No.5 Vitamin Concentrated Serum

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

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 form of vitamin B3 used to support a more even-looking tone and a comfortable barrier. Well tolerated at cosmetic levels.

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

Tranexamic acid is used topically at low concentrations to help even the look of dark spots and redness-related discoloration. It has an extensive systemic safety record as an oral medicine, and topical skin absorption is minimal, though a dedicated cosmetic-specific safety review has not yet been published by the main cosmetic safety panels.

A glycol used very widely in Korean and Western skincare as a lightweight humectant, solvent, and gentle preservative-booster, often in place of traditional preservatives. It has a low reported irritation rate at use levels and is graded low concern in published assessments.

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 humectant sugar alcohol that draws water into the skin. It is well tolerated and widely used in skincare and food. Not known to cause concern at the concentrations used in cosmetics.

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.

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

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 stable vitamin C derivative used to brighten and provide antioxidant support, more shelf-stable than pure ascorbic acid. It is generally well tolerated, though strong vitamin C forms can sting sensitive skin.

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.

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 buffering agent used in tiny amounts to set a product's pH, most often alongside gel-forming polymers. It is graded low concern in published assessments at the levels used.

A glycerin derivative used as a skin conditioner and preservative booster, often paired with phenoxyethanol to allow lower total preservative levels. It has a low irritation and sensitization profile in safety reviews.

A probiotic-derived ferment lysate containing amino acids and polysaccharides. Limited published research suggests it may benefit skin hydration, though the cosmetic evidence base is smaller than for established ingredients.

A naturally occurring nucleoside used in anti-aging formulas, often marketed for smoothing the look of fine lines. It has a low irritation profile and no established hazard at cosmetic use levels.

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 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.

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

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 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.

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 polysaccharide extracted from yeast cell walls or oat bran. Used for hydration and skin conditioning, beta-glucan is well tolerated with emerging evidence for supporting skin barrier function. No safety concerns flagged in cosmetic use.

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

The most well-studied form of topical vitamin C, used as an antioxidant and to support collagen signaling and brighten uneven tone. It is acidic and can sting or irritate sensitive skin, and it oxidizes readily once a bottle is opened, which can reduce its effectiveness rather than create a safety issue.

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.

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.

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