The "Ceramide Deficiency" Cause of Atopic Dermatitis Demonstrated, and 7 Curel Picks from the Drugstore

This article first sets out what these research findings mean, then covers seven skincare products from Kao's Curel line, which uses the company's pseudo-ceramide technology. The seven were chosen with attention to ingredient composition and irritation potential.

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In this study, the researchers created transgenic mice that overexpress acid ceramidase, a ceramide-degrading enzyme, in the epidermis. From an early age, the mice showed severe dryness and scaling, a marked decline in barrier function, reduced water retention and a substantial drop in stratum corneum ceramides. When dust mite antigen was administered, they showed increased Th2-type inflammation closely resembling atopic dermatitis. Normal mice showed almost none of this response. The results indicate that ceramide loss is not merely a consequence of inflammation. Ceramide deficiency itself can cause barrier breakdown and nerve hypersensitivity, and may directly trigger allergic inflammation.

However, these findings are at the press-release stage and come from basic research in mice, so they have not yet become established doctrine in human clinical practice. Even so, they come from a researcher with an established track record in dermatology. There are hopes that the medical value of ceramide replacement therapy will eventually be recognized, which could lead to pharmaceutical applications and, through an expanded raw-material supply, cheaper cosmetics.

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Among drugstore cleansers, this stands out as a product with an exceptionally gentle cleansing formula.

• Key ingredients: Dipotassium glycyrrhizinate (an anti-inflammatory) as the active ingredient, with sodium lauroyl aspartate solution as the base cleansing agent.
• Features: Built around a mildly acidic, amino acid-based cleanser, it is formulated to remove sebum and dirt moderately while preventing excessive loss of ceramides from the stratum corneum. It poses a lower risk of ceramide loss during washing than typical alkaline soaps.
• Points to note: The product itself contains no pseudo-ceramide. The speaker's analysis is that ceramides added to a cleanser would simply be rinsed away, so the product deliberately leaves them out, keeping costs down and the formula simple. It costs ¥1,760 (tax included) for 150 ml and dispenses ready-made foam, so no lathering is needed.

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This lotion targets dandruff and itching caused by a dry scalp, and its formulation is unusual within the Curel lineup.

• Key ingredients: Classified as a cosmetic, with no active (anti-inflammatory) ingredient. It has a base of BG, betaine and glycerin, and contains a pseudo-ceramide (cetyl-PG hydroxyethyl palmitamide) and eucalyptus extract.
• Features: Most Curel skincare products contain an anti-inflammatory ingredient such as dipotassium glycyrrhizinate, and layering several items can raise concerns about overlapping ingredients. This product contains no anti-inflammatory ingredient and aims solely at moisturizing with pseudo-ceramide.
• Feel: It avoids the heavy stickiness of glycerin-based formulas, with BG and betaine giving it a light, refreshing feel. It contains no cooling or irritating ingredients such as menthol or ethanol, and its rounded direct-application nozzle makes it easy to apply straight to the scalp. ¥1,430 (tax included) for 120 ml.

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This booster serum packs high-concentration carbonation (carbon dioxide) into fine foam.

• Key ingredients: Dipotassium glycyrrhizinate as the active ingredient. Contains high-concentration carbon dioxide and a pseudo-ceramide (hexadecyloxy PG hydroxyethyl hexadecanamide).
• Mechanism: When the foam is left on the skin, the carbon dioxide is absorbed transdermally and temporarily boosts local blood flow. This can help with dullness and dark circles caused by poor circulation. It also softens the stratum corneum, acting as a booster that helps subsequent skincare penetrate.
• Positioning: It builds on the carbonation technology developed for Kao's Sofina iP, reformulated to be gentler for sensitive skin and with pseudo-ceramide added. At ¥3,850 (tax included) for 120 g, it is priced to be more accessible than existing carbonated serums.

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This serum, formulated with a new active ingredient, is aimed at sensitive skin that experiences hypersensitivity or a tingling sensation.

• Key ingredients: Gamma-amino-beta-hydroxybutyric acid (GABOB) as the active ingredient. Also contains pseudo-ceramide and a sphingosine derivative, among others.
• Mechanism: The proposed mechanism is that it promotes the formation of tight junctions in the granular layer of the epidermis, calming the hypersensitivity of sensory nerves that had grown excessively in response to external stimuli. The ingredient had been used in Kao's prestige brand Twany and elsewhere, and this marks its first use in a product sold through drugstores.
• Feel: It comes in a dropper bottle and has a fresh, light texture, unlike the rich textures common in other Curel products. It is well suited to supporting the barrier of skin that tingles at the slightest irritation, such as during pollen season. ¥4,950 (tax included) for 30 ml.

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This line combines brightening care with ceramide replenishment, and you can choose between the milk and the cream depending on your goals and preferred feel.

• Active ingredient: Chamomilla ET (a brightening active derived from chamomile).
• Features: Chamomilla ET is Kao's proprietary brightening ingredient and is usually found mainly in department-store cosmetic lines, but this product offers outstanding value at ¥2,530 (tax included) for 110 ml. It also contains pseudo-ceramide and has a light feel, making it suitable for brightening and moisturizing large areas.

• Features: A soufflé-textured cream with a high concentration of pseudo-ceramide. The standard Intensive Moisture Care Face Cream (active ingredient: allantoin) is said to contain about 8% pseudo-ceramide, whereas this product uses the brightening active Chamomilla ET.
• How to choose: If you already use an anti-inflammatory ingredient such as dipotassium glycyrrhizinate in other skincare products, this cream lets you avoid doubling up on anti-inflammatories while adding a brightening ingredient and sealing everything in with high-concentration pseudo-ceramide. ¥3,080 (tax included) for 40 g. Choose the cream if you want a higher pseudo-ceramide concentration, or the milk if you prioritize value for Chamomilla ET.

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A tinted lip balm for people prone to dry or chapped lips.

• Features: It contains none of the tar dyes, dyes or cochineal commonly used in colored lip products and lipsticks, and is based mainly on low-irritation mineral oil, petrolatum and ceresin. It also contains no anti-inflammatory active ingredient.
• Feel and color: Available in four shades: pink, bordeaux, red and beige. The tint is not strong; it gives an extremely natural color that only enhances the lips' natural flush, so men can wear it without it looking out of place.
• Points to note: From personal experience, the speaker has been able to use the pink shade continuously without irritation, but has had itching with some of the other shades. Be aware that individual reactions may vary depending on the combination of pigments. The price is ¥1,045 (tax included).

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This lineup, spanning cleanser, booster serum, high-performance serum, milk and cream, and lip care, is organized to minimize overlapping anti-inflammatory ingredients while efficiently supplying the skin with pseudo-ceramide.

Now that research has shown that ceramide deficiency may directly trigger barrier breakdown in atopic dermatitis and chronically sensitive skin, protecting and replenishing stratum corneum ceramides through daily skincare is highly worthwhile. Beyond expensive products containing human-identical ceramides, appropriately combining affordable pseudo-ceramide products is an effective way to keep your skin stable day to day.