Acglicolic Facial Serum

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

The smallest and most penetrating alpha hydroxy acid, used to loosen the bonds between dead skin cells for smoother texture and tone. It is a genuine irritant at higher concentrations or low pH, can increase sun sensitivity, and the EU restricts free acid content and requires sunscreen-use wording on labeling.

A silicone-based conditioning agent that improves slip and spreadability in formulas while hydrating the skin surface. Silicones in cosmetics are inert, non-absorbable, and rinse away cleanly.

A light synthetic emollient that gives creams a smooth, non-greasy slip, a common alternative to mineral oil in Korean formulas. It sits on the skin surface and is graded low concern in published assessments.

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 solvent and emollient ester used in leave-on and rinse-off formulas. The CIR Expert Panel reviewed alkyl benzoates and found no irritation even at full strength, with typical use levels ranging from 0.0008 to 50 percent depending on product type.

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 lightweight, volatile silicone that gives serums and primers their silky slip and quick-evaporating finish. Human safety data are reassuring; the EU restriction on this ingredient in rinse-off products is about environmental persistence in waterways, not skin safety.

A synthetic polymer used to thicken and stabilize water-based formulas like gels and serums. It provides texture and suspension of particles without interfering with skin feel. Well established in cosmetics.

A fast-evaporating solvent used to carry actives and give toners a light, "clean" feel; at the concentrations used in classic astringents it can be genuinely drying or irritating with repeated use, especially on dry or compromised skin, though it is not inherently toxic and is a normal, well-studied cosmetic ingredient.

Alpha-isomethyl ionone is a violet-scented fragrance material and one of the EU-listed allergens requiring label disclosure. Documented sensitization is more common with this ingredient than with many other listed fragrance allergens.

A gentle, stable vitamin C derivative that the skin converts to active vitamin C, popular for brightening with less irritation than pure ascorbic acid. It is well tolerated and graded low concern in published assessments.

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.

Carbomer is a synthetic polymer used purely to thicken and stabilize gels and lotions, with negligible skin penetration due to its large molecular size. Safety reviews have found low toxicity and minimal irritation potential even in leave-on use.

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.

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 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 blend of cetyl and stearyl fatty alcohols used to thicken lotions and soften skin. It is chemically unrelated to drying alcohols like ethanol, and the CIR expert panel has found fatty alcohols safe as used in cosmetics.

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 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 chelating agent that binds trace metal ions to keep formulas stable and preservatives working properly. It is not a functional skincare "active" and only a very small amount is used, with minimal skin penetration expected.

An amino acid antioxidant found naturally in mushrooms and some bacteria, emerging in cosmetics for its free-radical quenching properties. Limited human cosmetic studies exist, but ergothioneine is well tolerated in food and supplement forms, with low hazard potential indicated in available assessments.

A preservative that keeps products free of mold and bacteria. Reviewed repeatedly and considered safe at the low levels used.

A jasmine-like fragrance compound frequently used in soaps and lotions. It is one of the 26 EU-designated fragrance allergens, though studies suggest its sensitization potency is comparatively low relative to other listed allergens.

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.

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.

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 widely used preservative, safe at the legal limit of 1% or less. Often the "paraben-free" replacement.

A plant-derived lipid precursor found naturally in skin that supports barrier function and lipid composition. It is used in skincare formulations to strengthen the stratum corneum and is documented as well tolerated, though rare individual sensitivities may occur.

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 small humectant and solvent molecule that helps other ingredients dissolve and helps skin hold water. It is one of the most studied cosmetic ingredients and is considered safe at the concentrations used in personal care products.

A member of the paraben family used to prevent microbial growth in cosmetics. Like methylparaben, it has been reviewed extensively and found safe at the concentrations used in leave-on and rinse-off products.

Ordinary salt, used in surfactant-based products like shampoos and body washes to adjust viscosity by interacting with the surfactant micelles. It has no meaningful toxicity concern at cosmetic use levels; the main practical downside is that too much can make a formula feel less mild.

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

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.

A mild surfactant and emulsifier made from lactic acid and lauric acid. The lactate component makes it less irritating than many other surfactants; generally well tolerated in both rinse-off and leave-on formulas.

A more stable, esterified form of vitamin E used as an antioxidant and skin-conditioning ingredient. It is a different substance from the vitamin E acetate implicated in vaping-related lung injury, which involved inhaling the oil, not applying it topically to skin.

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.