Ultimune Power Infusing Serum

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

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

A lightweight humectant and solvent similar in role to propylene glycol, used to carry actives and give lotions a lighter feel. CIR has reviewed it and considers it safe as used 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.

A silicone that gives a smooth, soft feel and helps hold water in the skin. Inert and well studied.

A disaccharide sugar that acts as a humectant, drawing moisture into the skin and helping prevent dryness. It is well tolerated and commonly found in skincare formulas designed to support skin barrier health.

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.

A hydrosol from damascena rose flowers, used as a skin toner and fragrance. Rose can trigger allergic contact dermatitis in sensitive individuals, though the hydrosol form is generally well tolerated. People with a history of plant sensitivities should patch test.

A natural osmolyte produced by halophilic bacteria. Used for hydration and protective stress response, ectoin is well tolerated with emerging evidence for skin barrier support and soothing. No safety concerns flagged in cosmetic applications.

A lightweight plant oil pressed from camellia seeds, valued for its conditioning and antioxidant properties in skincare. It is generally well tolerated across skin types, though people with plant seed allergies should patch test first.

A leaf extract long used in Korean and Chinese folk medicine and popularized in K-beauty as "heartleaf." Small in-vitro and cell-culture studies suggest anti-inflammatory and antioxidant activity, but there is little rigorous human clinical trial data isolating the extract itself, so soothing claims should be read as plausible rather than proven.

A smooth synthetic emollient ester used to soften skin and carry oil-soluble ingredients. 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.

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.

Used like sodium hydroxide to adjust pH in cosmetics at very low levels. At finished-product pH, it is neutralized and well tolerated.

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.

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

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.

A small-dose synthetic antioxidant that prevents oils and fragrance in a formula from oxidizing. Not shown to pose a toxicological risk at the levels used in cosmetics.

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

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

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.

The sodium salt of benzoic acid, used as a preservative in both foods and cosmetics. Decades of safety review support its use at typical cosmetic concentrations, with mild irritation the main reported issue in sensitive skin.

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.