Flash Serum

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

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 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.

This branched hydrocarbon is one of the isoparaffins the CIR Expert Panel reviewed and found safe as used in cosmetics, including as an emollient in leave-on face creams. It is generally considered non-comedogenic and used mainly to give a lightweight, non-greasy skin feel.

A synthetic polymer used to create film-forming serums and gels. It is stable, non-irritating, and widely used in cosmetic formulations to improve texture and adherence without toxicological concerns.

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 silicone with phenyl groups that provides conditioning and a refined feel in foundations and color cosmetics. It is inert and well tolerated across skin types.

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

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 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.

The sodium salt of lactic acid and a key component of the skin barrier and natural moisturizing factor that attracts water to the skin. It is well established as a safe and effective humectant with no known hazards at cosmetic concentrations.

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

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

A signal peptide attached to palmitic acid that activates collagen synthesis in skin cells. Well tolerated across skin types with no significant safety concerns in cosmetic use.

A peptide lipid that mimics collagen fragments and signals skin cells to increase collagen production while reducing inflammation. Established in anti-aging formulas with a consistent safety record.

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 common preservative and fragrance/solvent ingredient found naturally in many essential oils. It is well tolerated by most people at the levels used in cosmetics, but it is one of the 26 EU-designated fragrance allergens and can trigger reactions in people with an existing sensitivity.

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 naturally occurring mineral silicate that adds shimmer and light-diffusing properties to cosmetics. Cosmetic-grade mica is well tolerated and should be free of asbestos and talc contamination.

A cross-linked polymer used to thicken formulas and create lightweight gel textures. The large molecular weight prevents penetration into the skin and is not absorbed; well tolerated in cosmetics.

A mineral UV filter and white pigment used in sunscreens and makeup. It sits on the skin surface rather than being absorbed, and major regulators consider it safe for topical cosmetic use.

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

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.

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 volatile alcohol used as a solvent to dissolve fragrance and active ingredients in cosmetics. Published assessments support its safe use at concentrations found in cosmetic formulations.

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

A widely used, gentle preservative also common in food. It is generally well tolerated, though it can occasionally cause mild, transient irritation in people with already-compromised or very reactive skin.