Humectants, occlusives, and emollients – three classes of moisturizers. Which work, which are marketing.
562 ingredients in database · 455 with tier A/B evidence · 552 safe in pregnancy
Skin moisturisation works through three mechanisms. Humectants (glycerin, hyaluronic acid, sodium PCA, betaine, urea) pull water from the environment and from deeper skin layers into the stratum corneum. Occlusives (petrolatum, squalane, dimethicone, lanolin) form a film that slows transepidermal water loss (TEWL). Emollients (oils, fatty alcohols, ceramides, cholesterol) restore the intercellular lipid matrix between corneocytes.
The strongest effect comes from combining all three classes in one formula. That is the backbone of dermatological moisturisers for atopic skin and post-procedure recovery – CeraVe, Eucerin Aquaphor, La Roche-Posay Toleriane.
Hyaluronic acid is a cult ingredient, but it delivers only a surface, short-term effect. Low-molecular-weight HA (<50 kDa) penetrates deeper but at high concentrations can trigger inflammation. In dry climate or air-conditioned rooms, HA may actually pull water OUT of skin unless sealed with an occlusive on top.
Ceramides NP, AP, EOP make up about 50% of stratum corneum lipids. Their deficit is a key factor in atopic dermatitis. Clinical-grade moisturisers for atopic skin are built around a ceramide + cholesterol + fatty acid ratio of 3:1:1.
What works poorly: ethanol at high concentrations (>10% near the top of the ingredient list), surfactants in «moisturising» face washes, and mineral oil on already-damaged skin as the sole occlusive.
Sodium Hyaluronate
Sodium salt of hyaluronic acid. Structurally more stable than the acid itself and more common in formulations. Molecular weight determines behaviour: high-MW (> 1 MDa) holds water at the surface, low-MW (< 50 kDa) penetrates deeper. Cosmetics typically use a mix of MWs. A baseline moisturising active across all segments.
Hyaluronic Acid
Natural polysaccharide that binds water up to 1000 times its own weight. Topical application creates a surface humectant effect without dermal penetration.
Glycerin
The simplest trihydric alcohol and one of the most common humectants in cosmetics. Draws water from the environment and retains it in the stratum corneum.
Dimethicone
Silicone polymer that forms a protective film on the skin to lock in moisture. Gives products a silky texture and does not penetrate the dermis.
Colloidal Oatmeal
Finely ground oat flour with anti-inflammatory, moisturizing, and barrier properties. FDA-approved as an OTC skin protectant. Avenanthramides are the active anti-inflammatory compounds.
Urea
A natural moisturizing factor (NMF) present in the stratum corneum. Low concentrations moisturize; high concentrations act as a keratolytic. The gold standard for hyperkeratosis and xerosis.
Evigrade currently tracks 562 ingredients in the «moisturizing» category. Of those, 455 carry evidence tier A or B.
552 ingredients in this category are flagged as safe during pregnancy at typical cosmetic concentrations. Always confirm the choice with an OB-GYN.
550 ingredients in this category show both low irritation potential and low allergen risk, making them safe even for reactive and sensitised skin. A patch test is still advisable before first use.
Start with a single high-evidence ingredient (tier A or B) at a low concentration, 2–3 times per week. After 2–3 weeks without reaction, frequency can be increased. Do not introduce two new actives at once – if skin reacts, you won't know which one caused it.
Other categories
Sodium salt of hyaluronic acid. Structurally more stable than the acid itself and more common in formulations. Molecular weight determines behaviour: high-MW (> 1 MDa) holds water at the surface, low-MW (< 50 kDa) penetrates deeper. Cosmetics typically use a mix of MWs. A baseline moisturising active across all segments
Natural polysaccharide that binds water up to 1000 times its own weight. Topical application creates a surface humectant effect without dermal penetration
The simplest trihydric alcohol and one of the most common humectants in cosmetics. Draws water from the environment and retains it in the stratum corneum
Silicone polymer that forms a protective film on the skin to lock in moisture. Gives products a silky texture and does not penetrate the dermis
Finely ground oat flour with anti-inflammatory, moisturizing, and barrier properties. FDA-approved as an OTC skin protectant. Avenanthramides are the active anti-inflammatory compounds
A natural moisturizing factor (NMF) present in the stratum corneum. Low concentrations moisturize; high concentrations act as a keratolytic. The gold standard for hyperkeratosis and xerosis
Alcohol analogue of pantothenic acid. Penetrates skin and converts to pantothenic acid, required for coenzyme A synthesis. Accelerates healing and reduces irritation
A bioidentical ceramide from the non-hydroxylated class. One of the main lipids of the stratum corneum – restores the barrier and lowers TEWL. Pregnancy-safe
A fatty acid. It softens skin and supports product texture. Well tolerated
A multifunctional glycol. It hydrates and boosts preservative action. Well tolerated
A dipeptide of the amino acids alanine and glutamine. It supports skin hydration and comfort. Well tolerated
Non-essential amino acid. Part of the skin's natural moisturizing factor (NMF), humectant
Gel from aloe leaves containing polysaccharides, vitamins, and amino acids. Moisturizes, soothes irritated skin, and accelerates healing of minor injuries
A silk hydrolysate. It draws moisture, smooths skin and gives a soft silky finish. Well tolerated
A salt of lactic acid. It hydrates and gently exfoliates, softening rough, flaky skin, common in urea body products. At high levels it may slightly sting on broken skin
A peanut oil. It nourishes and softens skin and supports the barrier. Well tolerated; use caution with peanut allergy
A salt of the amino acid arginine. It supports hydration and joins a recovery complex. Well tolerated
A humectant from the amino acid arginine. It holds water in the skin and gently sets the formula pH. Well tolerated
An amino acid. It supports hydration and joins a recovery complex. Well tolerated
NMF amino acid – a component of the skin's natural moisturizing factor. Pregnancy-safe
A humectant and conditioner. It draws water and smooths the skin surface. Well tolerated
A derivative of the amino acid tyrosine. It works as a skin conditioner and a source of amino acids. Well tolerated
Hyaluronic acid with acetyl groups on the molecule. Acetylation adds lipophilicity, improves skin affinity and extends moisture retention versus the regular form
A waxy emollient and co-emulsifier. It thickens and gives creams smoothness and stability. Well tolerated
A fatty glycerin ether. It softens skin and supports cream texture without drying. Well tolerated
A waxy emollient ester. It softens, structures sticks and creams and gives a rich protective film. Well tolerated
A fatty-alcohol emollient and emulsifier. It softens skin and stabilizes the cream. Well tolerated
A long-chain fatty acid. It thickens cream and softens skin and supports texture. Well tolerated
Polysaccharide from yeast, fungal, or oat cell walls. An immunomodulator and humectant that stimulates macrophages and accelerates wound healing
Amino-acid humectant from sugar beet. Holds water in the stratum corneum, softens dryness and tightness, compatible with any formula
A biotech polysaccharide. It draws water and forms a soft moisturizing film on skin. Well tolerated
A rich emollient ester. It softens skin and gives a dense texture and shine. Well tolerated
An emollient close in structure to skin lipids. It restores softness and comfort, common in products for dry and sensitive skin. Well tolerated
A conditioning agent from rapeseed oil. It smooths skin and reduces static in hair. Well tolerated
Occlusive emollient made of purified hydrocarbons. Reduces transepidermal water loss by nearly 99% and restores the skin barrier after damage
A cranberry fruit water. It hydrates and tones skin, a source of antioxidants. Well tolerated
A plant wax from green tea leaves. It structures texture and softens skin. Well tolerated
A plant wax from sumac fruit. It structures sticks and balms and gives a soft pliable texture and a protective film. Well tolerated
A plant wax from rice bran. It thickens texture and forms a soft protective film. Well tolerated
A film-forming polysaccharide from larch. It forms a soft film on skin and helps hold moisture. Well tolerated
A light emollient ester. It softens, gives a dry slip and absorbs quickly without a greasy film. Well tolerated
A fatty alcohol emollient. It softens skin, stabilizes the emulsion and gives a smooth texture. Well tolerated
An emollient ester. It softens, gives a silky slip and a light protective film. Well tolerated
An emollient ester. It softens skin and gives a light slip without a greasy film. Well tolerated
A light plant emollient ester. It softens skin, absorbs fast and replaces volatile silicones. Well tolerated
Fragmented hyaluronic acid with a mass <50 kDa. Penetrates the epidermis better than the high-molecular form, but at high concentrations may trigger a pro-inflammatory response
A blend of coconut fatty acids. It thickens the formula and softens skin. Well tolerated
Hardened avocado oil. It nourishes and softens skin and gives the formula body. Well tolerated
A waxy emollient from jojoba oil. It softens, structures sticks and creams and gives a protective film. Well tolerated
A thickened olive oil. It softens skin and adds body to creams. Well tolerated
A hardened soybean oil. It softens skin and gives cream a dense texture. Well tolerated
An emollient and emulsifier from palm kernel oil. It softens skin and keeps the emulsion stable. Well tolerated
An emollient and emulsifier from palm fats. It softens skin, stabilizes the cream and gives a rich texture. Well tolerated
An emollient and antioxidant stabilizer. It softens skin and protects the oil phase from oxidation. Well tolerated
A plant emollient and antioxidant stabilizer. It softens skin and protects the formula from oxidation. Well tolerated
A waxy emollient ester from olive oil. It softens skin and gives the formula body. Well tolerated
A plant humectant from starch. It draws and holds water in skin and gives softness. Well tolerated
An emollient and emulsion stabilizer from palm fatty acids. It softens skin and keeps the cream firm. Well tolerated
A synthetic emollient polymer. It gives slip, a light film and lasting wear. Inert to skin
A light plant-derived emollient. It softens skin and gives a dry slip. Well tolerated
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