oil (W/O) or oil-in-water (O/W) emulsions. O/W emulsions are less viscous compared to W/O emulsions, which have an oil content between 15-30%. A higher oil content retains more moisture but increases the greasiness of the product.15
New emulsion technologies allow for better delivery of active ingredients. Multivesicular emulsions (MVE®) are multi-lamellar emulsions with a series of concentric spheres containing oil and water. Ingredients are stored within the oil or water phases and layers are released slowly over time. While traditional emulsions release all of their ingredients at once, MVEs® allows for sustained release, increasing the effective duration of the product.29
pH Balanced
Normal physiological skin surface pH ranges from 4.0-6.0 but is elevated in AD, ICD, and acne.30-32 Elevated skin pH can result in inflammation, disrupted stratum corneum cohesion, and impaired skin permeability. Moreover, for individuals with acne-prone skin, high pH moisturizers can interfere with the efficacy of topical acne treatments.22,33 To improve skin barrier function, moisturizers at physiological skin surface pH (4.0-6.0) should be used, although there is limited clinical evidence directly linking low pH moisturizers and reduced irritation.
Ceramide Content
The stratum corneum’s lipid-rich matrix is composed of approximately 50% ceramides, 25% cholesterol, and 10-20% fatty acids.34 Ceramides are synthesized in keratinocytes and play an important role in skin barrier maintenance, cell adhesion, and epidermal differentiation. Reductions in ceramide correlate with clinical irritation and barrier disruption.35 Natural ceramides are expensive to synthesize but moisturizers containing synthetic ceramides have been shown to reduce symptoms and improve quality of life in patients with AD and ICD.10,13,14,36
Hand Eczema
Hand eczema (HE) is the most common form of ICD.37 Anionic surfactants, commonly found in hand soaps, disrupt the stratum corneum by damaging proteins and the processing of new lipids, allowing for greater penetration of irritants and TEWL.38 Likewise, extended exposure to water disrupts the stratum corneum’s lipid structure and increases skin permeability.39 Other irritants, such as organic solvents used in hand sanitizers, strip away lipids from the stratum corneum, although they are less damaging compared to harsh detergents.40
Cleansers
Cleansers are mainly available as soaps, combars, and synthetic detergents (syndets) (Table 3 & Table 4). Soaps are typically very alkaline and range from pH 9.0-10.0. In contrast, syndets contain synthetic detergents and are acidic or neutral (pH 5.5- 7.0). Combars are a combination of soaps and syndets.41 While soaps are more effective at removing soluble proteins and lipids, their high pH disrupts the skin barrier and causes irritation.42 Fragrance-free, hypoallergenic, non-soap cleansers that are neutral to low pH are recommended.43 Frequent handwashing with low pH cleansers is preferred as they have been shown to be less irritating.44
Cleanser | Description | pH Range | Surfactants |
Soap |
| 9.0-10.0 |
|
Combars |
| 7.0 | Combination of soap and syndet detergents |
Synthetic detergents (syndet) |
| 5.5-7.0 |
|
Table 3: Cleanser categories
Allergen | Examples |
Fragrance | Any fragrance or fragrance-related components |
Surfactants |
|
Preservatives |
|
Table 4: Allergens in cleansers
Adapted from Rundle et al.40
Conclusion
Prolonged PPE usage and frequent handwashing increases the risk of developing or aggravating skin diseases, such as AD, ICD, acne, and HE. Routine moisturization with non-irritating, pH-adjusted, ceramide-based products and gentle cleansing with a pH-adjusted cleanser can treat the unique dermatological challenges posed by COVID-19 (Table 5).
Characteristic | Recommendation | Clinical Evidence |
Non-irritating |
| In a double-blind, randomized study of 197 AD patients, 20% cream caused less adverse effects compared to a cream containing 4% urea and 4% sodium chloride.16 In a multi-centre, randomized trial of 3119 individuals, the prevalence of fragrance contact allergies was found to be 0.7-2.6%.45 |
Hydrating | Use moisturizers with FLG breakdown products or other humectants | In a single-centre intra-individual comparison trial of 20 AD patients, a moisturizer containing FLG breakdown products and ceramide precursors reduced TEWL and improved clinical symptoms.26 |
Cosmetically appealing | Avoid moisturizers that contain petrolatum | Petrolatum is cosmetically unappealing to some patients.43,46 |
pH balanced | Moisturizers and cleansers with a pH of 4.0-6.0 should be used | Subjects using low pH soaps reported less irritation compared to those using high pH soaps.44 |
Contains ceramides | Moisturizers that contain ceramides improve symptoms of eczema and xerosis | In a cohort study of 151 pediatric and adult AD patients, twice-daily use of CeraVe® improved quality of life and skin condition after 6 weeks.13 Compared to a standard hydrophilic cream, CeraVe® improved barrier function and decreased TEWL and skin pH in 24 senior xerosis patients.14 In a single-centre, randomized study of 60 patients with mild to moderate eczema, use of CeraVe® moisturizer and cleanser twice daily with fluocinonide cream 0.05% significantly improved outcomes after 4 weeks.10 |
Table 5: Ideal characteristics of moisturizers/cleansers and summary of recommendations
AD = atopic dermatitis; FLG = filaggrin; PCA = pyrrolidine carboxylic acid; TEWL = transepidermal water loss
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