1. Division of Dermatology, University of Toronto, Toronto, ON, Canada
2. Faculty of Medicine, University of Toronto, Toronto, ON, Canada
3. University Health Network (Western Division), Toronto, ON, Canada
Atopic dermatitis (AD) or eczema is a chronic, relapsing form of skin inflammation that is attributable to multiple pathogenic, genetic, and environmental factors, as well as a dysfunctional epidermal barrier. Immune responses involved in AD culminate in dry skin, pruritus, and IgE mediated sensitization to food and environmental allergens.1 An improved understanding of crucial skin barrier defenses and the inflammatory cascade that drives disease activities has led clinicians to reassess conventional approaches to treatment and recognize emollients for their therapeutic potential. Accordingly, emollient-based moisturizers and cleansers have been established as essential adjuvants for successful AD management.
AD is very common.
- Prevalence is estimated at 15%-30% in children and 2%-10% in adults.2
- In 85% of AD-afflicted children, onset of disease occurs before the age of 5 years.3
- Up to 70% of children experience a spontaneous remission before adolescence.4
AD is associated with a marked decrease in skin barrier function due to endogenou factors.
- Increasing evidence implicates one of the primary causes of AD as a genetic defect in the epidermis that permits the infiltration of allergens, environmental irritants, and microbes, thus inducing inflammatory responses.5
- A defective skin barrier prohibits the necessary levels of antimicrobial peptides to form in the epidermis in order to protect against infectious agents, such as Staphylococcus aureus (S. aureus).
The Role of Moisturizers in Optimal AD Management
A persistent feature of AD is dry skin that is caused by a combination of intrinsic disease mechanisms and hyperreactivity to exogenous factors. Some treatments for AD can further exacerbate xerosis, itching, and irritation. Such external insults on an already impaired skin barrier drive the dry skin cycle and leave skin vulnerable to microbial infections. For these reasons, maintaining hydration and restoring epidermal barrier defenses provide the rationale for moisturization therapy.
What are Moisturizers?
- Moisturizers are composed of a combination of key ingredients that are categorized as emollients, humectants, and occlusives, which work synergistically to enhance hydration and barrier function.
- A randomized controlled study showed that well-designed formulations incorporating these constituents can improve the epidermal barrier function and increase skin hydration levels; however, the effects are determined by individual product composition.6,7
How do Moisturizers Work?
- The mechanism of action of emollients may be elucidated as a role substitution by lipid ingredients, which take on the functions of naturally occurring lipids that are either absent or impaired in eczematous skin.
- Treatment of the skin with moisturizers can repair the skin barrier, increase water content, reduce transepidermal water loss (TEWL), and restore the lipid barriers’ ability to attract, retain, and redistribute water.
- Maximum effects are derived from prophylactic and frequent use.
- Moisturizers maintain hydration in the skin by slowing TEWL. In doing so, they help dry and/or aging skin to improve its structural integrity, appearance, and tactile properties.
- By covering tiny fissures in the skin and providing an occlusive protective film over the stratum corneum (SC), moisturizers restore the epidermal barrier and reduce the penetrability of allergens and irritants.
Moisturizers Demonstrate Adjuvant Properties
- Regimented moisturization has become standard adjunctive AD therapy by serving as a foundation to support pharmacologic measures, reducing the need for topical corticosteroids and calcineurin inhibitors, and mitigating the side-effects from medications.
- During flares, OTC combination preparations containing a moisturizer with a topical corticosteroid (e.g., clobetasone and hydrocortisone) are helpful to control inflammation and restore the skin barrier.
Essential Components of Effective Moisturizers
- Emollients are mainly lipids and oils that hydrate and improve the appearance of the skin by contributing to softness, smoothness, and improved flexibility (Table 1).
- The lubricity of some moisturizers can influence consumer satisfaction and product preference.
- The SC of AD patients have significantly reduced levels of ceramides (lipid molecules), which are important components of skin structure.
- The topical replacement of lipids serves to ‘fill the cracks’ between clusters of desquamating corneocytes.
- Humectants attract and retain hydration in the skin by enhancing water absorption from the dermis into the epidermis, or by absorbing water from the external environment (Table 2).
- Many humectants also have emollient-like properties.7
- The most effective humectant is the trihydroxylated molecule, glycerin, which is also commonly referred to as glycerol.
- Glycerin is the most widely used humectant.
- A double-blind study comparing glycerin with urea showed that although both compounds were equally effective in treating xerosis, glycerin caused significantly less adverse skin reactions.8
- Urea is another commonly used humectant that is effective against TEWL.
- Avoid the use of urea-containing moisturizers in young children due to irritation.
- Occlusives reduce TEWL by creating a hydrophobic barrier over the skin and contributing to the matrix between corneocytes (Table 3).
- Efficacy is enhanced when occlusives are applied to slightly dampened skin.
- Their main limitations include odour, potential allergenicity, and a ‘greasy’ feel.
- Petroleum jelly (petrolatum), in a minimum concentration of 5%, is the most effective occlusive, followed by lanolin, mineral oil, and silicones.
- Silicone-based derivatives (e.g., dimethicone) are oil-free alternatives that are noncomedogenic, nonirritating, nonsensitizing, and more cosmetically acceptable.
Recommendations for Use
The following adapted guidelines for the use of moisturizers in AD, developed by the National Institute for Health and Clinical Excellence,9 serve as practical advice for patients and their doctors.
- Physicians should be prepared to offer patients a choice of unperfumed emollients:
- suited to their individual needs and preferences.
- for everyday moisturizing, as well as emollient-enriched washing and bathing formulations.
- Moisturizers should be:
- used more often and in larger amounts than other treatments.
- used even when AD is clear.
- used while using other treatments.
- offered as a single or combination product (offer alternatives if one formulation causes irritation or does not gain patient acceptance).
- easy to apply throughout the day.
- Recommend leave-on moisturizers in large quantities.
- Instruct patients or their parents on sufficient and proper application.
- When multiple topical products are used concurrently, instruct patients to apply them one at a time, allowing for several minutes to pass in-between applications.
- Consider increasing the use of emollients if patients report difficulties in controlling itch.
Mild Skin Cleansers
The regular use of mild cleansers is an important aspect of optimal AD management. Not only is cleansing an essential part of basic hygiene, but it also removes dirt, sweat, bacteria, and exfoliated cells, which prepares the skin to receive topical medications and improves drug absorption.
- AD lesions are commonly colonized with S. aureus. Routine cleansing can enhance antimicrobial activity against S. aureus and decrease the chances of infection.
- Care must be taken to minimize any further weakening of the SC barrier during cleansing. The use of improper techniques and unsuitable cleansing agents on the face or body can initiate flares or exacerbate AD.
- The use of anionic detergents (i.e., soaps) can alter the pH of skin, resulting in increased sensitivity to irritants and conditions that can promote bacterial proliferation.10
- While removing excess sebum, cleansers can also inadvertently damage intercellular lipids, which can lead to further impairment of the barrier function and cause dry skin.
- Cleansers that are suitable for eczematous skin are generally based on mild synthetic surfactants that cause minimal barrier disturbances.
- Non-ionic surface-acting agents (e.g., silicone and polysorbate) are less likely to cause irritation and are pH-compatible with the skin.
- Silicone surfactants, such as dimethicone, are effective at eliminating surface debris without completely stripping away protective oils.
- Emollients contained in cleansers can minimize barrier damage by emulsifying dirt and oil for easy removal, while at the same time replacing lipids that are lost during the washing process.11
Using the 4 Rs of AD Management
The best practice management of AD must include patient education. Pharmacists are encouraged to provide verbal and written information on AD and selected treatments, as well as practical demonstrations of proper administration. Remembering the 4 Rs can help to simplify the multi-layered approach for management.
- Recognize and diagnose the condition promptly in order for treatment to be initiated.
- AD patients have a predisposition for developing other atopic conditions, such as asthma and allergic rhinitis.1
- Encourage patients to maintain a diary to track foods eaten, flares, and the use of medications, moisturizers, and cleansers, which can guide therapeutic decision-making.
- Avoidance is a central AD management strategy. Identify and eliminate relevant triggers (e.g., irritants, aeroallergens, and foods) and seek ways to reduce stress.
- Mild cleanser use can help to remove surface dirt, irritants, and microbes.
- Consider allergy testing to identify triggers.
- The regimented use of emollients can partially repair and restore the skin barrier and reduce infections and allergic reactivity.
- Body washes incorporating nonirritating surfactants, emollients, and humectants can replenish barrier lipids during cleansing to minimize TEWL. Lukewarm baths (5-10 minutes in duration) are recommended over showers.
- Creams and ointments are more effective for eczematous skin. Apply moisturizers 3-5 minutes after bathing.
- When flares occur, interrupt and regulate inflammatory responses with immediate treatment in order to break the itch-scratch cycle and limit AD severity.
- Therapeutic strategies include topical corticosteroids, topical calcineurin inhibitors, antimicrobials, and oral antihistamines, as well as routine skin care.
- In patients exhibiting an inadequate response to therapy, assess treatment adherence, side-effects, and review moisturizer and cleanser use.
Due to the chronicity of AD, as well as multiple factors contributing to its etiology, successful management requires a multipronged approach that includes lifestyle modifications, adaptations to skin care practices, and medical intervention. Although topical corticosteroids are firmly established as the cornerstone therapy, long-term and overuse are associated with skin atrophy and adverse systemic effects. The combination of moisturizers with topical steroids can have a significant steroid-sparing effect, especially in children with mild-to-moderate AD. A therapeutic approach that incorporates patient education and emollient therapy can complement pharmacologic measures to extend periods of remission and significantly lessen the disease burden.
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- Williams H, et al. J Allergy Clin Immunol 118(1):209-13 (2006 Jul).
- Beltrani VS, et al. Dermatol Online J 9(2):1 (2003 Mar).
- Illi S, et al. J Allergy Clin Immunol 113(5):925-31 (2004 May).
- Kisich KO, et al. J Allergy Clin Immunol 122(1):62-8 (2008 Jul).
- Buraczewska I, et al. Br J Dermatol 156(3):492-8 (2007 Mar).
- Del RossJQ. Cosmeceutical moisturizers. In: Draelos ZD, ed. Procedures in cosmetic dermatology series: cosmeceuticals. 1st ed. Philadelphia: Elsevier p97-102 (2005).
- Loden M, et al. Acta Derm Venereol 82(1):45-7 (2002).
- National Institute for Health and Clinical Excellence. Atopic eczema in children (2007 Dec).
- Draelos ZD. Dermatol Clin 18(4):597-607 (2000 Oct).
- Cork MJ. J Dermatolog Treat 8(Suppl 1):S7-13 (1997).