Hydration Multiplier Hyaluronic Acid Serum

The base most products are built on. It carries the other ingredients and has no safety concern.

Pentylene glycol is a humectant and solvent that also offers mild antimicrobial support in formulas. It is generally well tolerated, with only rare reports of irritation, mostly in already sensitive or compromised skin.

A corn-derived solvent and humectant that has largely replaced propylene glycol in "clean" formulas; CIR reviewed the alkane diol group and found use concentrations up to about 40 percent in leave-on products like deodorant sticks with no meaningful irritation signal.

A lightweight, odorless emollient made by combining coconut or palm-derived fatty acids with glycerin. It spreads easily, feels non-greasy, and has a long history of use in skin and hair products with no meaningful irritation or sensitization signal.

A stable, saturated version of squalene, a lipid the skin already produces, now usually sourced from olives or sugarcane instead of shark liver. It is very well tolerated across skin types and helps reinforce the skin barrier.

A long-chain fatty alcohol used to thicken and stabilize creams and soften skin. It is a waxy emollient, not a drying solvent, and is graded low concern in published assessments.

A five-carbon alcohol used as a humectant to draw moisture into the skin and help formulations remain stable. It is well tolerated in the concentrations used in cosmetics.

A multi-ester emollient created from pentaerythritol and ethylhexanoic acid. It provides silky texture and skin conditioning with no documented safety concerns at cosmetic concentrations.

A naturally derived humectant made from fermented plant sugars that draws water into the skin. It is well tolerated in cosmetics and is used to support hydration and skin softness.

An emulsifier made from glycerin and stearic acid that stabilizes oil-in-water and water-in-oil formulations. It has a long history of safe use in cosmetics and is assessed as a low-concern ingredient in published safety reviews.

A humectant that draws water into the skin. One of the best-studied, best-tolerated ingredients in personal care.

A light coconut-derived emollient ester used as a natural-feeling alternative to silicones, giving a dry, velvety finish. It is well tolerated and graded low concern in published assessments.

A crosslinked acrylic polymer that thickens and stabilizes formulations. Published assessments show it to be well tolerated at cosmetic use levels, with no evidence of penetration into viable skin layers or systemic absorption.

One of the three major ceramides naturally found in human skin. Ceramide AP plays a critical role in maintaining the skin barrier and is extensively studied as a safe, essential ingredient. It is derived synthetically or from plant sources.

An amino acid polymer derived from glutamic acid that functions as a humectant to draw moisture into skin. It is graded with no known concerns in cosmetic use and is well tolerated across skin types.

A chemically cross-linked form of sodium hyaluronate designed to remain on the skin surface longer and provide sustained hydration. It functions as a humectant and is well tolerated, with the same safety profile as standard hyaluronic acid.

A plant-derived emollient and preservative formed from glycerin and caprylic acid (coconut) that helps retain moisture and supports formula stability through mild antimicrobial activity.

A chemically modified form of hyaluronic acid that improves stability and penetration in skincare formulations. Clinical assessments show it hydrates skin effectively and is well tolerated across sensitive and normal skin types.

A lab-made version of a lipid naturally found in the outer skin barrier. It is added to creams and cleansers to help replace lipids that washing can strip away, and it is not linked to irritation or safety concerns.

A rich plant butter pressed from shea tree nuts, valued for softening and cushioning dry skin. It is generally well tolerated, though very rare allergic reactions have been reported and people with tree nut allergies who are cautious may want to patch test first.

A humectant that holds water at the skin surface for a more hydrated look. No safety concern.

A key structural lipid naturally found in healthy skin that reinforces the barrier and improves hydration. It is well established in skincare formulations and assessed as having excellent safety across all skin types, including sensitive and compromised barriers.

A plant-derived conditioning agent created by hydrolyzing jojoba esters, supporting skin softness and hydration. Jojoba-derived ingredients have a favorable safety profile, though long-term data on this specific form remains limited.

A broken-down form of hyaluronic acid with smaller molecules intended to penetrate more deeply into the skin. It functions as a humectant and is well tolerated, with the same safety profile as standard hyaluronic acid.

A lower molecular weight version of hyaluronic acid designed for better skin penetration. It has been extensively studied and shown to support skin hydration and barrier function with excellent tolerability in diverse formulations and skin types.

A polysaccharide produced by yeast fermentation used as a film-former and thickener in serums and gels. Its safety profile is supported by extensive use in food and cosmetic applications.

A phospholipid emulsifier from soy or sunflower that binds water and oil and helps other ingredients absorb. It is a natural component of skin membranes, well tolerated, and reviewed as safe as used; a soy-derived grade is not a meaningful concern for a soy food allergy because the protein is largely absent.

An amino acid derived emulsifier made from stearic acid and glutamic acid that is increasingly used in natural and clean formulations. It is mild, biodegradable, and presents no known safety concerns for cosmetic use.

Bisabolol is a botanically derived (or synthetically nature-identical) compound used for its calming, anti-irritant reputation in sensitive-skin formulas. Safety reviews and long clinical use have found it well tolerated with a low rate of reported reactions.

A water or bran extract of rice containing ferulic acid, small peptides and starches. It is a traditional East Asian skincare staple with some supporting antioxidant and mild-brightening data, but most of that evidence comes from cell or animal studies rather than large human trials, so the "brightening" claims on finished products go further than the direct evidence.

A soothing, skin-conditioning compound (also found in comfrey root) commonly added to calm and hydrate irritated or sensitive skin. It has a long history of safe use with very low irritation potential.

Chlorphenesin is a preservative subject to an EU maximum concentration limit and has been linked to contact dermatitis in a minority of users, particularly with repeated exposure. Most people tolerate it at the regulated use level without issue.

A preservative derived from caprylic acid (coconut-sourced) with antimicrobial activity that supports formula stability. Available data support its use at cosmetic concentrations.

An undisclosed scent blend that can contain dozens of components. The single most common cause of cosmetic contact allergy, and the blend is not itemized, so you cannot see what is in it.

A biodegradable chelating agent that binds trace metals to stabilize formulas, often chosen as a gentler alternative to EDTA. It is readily degraded in the environment and poses minimal toxicity concerns at cosmetic concentrations.

A linoleic-acid-rich plant oil used as an emollient and, in some small pediatric studies, associated with support of the skin barrier when applied to infant skin. It is well tolerated with a low reported rate of contact reactions.

An aromatic plant extract rich in natural antioxidants, valued in skincare formulations for its protective properties. Published cosmetic assessments indicate it is generally well tolerated, though the botanical origin means some sensitive individuals may react.

A light, low-odor glycol used as a solvent and humectant, extremely common in Korean toners and essences. It has a low reported irritation rate and is graded low concern in published assessments.

A common emulsifier and texture-softener made from glycerin and stearic acid. CIR review of this class found no evidence of reproductive, carcinogenic, sensitizing, or phototoxic effects in the studies examined.

A waxy sterol found naturally in skin and used in cosmetics as an emollient and emulsifier. It supports the skin barrier and is well tolerated across skin types.

A plant-derived emollient oil rich in ricinoleic acid, used in skincare for decades. Contact allergy has been reported but is uncommon relative to how widely it is used in leave-on products.

An antioxidant that helps protect a formula and condition skin. Well tolerated.

A widely used emulsifier and solubilizer that has been in cosmetics and pharmaceuticals for decades. The CIR has assessed it as safe with no known concerns at typical cosmetic concentrations. As with any surfactant, some people with very sensitive skin may experience mild irritation.

A soothing humectant that helps skin and hair look conditioned. Very well tolerated.

A polysaccharide produced by fermentation of fungal cultures, used to thicken and stabilize formulas. It is well tolerated in cosmetics and often chosen by natural-leaning brands. It functions similarly to other gelling agents but comes from a more controlled fermentation source.

A strong alkali used in tiny amounts to adjust the pH of cosmetics to safe, skin-friendly levels. At the pH found in finished products, sodium hydroxide is neutralized and well tolerated.

Xanthan gum is a microbial-fermentation-derived polysaccharide used to thicken and stabilize textures, similarly common in food. Cosmetic panel review of this and related microbial gums found them safe as used, with no meaningful irritation signal at typical concentrations.

A mineral thickener and anti-caking agent widely used in sunscreens and cosmetics to control texture and prevent ingredient separation. CIR has reviewed silica in cosmetic use and found no basis for concern at the levels used topically.

Used in tiny amounts to set a product to skin-friendly pH. No concern at those levels.

A salt derived from citric acid that buffers pH and prevents metal oxidation in formulas. Widely used in food and cosmetics, it is well tolerated at cosmetic concentrations.

A citrus-scented fragrance component. Fine for most, but it oxidizes over time into a known contact allergen, so it must be labelled in the EU.

A floral fragrance component and one of the EU-labelled fragrance allergens. Usually fine, worth watching if you react to scented products.

Benzyl salicylate is a fragrance fixative that also absorbs some UV light. It is on the EU allergen disclosure list, but the evidence suggests it sensitizes fewer people than most other listed fragrance allergens.

A floral, rose-like fragrance compound found in many essential oils. It is one of the 26 EU-designated fragrance allergens, meaning a documented minority of people can develop contact sensitization, so brands must disclose it above set thresholds.

A rose-scented fragrance ingredient found naturally in geranium and rose oil. It is one of the 26 fragrance allergens the EU requires to be labeled by name because a minority of people develop skin sensitization to it, though most users tolerate it without issue.