Professional-C Serum 20%

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.

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

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 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 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 glycol-based humectant and solvent widely used in rinse-off and leave-on cosmetics. Published safety assessments find it well tolerated at the concentrations used in cosmetic formulations.

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

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

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.

An essential oil from grapefruit peel rich in limonene and other furocoumarins. It is a fragrance allergen that carries phototoxicity risk, particularly in sun-exposed areas; some formulations concentrate enough to cause phototoxic reactions in sensitive individuals.

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 gentle, sugar-derived surfactant that is milder than sulfates and works through natural emulsification without the irritation profile of harsher cleansers. It is well-established in rinse-off and leave-on formulations.

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

A fragrance fixative and solvent found naturally in balsams and used to help scents last longer. It is one of the 26 EU-designated fragrance allergens, with documented but uncommon contact sensitization.

Amyl cinnamal is a synthetic jasmine-like fragrance material on the EU list of allergens requiring disclosure. It has shown sensitizing potential in some human and animal studies, so fragrance-sensitive users may want to check the label.

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 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.