Leave-In Conditioner

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

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 long-chain quaternary ammonium compound used in rinse-off conditioners and leave-on styling products for conditioning and static control. It is well documented in cosmetic use with a strong 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 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 rich botanical oil from avocado fruit, used to nourish and soften the skin. It is generally well tolerated across skin types and provides conditioning benefits.

Tea tree oil is used for its antimicrobial reputation in blemish-focused products, but it is a genuine, well-documented contact sensitizer, and its allergy potential rises sharply once the oil has oxidized from air exposure. Fresh, well-preserved, low-concentration formulations are much lower risk than old or improperly stored oil.

Technically a liquid wax ester rather than a true oil, jojoba closely resembles skin's own sebum and absorbs without feeling greasy. It is well tolerated across skin types, including acne-prone skin, with no significant irritation or comedogenicity signal in the available data.

A fatty-acid and tocopherol-rich plant oil used as a hair and skin emollient; CIR's review of plant-derived fatty acid oils found no evidence of irritation or sensitization and a long history of safe use in food and cosmetics.

A rich, solid-at-room-temperature oil that deeply softens dry skin and hair. It is well tolerated overall, but its high lauric acid content is considered comedogenic by many dermatologists, so it can trigger breakouts in people who are acne-prone.

A nutrient-rich oil pressed from sweet almond kernels, used to soften and condition skin. It is generally well tolerated, though people with tree nut allergies should patch test first, as it can rarely trigger allergic reactions.

A plant-derived water or extract used mainly as a soothing humectant filler. Evidence for dramatic skin benefits beyond mild hydration and soothing is limited, but it is well tolerated by most people.

A plant-derived emollient oil rich in ricinoleic acid, used in skincare for decades. Contact allergy has been reported but is uncommon relative to how widely it is used in leave-on products.

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

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

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

A silicone-based polymer with amino groups that deposits on hair to provide conditioning and smoothing benefits. It is extensively used in hair care products with a long track record of safe use in rinse-off formulations.

A positively charged conditioning polymer used in shampoos and conditioners to reduce frizz and improve manageability. It is well tolerated and has been safely used in cosmetics for decades.

A quaternary ammonium salt used as a conditioning and antistatic agent in hair products. It has been extensively documented as safe in cosmetics when used in typical rinse-off formulations.

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

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 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.

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 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.

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.

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.

Hydroxycitronellal is a lily-of-the-valley scented fragrance ingredient on the EU allergen disclosure list. It has well-documented sensitizing potential in patch-test studies, so it is worth checking the label if you have known fragrance sensitivities.

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 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 sweet, hay-like fragrance ingredient naturally found in tonka bean and lavender. It is one of the 26 EU-designated fragrance allergens and is also subject to an EU maximum concentration limit in finished cosmetic products.