Skincare Ingredients

Kaolin

Absorbent clay that removes excess oil

Kojic Acid

Kojic acid is a tyrosinase-inhibiting brightening active typically used around ~1–2% (sometimes higher), and it is well-documented to cause stinging, erythema, and irritant dermatitis in a meaningful subset of users, especially when combined with other actives or in low-pH systems. Patch testing and clinical use show it can be both irritating and a potential sensitizer/contact allergen, making reactions more likely in eczema-prone or barrier-impaired patients. Given its frequent intolerance in sensitive populations and the need for cautious introduction, it fits a significant irritancy risk at typical use levels. Safety Notes: In consumer skincare, kojic acid is commonly found in leave-on brightening serums/creams at low levels around 0.1–1% (often in combination formulas to improve tolerance and stability), and in some rinse-off cleansers/soaps around similar or slightly higher levels. High-strength OTC hyperpigmentation products marketed to the general public (not prescription/pro-only) are observed up to about 4% in leave-on creams/serums, with stability (oxidation/discoloration) and irritation risk typically limiting higher real-world use. Regulatory approaches vary by region, so the upper end reflects observed market availability rather than a universally permitted maximum.

Kojyl Methylenedioxycinnamate

Kojyl Methylenedioxycinnamate is a kojic-acid-derived skin-brightening agent used at low concentrations, but kojic acid derivatives have a clinically documented tendency to cause irritant contact dermatitis and occasional allergic reactions in sensitive or eczematous skin. Because robust independent patch-test data on this specific derivative is limited and it is typically used in leave-on formulas (increasing exposure time), I score it as moderate to reflect meaningful irritation risk and the need for patch testing in reactive patients. Safety Notes: Kojyl Methylenedioxycinnamate is a kojic-acid derivative used as a leave-on skin-brightening active; in commercial serums/creams it commonly appears at low supportive levels around 0.1–0.5% as part of multi-ingredient brightening systems. Higher-strength OTC niche “spot corrector” and intensive discoloration products have been marketed up to ~2–3% to claim stronger tone-evening performance while staying within typical solubility/sensory constraints for leave-on emulsions and anhydrous systems. It is uncommon in rinse-off at meaningful levels due to limited contact time, so the observed market range is primarily from leave-on products.

Lactic Acid

Lactic Acid is a gentle alpha‐hydroxy acid (AHA) used primarily for exfoliation, skin renewal, and improved skin tone while also providing humectant benefits. It is effective for anti-aging and texture improvement but may cause mild to moderate irritation at higher concentrations.

Lactobacillus Ferment

Lactobacillus Ferment is typically used at low concentrations as a skin-conditioning/microbiome-supporting ferment or postbiotic, and it is generally well tolerated in routine patch-test experience. However, ferment-derived mixtures can contain residual organic acids, peptides, or impurities that occasionally trigger stinging or dermatitis in highly reactive or eczema-prone skin, so it is not truly inert. Given the overall low but nonzero irritation potential in compromised skin, a gentle score is most consistent with patient-safety expectations. Safety Notes: In mass-market leave-on serums/creams and many rinse-off cleansers, Lactobacillus Ferment is often used at very low levels (~0.01–0.1%) primarily for microbiome-positioning and/or as a supportive ferment-derived skin-conditioning component. Mid-range products commonly sit around ~0.5–3% depending on whether the supplier material is a concentrated ferment filtrate/lysate or a diluted blend. High-strength consumer “probiotic/ferment essence” style products and concentrated ampoules can reach ~5–10% active ferment material (distinct from the often much higher “filtrate/ferment complex” blend percentages listed on marketing copy), with leave-on formats more likely to use the upper end than rinse-off due to contact time and cost constraints.

Lactobacillus Ferment Lysate

Lactobacillus Ferment Lysate is a postbiotic/skin-conditioning ingredient typically used at low percentages (often ~0.1–5%) to support barrier function and reduce visible sensitivity, and it is generally well tolerated in leave-on products. However, as a biologically derived ferment/lysate containing diverse cellular fragments and metabolites, it has a small but real risk of stinging or triggering reactivity in highly compromised eczema-prone skin, especially in formulas that also include acids, alcohols, or multiple preservatives. Given that rare but meaningful sensitivity can occur despite its “gentle” positioning, a conservative gentle score is warranted. Safety Notes: In commercial skincare, Lactobacillus Ferment Lysate is often used at very low levels (~0.05–0.5%) in leave-on serums/creams where it functions as a postbiotic/skin-conditioning active and is frequently part of a broader ferment blend. Dedicated “microbiome” or barrier-support leave-on products (ampoules/serums/essences) and some mask formats can push totals to several percent, with the highest consumer-available products commonly topping out around ~10% when the lysate is a key featured active and the formula can accommodate added solids/viscosity and preservative demands; rinse-off cleansers typically sit toward the low end due to short contact time and cost/processing constraints.

Lactobacillus/Papaya Fruit Ferment Extract

Lactobacillus/papaya ferment extracts are typically used at low concentrations as conditioning/brightening “ferment” ingredients, but they can contain bioactive papaya components (including residual proteolytic enzymes) and organic acids that may sting or disrupt compromised barriers. Clinical patch-test data for this specific ferment is limited and “ferment” labeling is not a guarantee of inertness, so in eczema-prone or post-procedure skin I treat it as a mild irritant with occasional sensitivity potential, especially when layered with other actives. Safety Notes: In commercial leave-on serums/essences and moisturizers, this type of fruit ferment extract is commonly used at low levels (~0.05–1%) primarily for marketing/skin-feel and mild enzymatic/exfoliation claims, with higher loads limited by odor, color, and stability. High-strength consumer “fermented enzyme” masks/peels and exfoliating gels (non-prescription) can reach the upper single digits, with ~5–10% observed when the ferment is positioned as a primary active blend rather than a supporting extract. Rinse-off products often sit toward the higher end compared with leave-on due to reduced irritation/sensory constraints, but both formats exist across the range.

Lactobacillus/Portulaca Oleracea Ferment Extract

This is a skin-conditioning, soothing-type fermented botanical extract typically used at low concentrations (generally <1–3%) and is not inherently exfoliating or pH-disruptive. While purslane-derived extracts and many lactobacillus ferments are usually well-tolerated, ferment byproducts and residual botanical proteins can trigger irritation or rare allergic reactions in highly reactive or eczema-prone skin, especially in compromised barriers. Given that non-standardized ferments have variable compositions and can sensitize a small subset of patients, I rate it as gentle but not inert. Safety Notes: In commercial leave-on products (toners/serums/creams), this ferment extract is frequently used at low labeling-levels (~0.05–0.5%) as a soothing/skin-conditioning adjunct alongside other botanicals and ferments, consistent with supplier guidance for fermented plant extracts. Higher-strength consumer “ferment ampoules” and sensitive-skin concentrates can reach multi-percent use levels, with some niche products formulating up to ~10% (typically as an ingredient blend supplied in a carrier such as butylene glycol/water), while rinse-off cleansers usually sit toward the low end due to cost and limited contact time.

Lactobacillus/Punica Granatum Fruit Ferment Extract

This is a fermented pomegranate extract used mainly for antioxidant/skin-conditioning and microbiome-support claims, typically at low concentrations (often <1–3%). While generally well tolerated, botanical ferment mixtures can contain residual organic acids and diverse fermentation byproducts that occasionally sting compromised barriers or trigger low-rate contact reactions in very reactive/eczema-prone patients. Given the variability between batches and the higher reactivity risk of complex botanicals versus single-molecule humectants, I rate it as gentle but not exceptionally gentle. Safety Notes: In commercial skincare, Lactobacillus/Punica Granatum Fruit Ferment Extract is most often used as a probiotic/ferment “active” or skin-conditioning adjunct at very low levels (~0.01–0.1%) in mass-market toners, cleansers, and creams where it functions mainly as a label-claim/support ingredient. Higher concentrations are seen in consumer-available “ferment essence/serum” style leave-on products and concentrated ampoules, where total ferment extract can reach ~1–5% depending on supplier activity, odor/color tolerance, and stability/preservative system; rinse-off formats typically sit toward the lower end due to cost and limited contact time.

Lactobacillus/Rice Ferment Filtrate

Lactobacillus/Rice Ferment Filtrate is primarily a skin-conditioning/humectant-type ferment used at low-to-moderate levels in leave-on products, but ferments are complex mixtures (organic acids, peptides, residual metabolites) and can sting compromised barriers despite being marketed as “soothing.” Clinical experience and patch-test data across ferment/lysate ingredients show generally low irritation yet a non-trivial rate of reactivity in eczema/very sensitive populations, so I score it as mild rather than “gentle” to reflect real-world flare risk and cumulative use with other actives. Safety Notes: In commercial leave-on products (toners/essences/serums/creams), Lactobacillus/Rice Ferment Filtrate is often used at low levels (~0.1–1%) as part of multi-ferment or “microbiome” blends, where it functions mainly as a skin-conditioning/hydration support ingredient. Higher-strength consumer products marketed as “ferment essences” or rice-ferment concentrates commonly place it near the top of the INCI and can reach ~10–30% active as supplied (still typically water-based filtrate), with rinse-off cleansers usually sitting toward the lower end due to limited contact time. No specific FDA/EU maximum is set for this INCI; practical upper limits are driven by odor, stability, and preservative strategy rather than regulation.

Lactobacillus/Rye Flour Ferment

Lactobacillus/rye flour ferment is used primarily as a skin-conditioning/“postbiotic” ferment filtrate, typically at low percentages, and it is generally well-tolerated in most leave-on formulas. However, fermented grain-derived ingredients can contain a complex mix of organic acids, peptides, and residual grain components that increase variability and can trigger stinging or eczematous flares in highly reactive or atopic patients, so I do not consider it exceptionally gentle. In routine skincare layering, its irritation potential is usually low but not negligible, warranting a cautious 'gentle' score. Safety Notes: In commercial skincare, Lactobacillus/Rye Flour Ferment is most often used as a microbiome-supporting/soothing ferment filtrate at low inclusion levels (~0.05–1%) in leave-on serums, creams, and toners, especially when supplied as a preserved aqueous/glycerin solution and positioned as a minor active. Higher-strength consumer products marketed as “ferment essences/ampoules” or “probiotic/fermented” treatments can reach several percent, and a small number of OTC formulations (typically water-based leave-on masks/essences) are formulated up to ~10% when the supplier material is designed for high dosing; rinse-off products are generally at the lower end due to cost and short contact time.

Lactobionic Acid

Lactobionic acid is a polyhydroxy acid (PHA) exfoliant/humectant typically used around ~2–10% (sometimes higher) at mildly acidic pH; it is generally better tolerated than glycolic/lactic acid due to its larger molecule and slower penetration. However, as an exfoliating acid it can still cause stinging, erythema, and barrier disruption in reactive or eczematous skin—especially when layered with retinoids, benzoyl peroxide, or other acids—so I score it as mild rather than “gentle” for high-risk patients. Safety Notes: In commercial skincare, lactobionic acid (a PHA) is found at very low levels (~0.1–1%) in sensitive-skin toners/serums and multi-acid formulas where it functions as a mild exfoliant/humectant alongside other acids. Most leave-on PHA products cluster around ~2–10%, while the highest consumer-available OTC strengths I’ve observed are ~12–15% in dedicated PHA resurfacing serums/creams marketed for at-home use (higher levels are uncommon due to tackiness, neutralization/pH control needs, and irritation risk even though PHAs are generally milder). Rinse-off cleansers typically sit on the lower end versus leave-on treatments, with performance driven heavily by finished-product pH and buffering rather than % alone.

Lactococcus Ferment Lysate

MVP Approved - Lactococcus Ferment Lysate is a probiotic-derived ingredient used in skincare to support barrier repair, hydration, and soothing of irritation, with low overall irritancy.

Lactoperoxidase

Lactoperoxidase is an enzyme used at low levels in oral-care and some preservative/antimicrobial systems; enzymes are proteins that can irritate compromised skin and have a recognized (though uncommon) potential for delayed sensitization in reactive individuals. While generally well-tolerated at typical cosmetic concentrations, the combination of enzymatic activity and allergy history (often dairy-derived protein) warrants a mild-risk score, especially for eczema-prone or barrier-impaired patients. Safety Notes: In consumer skincare, lactoperoxidase is typically used as part of enzyme-based antimicrobial/“preservative-support” systems (often paired with glucose oxidase/lactoferrin) where effective use levels in leave-on and rinse-off products are commonly in the ~0.0001–0.02% range for the active enzyme due to potency and stability constraints. At the low end, it appears in sensitive-skin creams/lotions and cleansers at trace levels to support microbiological control without adding traditional preservatives. The upper end reflects high-strength, consumer-available enzyme complex formulations and specialty deodorant/body-care products where lactoperoxidase can be present up to ~0.1–0.2% (typically as part of a broader enzyme blend), above which stability, cost, and diminishing returns generally limit use in OTC cosmetics.

Laminaria Digitata Extract

Laminaria digitata (brown algae/kelp) extract is primarily used as a humectant/soothing, antioxidant, and film-forming botanical in low concentrations, and is generally well tolerated in routine moisturizers and serums. However, as a complex natural extract it contains multiple bioactive components and trace impurities that can trigger stinging or allergic contact reactions in a small subset of highly reactive or eczematous patients, so it is not scored as “very gentle” or “inert.” In cumulative routines, it is usually low-risk but still warrants caution for those with known seaweed/iodine sensitivity or frequent botanical reactivity. Safety Notes: In commercial skincare, Laminaria Digitata Extract is frequently used at very low levels (around 0.001–0.1%) in both leave-on and rinse-off products as part of a broader “marine/algae complex,” where it functions mainly as a marketing/antioxidant-humectant support ingredient. Dedicated seaweed/kelp-focused serums, gels, masks, and some cream bases sold OTC can reach ~1–5% extract, typically requiring good preservation and odor/color management due to higher natural extract load. This range reflects observed INCI-listed usage levels for extracts (not purified actives like iodine/alginate fractions), with higher levels more common in leave-on masks/serums than in cleansers.

Laminaria Ochroleuca Extract

Laminaria Ochroleuca (golden seaweed) extract is primarily a soothing/antioxidant, barrier-support ingredient typically used at low percentages (~0.1–2%), and it is generally well tolerated in clinical and consumer use. However, as a marine botanical mixture containing polysaccharides/proteins and trace iodine/other constituents, it carries a small but real risk of irritant or allergic reactions in highly reactive or eczema-prone patients. Given this low-but-nonzero sensitization potential for botanicals, I rate it as gentle rather than “very gentle.” Safety Notes: In commercial skincare, Laminaria Ochroleuca Extract (a brown algae extract typically supplied in a standardized glycerin/butanediol/water carrier) is often used as a soothing/anti-pollution active at very low levels (~0.01–0.1%) in mass-market moisturizers, toners, and rinse-off cleansers where it functions mainly as a supporting botanical. Most leave-on serums/creams cluster around ~0.1–1%, while the highest consumer-available “concentrated” soothing/anti-redness or barrier-repair formulas and ampoule-style products can reach ~2–5% depending on supplier standardization; higher levels are uncommon due to cost, odor/color impact, and stability/sensory constraints rather than regulatory limits.

Laminaria Saccharina Extract

Laminaria saccharina (seaweed/kelp) extract is used mainly as a humectant/conditioning, antioxidant, and soothing agent, typically at low-to-moderate concentrations in leave-on products. While generally well-tolerated, botanical extracts can contain variable protein/polysaccharide fractions and trace contaminants (e.g., iodine/halogens) that increase the chance of stinging, dermatitis, or flare in highly reactive or eczematous skin, and patch-test reactions are reported albeit uncommon. Given this variability and the sensitization potential inherent to complex marine botanicals, I rate it as mild rather than “gentle” for compromised skin. Safety Notes: In commercial leave-on moisturizers, toners, and serums, Laminaria Saccharina Extract is frequently used as a supportive marine/soothing claim ingredient at very low levels (often ~0.01–0.1%) due to odor/color and cost constraints and because many suppliers recommend low-use ranges for standardized extracts. Higher-strength consumer products (marine/algae-focused masks, gel-creams, and concentrated ampoules) commonly formulate within ~1–3%, and a small number of OTC “concentrate”/mask-style products reach about 5% when the extract is supplied as a low-solids liquid or standardized powder designed for higher dosing. There is no specific EU/FDA maximum for this botanical extract; practical limits are mainly stability, sensory profile, and supplier specification (solids content).

Lamium Album Flower Extract

Lamium album (white dead-nettle) flower extract is a botanical skin-conditioning/soothing agent typically used at low concentrations, but robust standardized irritation datasets are limited compared with core emollients. As a plant extract containing multiple phytochemicals, it carries a real (though not high) risk of irritation or allergic contact dermatitis in eczema-prone or highly reactive patients, so I rate it mild rather than “gentle” for compromised skin. Safety Notes: In mass-market leave-on skincare (toners, lotions, creams) and rinse-off cleansers, Lamium album flower extract is typically used at very low levels as part of a botanical blend, with real-world INCI listings consistent with ~0.001–0.05% active extract. More “botanical-focused” OTC serums, essences, and calming/anti-redness products sometimes use dedicated Lamium album extracts at ~0.1–1%. The upper end (~2–3%) is observed in consumer-available high-botanical formulations where the extract is a primary featured ingredient (often supplied in a standardized glycerin/butanediol base), staying within typical stability/sensory limits for leave-on products and not constrained by specific EU/FDA concentration caps for this botanical.

Lanolin

Lanolin is an emollient/occlusive used commonly around 1–20% (and even higher in ointments) to reduce water loss, but it has a well-documented risk of allergic contact dermatitis in a subset of users, especially those with eczema or compromised barriers. While many tolerate highly purified lanolin, patch-testing and clinical reports show sensitization can be clinically meaningful, and irritation/allergy can be harder to distinguish in inflamed skin. Given its frequent use in leave-on products and the higher risk population (atopic dermatitis) it’s often applied to, I score it as moderate and recommend patch testing for sensitive individuals. Safety Notes: In mass-market leave-on creams/lotions and cleansers, lanolin is often used at very low levels (~0.1–2%) as an emollient/co-emulsifier or skin-feel modifier, with mid-range occlusive balms and barrier creams commonly around 5–30%. At the high end, consumer-available nipple/skin protectant products are sold as “100% lanolin” (anhydrous lanolin) or near-neat lanolin, representing the practical maximum for OTC retail. Lanolin is not subject to a specific EU/FDA maximum concentration limit in cosmetics, but allergen/sensitization risk can drive lower use levels in facial leave-on products compared with body/occlusive balms.

Lanolin Alcohol

Lanolin alcohol (wool alcohols) is an emollient fraction of lanolin used in ointments and barrier creams, often at low-to-moderate percentages, but it is a well-documented contact allergen in patch testing. While many users tolerate it, sensitization and flare reactions are notably more common in eczema and chronic dermatitis populations, where barrier impairment increases risk. Given this clinically meaningful delayed hypersensitivity potential in a high-risk group, a moderate irritancy score is the safest evidence-aligned assessment. Safety Notes: In commercial skincare, lanolin alcohol is often used at low levels (~0.05–1%) as an emollient/co-emulsifier and barrier-supporting lipid component in creams, lotions, and some cleansers, with even lower trace levels possible when part of lanolin-derived blends. Higher strengths are seen in consumer-available barrier ointments, lip balms, and intensive hand/heel salves where lanolin alcohol functions as a primary occlusive/emollient, commonly in the 5–20% range and occasionally reaching about 30% in very heavy, anhydrous or high-oil-phase leave-on products; rinse-off products typically sit at the low end due to feel and deposition limits.

Larrea Divaricata Extract

Larrea divaricata (chaparral/creosote bush) extract is a botanical antioxidant/anti-inflammatory used at low concentrations, but it contains resinous phenolics (e.g., NDGA-related compounds) that are recognized causes of contact irritation and occasional allergic contact dermatitis in susceptible individuals. Because standardized clinical patch-test data in modern cosmetic vehicles is limited and plant extracts have higher variability/impurity risk, I score it as moderate and recommend patch testing for eczema-prone or highly reactive skin. Safety Notes: In commercial skincare, Larrea divaricata (commonly positioned as a botanical antioxidant/soothing or antimicrobial extract) is most often included at very low levels (~0.01–0.1%) as part of multi-extract blends in leave-on serums/creams and aftershaves, reflecting typical supplier recommended use rates for standardized extracts. Higher-strength consumer products marketed around oily/acne-prone skin or scalp care (leave-on spot gels/toners and some rinse-off cleansers/shampoos) have been observed using roughly 1–3% when the extract is a named “active” and the formula is built around it; above this becomes uncommon due to odor/color, solubility, and tolerability constraints typical of resinous Larrea extracts.

Larrea Tridentata Extract

Larrea tridentata (creosote bush) extract is a botanical antioxidant/anti-inflammatory used at low percentages, but it contains resinous phenolics (e.g., NDGA-related constituents) that can be irritating and have a meaningful rate of reactivity in sensitized or eczematous skin. As with many plant extracts, variability in composition and co-extracted compounds increases the likelihood of stinging, redness, or dermatitis when used in leave-on products, especially in compromised barriers. Given the higher-risk sensitive-skin population and limited robust safety data compared with inert excipients, it warrants cautious introduction and a notable irritancy score. Safety Notes: Larrea tridentata (creosote bush) extract is most often used as a minor botanical antioxidant/soothing component in leave-on serums, moisturizers, and after-sun products at trace-to-low levels (typically ~0.01–0.5%), consistent with supplier use-level guidance for complex plant extracts. High-strength consumer products (botanical spot treatments, “concentrated” desert-plant serums, and some natural deodorant/antimicrobial-style balms) can push the extract to a few percent; the upper end (~5%) reflects the highest OTC levels observed where the extract is a primary featured active, with sensitization/odor/color and stability constraints usually limiting use above this in mainstream formulations.

Laurdimonium Hydroxypropyl Hydrolyzed Soy Protein

Laurdimonium Hydroxypropyl Hydrolyzed Soy Protein is a cationic, quaternized hydrolyzed protein used mainly as a conditioning/anti-static agent in hair and rinse-off skin products, typically at low percentages. While hydrolyzed proteins are usually well tolerated, the cationic surfactant-like laurdimonium modification increases binding to skin/hair and can provoke stinging or irritant reactions in compromised barriers (eczema, post-procedure), and soy-derived proteins carry a small but real sensitization/allergen concern in highly reactive individuals. Given the potential for irritation in sensitive populations despite generally low use levels, a mild score is the safest clinically-aligned assessment. Safety Notes: In commercial hair and scalp products this cationic, quaternized hydrolyzed soy protein is most often used at low levels (~0.05–0.3%) as a conditioning/anti-static additive in rinse-off shampoos and conditioners, where deposition is aided by its positive charge. Higher-strength consumer-available leave-on treatments (e.g., spray conditioners, anti-frizz creams, repair masks/serums) commonly push total use levels into the ~0.5–2% range, with a small number of specialized “protein repair/bonding” style products reaching about 3% while still maintaining stability and sensory acceptability. There are no specific FDA/EU maximum concentration limits for this INCI, so the upper end is primarily constrained by formula feel, build-up, and compatibility with other cationic or anionic systems.

Laurdimonium Hydroxypropyl Hydrolyzed Wheat Protein

Laurdimonium hydroxypropyl hydrolyzed wheat protein is a cationic, quaternized hydrolyzed protein used mainly in hair/skin conditioning at low concentrations, and it is generally tolerated on intact skin. However, cationic conditioning agents can be more irritating than nonionic humectants, and hydrolyzed wheat proteins carry a non-zero risk of allergy/sensitization in susceptible individuals—particularly those with eczema or barrier compromise—so I rate it as mild with occasional sensitivity possible. Safety Notes: This cationic, quaternized hydrolyzed wheat protein is typically used as a conditioning/deposition aid in hair conditioners, masks, leave-in sprays, and 2-in-1 shampoos, with many mass-market products using it around 0.1–0.5% active for slip and antistatic benefits. At the low end (~0.05%), it appears in light rinse-off shampoos or as a minor component of a conditioning complex/blend. High-strength consumer products (intensive masks/leave-ins marketed for damage repair or strengthening) can reach ~1–3% active, with higher levels generally limited by feel, build-up, and potential irritation rather than specific global concentration caps for this INCI.

Laureth-23

Laureth-23 is an ethoxylated fatty alcohol used primarily as a surfactant/solubilizer in cleansers and leave-on formulations, typically at low-to-moderate percentages, but surfactants as a class can disrupt the stratum corneum and increase stinging—especially on compromised or eczematous skin. Human patch testing and real-world use suggest it is generally tolerated but not reliably “non-irritating,” with higher risk when combined with other cleansing agents or when barrier function is impaired. Given cumulative routine exposure and the vulnerable sensitive-skin population, I rate it as a moderate irritant where patch testing is prudent. Safety Notes: Laureth-23 is a high-HLB nonionic surfactant/solubilizer most often used at very low levels (~0.05–1%) in leave-on lotions/serums and as a solubilizer for fragrance/oils, while rinse-off cleansers and body washes commonly sit around ~1–8% as part of the primary surfactant system. In consumer-available high-surfactant formats (e.g., micellar waters, makeup removers, cleansing oils/gel cleansers, and some bath/shower concentrates), it can reach ~10–20% within the total surfactant/solubilizer blend without being professional-only. No specific EU/FDA maximum applies for this INCI; practical limits are driven by irritation potential and viscosity/cloud point constraints, with higher levels more typical for rinse-off than leave-on.

Laureth-3

Laureth-3 is an ethoxylated fatty alcohol used primarily as a surfactant/solubilizer in cleansers and emulsions, commonly at low single-digit percentages, but its irritation risk rises with leave-on exposure and higher surfactant load. Clinically, nonionic surfactants like Laureth compounds are generally milder than anionics, yet they can still disrupt the stratum corneum barrier and provoke stinging, dryness, or eczema flares in reactive skin—especially when layered with other actives or used frequently. Given real-world cumulative exposure in routines and the vulnerability of compromised skin, a moderate score is the safest clinically-aligned assessment. Safety Notes: Laureth-3 is typically used as a nonionic surfactant/solubilizer and co-emulsifier, and I’ve observed it at very low levels (~0.05–0.3%) in leave-on lotions/creams and facial oils to aid fragrance/active solubilization and improve rinse-feel. In rinse-off cleansers, shampoos, and bath products it more commonly appears around ~0.5–3% as part of the total surfactant system, but consumer-available high-detergency or specialty cleansing concentrates can push Laureth-3 up to ~5–8% when it is a primary surfactant/solubilizer component. This ingredient is not specifically concentration-restricted by EU/FDA, so practical upper levels are usually set by mildness/irritation and formula viscosity/clarity targets rather than regulation.

Laureth-4

Laureth-4 is an ethoxylated nonionic surfactant/solubilizer used in cleansers and as a penetration enhancer, typically around ~1–10% (and sometimes higher in rinse-off systems), where it can disrupt stratum corneum lipids and increase transepidermal water loss. Clinically, ethoxylated lauryl/laureth surfactants show meaningful irritancy in patch testing and are a common trigger for stinging/burning in eczema-prone or barrier-compromised skin, especially with repeated exposure in multi-step routines. Given its barrier-disruptive potential and the heightened risk in sensitive populations, it warrants a significant irritancy rating. Safety Notes: Laureth-4 is most often used as a nonionic surfactant/solubilizer and penetration-aid in leave-on lotions/serums and cleansing oils at low levels (~0.05–1%), where it helps solubilize fragrance/oils and improve sensory without overt detergency. In rinse-off cleansers, makeup removers, and emulsified cleansing oils/balms, it commonly runs ~1–10% as part of the surfactant system; the highest consumer-available levels are seen in anhydrous/emulsifying cleanser concentrates and niche high-solubilizer formulas where Laureth-4 can reach ~15–25% to self-emulsify oils and remove heavy makeup. There is no specific EU/FDA maximum concentration limit for Laureth-4 as such (it is generally governed by overall product safety/irritation potential), so the practical upper bound is set by tolerability and formula performance, with leave-on products typically staying much lower than rinse-off.

Laureth-7

Laureth-7 is an ethoxylated nonionic surfactant/solubilizer commonly used in cleansers and emulsions (often ~0.5–5%), where surfactant activity can disrupt the stratum corneum and increase transepidermal water loss. Human patch and in-use data for ethoxylated alcohol surfactants show low-to-moderate irritation potential that rises with concentration, leave-on exposure, and compromised barriers (eczema, post-procedure). Given the real-world cumulative exposure from multi-step routines and higher risk in barrier-impaired patients, a moderate irritancy score is the safer clinically aligned assessment. Safety Notes: Laureth-7 is a nonionic surfactant/solubilizer commonly used at very low levels (~0.05–0.5%) in leave-on products (serums, lotions, sunscreens) to solubilize fragrance/oily actives and support emulsion stability. In rinse-off cleansers, micellar waters, and foaming washes it is more often a secondary surfactant/co-surfactant in the ~1–8% range, but consumer-available high-foaming or clarifying washes and some rinse-off hair/body wash formats can reach ~10–15% when used as a primary/major surfactant within the total surfactant system.

Laureth-7 Citrate

Laureth-7 Citrate is a citrate salt of an ethoxylated fatty alcohol used primarily as a solubilizer/surfactant, typically at low percentages in leave-on products but capable of disrupting the skin barrier depending on the overall formula and cleansing load. Ethoxylated surfactants (including Laureth derivatives) have a documented history of causing mild irritant contact dermatitis in patch testing, with higher risk in eczema-prone or compromised skin, especially when combined with other surfactants or actives. Given the sensitive-skin population and cumulative routine exposure, I score it as mild (0.4) rather than gentle. Safety Notes: Laureth-7 Citrate is used commercially primarily as a solubilizer/surfactant and emulsifier, with low-end usage (~0.05–0.3%) seen in leave-on lotions/serums and micellar-type waters to aid fragrance/oil solubilization and mild cleansing. In rinse-off facial cleansers, body washes, and makeup removers it more commonly appears around ~1–5% as part of the surfactant system, while high-strength consumer products (especially oil cleansers, cleansing balms, and concentrated cleanser bases) can reach ~8–10% to achieve solubilization and cleansing performance without being prescription/professional-only.

Lauric Acid

Lauric acid is a saturated fatty acid used as an emollient/surfactant component (often as part of soaps or as a fatty-acid fraction) and, while generally well-tolerated on intact skin, free fatty acids can be irritating at higher leave-on levels and in compromised barriers. In clinical patch testing, irritation is more likely when it contributes to higher pH cleansing systems or when used on eczematous skin, where it can sting and worsen dryness. Given real-world cumulative exposure (cleansers, occlusive balms, and acne products) and the heightened reactivity of sensitive populations, I rate it as mild with occasional sensitivity risk. Safety Notes: In commercial skincare, lauric acid most often appears at very low levels (~0.01–0.5%) as a minor fatty-acid component of emulsifier systems or as a declared constituent alongside other fatty acids in cleansers and creams. Mid-range use (~1–10%) occurs in cleansing bars, surfactant/soap-type systems, and some antimicrobial/anti-acne oriented rinse-off products where free lauric acid contributes to cleansing/foam and antimicrobial effect. The highest consumer-available levels are found in high-lauric, anhydrous or soap-type formulations (e.g., lauric-acid–rich bar/solid cleansers or specialty antimicrobial products) where lauric acid can be used as a primary structurant/fatty acid at ~20–30%; such high levels are uncommon in leave-on products due to irritation potential and sensory constraints.