Moisturizers recommended, but product choice largely comes down to patient choice
For patients with atopic dermatitis, moisturizers may be the most important treatment. However, with impaired skin barrier functions, thinner stratum corneum cell layers, and larger follicular pores, atopic dermatitis patients are vulnerable to adverse skin reactions.
Selecting a moisturizer without sensitizing agents is a good start, but beyond that, the choice most often comes down to individual preference, wrote the authors of the 2014 American Academy of Dermatology treatment guidelines for atopic dermatitis topical therapies.
Moisturizers were described as the “cornerstone of therapy” in atopic dermatitis in the guidelines, but the products differ greatly by ingredients, which can improve the condition or make it worse. There is also considerable debate over which delivery systems work best — i.e., creams, ointments, oils, gels, or lotions.
Clinical trials comparing moisturizers in head-to-head trials are few and far between, and of the trials that have been conducted, the findings are inconsistent. In one study cited in the 2014 guidelines, of 39 people with mild to moderate atopic dermatitis, there was no difference in efficacy among patients who used hydrolipid cream with glycyrrhetinic acid; creams containing ceramides, cholesterol, and free fatty acids; or an over-the-counter petroleum-based skin protectant. Another study showed similar results for an over-the-counter oil-based moisturizing cream and a palmitoylethanolamide-containing prescription emollient device.
In the United Kingdom, the guidelines are more specific. For mild-moderate atopic dermatitis, occlusive emollient creams are recommended, depending on barrier thickness, lipid content variability, disease severity, and body site. For moderate to severe atopic dermatitis, occlusive emollient ointment is recommended. For severe atopic dermatitis, occlusive ointment with zero water content is advised.
In the Asian-Pacific region, consensus guidelines recommend regularly moisturizing, while taking into account humidity, climate, skin type, degree of dryness, disease duration and severity, age, treatment compliance, and adjuvant properties.
Moisturizers with Natural Ingredients
In a published review on the role of moisturizers with herbal and other natural ingredients for dermatitis, Schandra Purnamawati, MD, and colleagues at the Universitas Gadjah Mada in Indonesia, recommended moisturizers as a key treatment in atopic dermatitis, along with trigger avoidance and other therapeutic treatments.
Although few, clinical trials of moisturizers with natural oils show that some natural ingredients can lead to significant improvements in dermatosis, Purnamawati et al wrote. Among the most powerful of the ingredients are natural oils with a ratio of more linoleic acid (LA) than oleic acid (OA).
“High linoleic acid concentrations are believed to accelerate skin barrier repair and development, improving skin hydration, and ameliorate AD severity, making them perfect for steroid sparing,” the team wrote. “Safflower oil, sunflower seed oil, and sea buckthorn seed oil are natural oils with the highest LA/OA ratios.”
A recent study of Bangladesh pre-term infants showed that moisturizers with sunflower seed oil provided an “excellent barrier repair,” reducing the risk for developing nosocomial infections by 41%. In contrast, olive oil, which has a low LA/OA ratio, can significantly deteriorate the skin barrier.
Most skin conditions benefit from restoring skin ceramide levels, the authors noted. For atopic dermatitis, they recommended only moisturizers that contain natural or synthetic ceramides.
“According to Chamlin et al, topical mixtures of three key stratum corneum [SC] lipids consisting of ceramide, cholesterol, and free fatty acids in optimal proportions [3:1:1 molar ratio] can accelerate barrier repair following various external, acute, or sustained skin barrier disruption,” Purnamawati and colleagues continued. “Unlike non-physiologic lipid mixtures such as petrolatum, physiologic lipids (ceramides, cholesterol, and free fatty acids) can traverse both intact and disrupted SC.”
The review details the following about what is known to date about various herbal ingredients:
- Aloe vera: Newer moisturizers tend to contain anti-inflammatory ingredients, such as aloe vera, but these and other natural anti-inflammatories may not be suitable for patients with allergies; moisturizers with 0.1%, 0.25%, and 0.5% of aloe vera extract applied for 2 weeks can increase skin hydration without transepidermal water loss, a study cited in the review showed
- Bisabolol: A chamomile extract, bisabolol has been shown to produce significant improvements in pruritus and other symptoms associated with atopic dermatitis, and a randomized, double-blind clinical trial of 278 AD patients showed that when combined with heparin, α-bisabolol, applied twice daily for 8 weeks, “significantly” improved symptoms
- Shea butter: Derived from butyrospermum parkii kernels, shea butter consists mostly of stearic and oleic acids (85-90%), and also contains, albeit in small amounts, triterpene acetate and cinnamate esters, which can have anti-inflammatory and anti-tumor properties
- Glycyrrhetinic acid: A licorice root extract, glycyrrhetinic acid contains anti-inflammatory, antiviral, and anti-tumor effects, and contains additional properties that are beneficial in atopic dermatitis — licochalcone A, B, and D; a study involving children with mild to moderate atopic dermatitis showed that a moisturizer containing licochalcone and applied twice daily improved symptoms over atopic dermatitis patients treated with hydrocortisone lotion
- Niacinamide: The vitamin niacinamide was shown to improve skin barrier functions by increasing epidermal ceramides and other intercellular lipids levels by promoting serine palmitoyltransferase upregulation; applied twice daily, moisturizers with niacinamide were shown to decrease transepidermal water loss, reduce inflammation, and increase stratum corneum thickness
- Palmitoylethanolamide: The endogenous lipid palmitoylethanolamide derives from the fatty acid N-acylethanolamine, and resembles stratum corneum components and functions as peroxisome proliferators activated receptor α agonist; moisturizers with this ingredient contain both anti-inflammatory and analgesic properties, and a clinical trial of 2,456 patients with severe atopic dermatitis who were taking topical corticosteroids showed that these moisturizers improved pruritus, dryness, and eczema
- Zinc gluconate: A zinc salt, zinc gluconate, from gluconic acid, has been shown to reduce skin inflammation, with recent evidence showing that its anti-inflammatory effect may target peroxisome proliferator-activated receptors-α, human β-defensin-2, and the calcium-binding protein psoriasin, the review noted
- Combination ingredients: In addition, a combination of glycyrrhetinic acid (from the herb liquorice), Vitis vinifera (grape seed extract), and telmesteine in combination with shea butter (emollient) and hyaluronic acid (humectant), make up the product MAS063DP (Atopiclair); this was the first product approved by the U.S. Food and Drug Administration for allergic contact dermatitis, with some studies suggesting it can be used as monotherapy for both pediatric and adult mild-to-moderate atopic dermatitis