Skincare Ingredients

Allantoin Glycyrrhetinic Acid

Allantoin Glycyrrhetinic Acid is typically used as a soothing/anti-irritant complex (allantoin plus glycyrrhetinic acid from licorice) at low concentrations in barrier-support and post-procedure products. Both components are generally well-tolerated in clinical use, with glycyrrhetinic acid showing low irritancy in standard cosmetic concentrations, though rare contact allergy to licorice-derived constituents can occur in highly reactive individuals. Given its intended calming function and low sensitization rate but acknowledging non-zero allergy potential, it fits best as very gentle rather than inert. Safety Notes: In commercial OTC skincare, this soothing/anti-irritant complex is typically present at very low levels (~0.01–0.1%) in mass-market creams, toners, aftershaves, and cleansers where it functions as a supportive calming agent rather than a primary active. Leave-on sensitive-skin serums, post-procedure recovery products sold to consumers, and targeted redness/spot-care formulas can reach ~0.5–2.0% total, reflecting the upper end seen in high-strength OTC offerings (higher levels are uncommon due to solubility, sensory, and stability constraints). Rinse-off products generally sit toward the low end because contact time is short and higher loading offers limited incremental benefit.

Allyl Methacrylates Crosspolymer

Allyl Methacrylates Crosspolymer is an inert, high–molecular weight crosslinked polymer used at low levels as a thickener/film former, and it is not bioactive or pH-dependent at typical cosmetic use concentrations. Clinical irritation potential is generally very low, with reactions more likely related to mechanical residue or impurities than the polymer itself. For severely compromised or post-procedure skin, I still assign a small nonzero risk out of caution because acrylate-derived materials can rarely be implicated via trace residual monomers/processing contaminants. Safety Notes: Allyl Methacrylates Crosspolymer is used as a texturizer/absorbent polymer for slip, soft-focus, and oil-control; in many leave-on lotions, sunscreens, and primers it appears at very low levels (about 0.05–0.3%) to tweak sensory and stabilize feel without thickening. In mattifying primers, blurring powders/solid formats, and high-oil-absorption “pore-filling” leave-on products, it can be a primary structuring/feel component and is seen in the low single digits up to ~8% in consumer OTC products. Rinse-off products typically sit toward the low end because the sensory benefit is less persistent, while high-end leave-on color/complexion-adjacent skincare drives the upper bound.

Almond/Borage/Linseed/Olive Acids/Glycerides

This is a blend of fatty acid glycerides derived from plant oils, used primarily as an emollient/surfactant-like skin-conditioning agent typically at low to moderate concentrations in moisturizers and cleansers. Fatty acid glycerides are generally well tolerated and can support barrier function, with low rates of irritant reactions in patch testing compared with true actives. Because it is derived from multiple botanical sources (and may contain minor residuals from processing), occasional sensitivity is still possible in highly reactive or eczema-prone patients, but overall irritancy potential remains very low. Safety Notes: This mixed botanical fatty acid/glyceride complex is most often used as an emollient/skin-conditioning lipid, where it appears at low levels (~0.05–0.5%) in lotions, serums, and cleansers to support barrier feel and slip without greasiness. Mid-range use (1–10%) is common in leave-on creams/balms and lipid-replenishing body products. The upper end (10–25%) is observed in consumer-available high-lipid anhydrous balms, intensive barrier creams, and massage/oil-gel type products where it functions as a primary emollient phase component; rinse-off products typically sit at the lower end due to cost and sensorial constraints.

Aloe Barbadensis Leaf

MVP Approved - Aloe Barbadensis Leaf is prized for its soothing, anti‐inflammatory properties that help calm irritated skin and reduce visible redness.

Aloe Barbadensis Leaf Extract

Aloe barbadensis leaf extract is primarily used as a soothing/humectant botanical in leave-on products, typically at low percentages, and is generally well tolerated. However, clinical and patch test literature documents occasional irritant reactions and rare allergic contact dermatitis (more likely with less purified extracts containing anthraquinones/latex components), which can be clinically meaningful in eczema-prone or highly reactive skin. Given variability in extract purity and real-world sensitization risk, I rate it as mild rather than universally gentle for compromised skin. Safety Notes: In mass-market emulsions (lotions, sunscreens, cleansers) Aloe Barbadensis Leaf Extract is frequently used at trace “labeling/soothing” levels around 0.001–0.1%, especially when the INCI refers to a powdered/standardized extract. In leave-on gels, after-sun products, and ‘high-aloe’ calming serums, consumer products commonly use 1–10% extract equivalents and can reach ~15–20% when formulated with concentrated liquid extracts rather than reconstituted aloe juice; higher claims are typically achieved with Aloe Barbadensis Leaf Juice or Juice Powder, not the extract INCI. Rinse-off products tend to sit at the low end due to cost and limited deposition, while leave-on soothing products drive the upper end.

Aloe Barbadensis Leaf Juice

Aloe barbadensis leaf juice is primarily a soothing/humectant botanical used at relatively high levels in gels and lotions, and it is generally well tolerated in controlled studies and routine use. However, patch testing and case reports document occasional irritant or allergic contact reactions (often influenced by processing impurities or concomitant preservatives), and compromised eczema skin can be especially reactive. Given this non-zero but typically low risk profile, it fits best as “gentle” rather than exceptionally gentle or inert. Safety Notes: In mass-market lotions, cleansers, and toners, Aloe Barbadensis Leaf Juice is often used at trace-to-support levels (≈0.1–5%) primarily for marketing/soothing claims, especially when the formula is otherwise water-based. Many gels, mists, and after-sun/soothing products position aloe as the main base and are formulated with very high aloe juice content (commonly 50–95%+), and consumer-available “100% aloe” gels/juices typically contain ~95–99.5% aloe juice with the remainder being preservatives, humectants, and stabilizers; both leave-on and rinse-off products exist, but the highest concentrations are mainly leave-on gels/sprays.

Aloe Barbadensis Leaf Juice Powder

Aloe barbadensis leaf juice powder is primarily a soothing/humectant botanical used at low concentrations, and it is generally well tolerated on intact skin. However, clinical reports and patch-test data show occasional irritant reactions and rare allergic contact dermatitis to aloe components, with higher risk in compromised eczema-prone skin and when combined with other sensitizers in a routine. Given this non-zero sensitization potential despite its “gentle” reputation, a cautious gentle score is warranted. Safety Notes: In mass-market leave-on lotions, toners, and cleansers, aloe leaf juice powder is often used at trace levels (~0.001–0.05%) to support an “aloe” claim or provide minor soothing while keeping cost and solubility manageable. Many mainstream soothing gels/creams and after-sun products use it around ~0.1–1% depending on the supplier’s reconstitution ratio/potency. High-strength consumer-available powders and “aloe concentrate” gels can reach ~2–5% aloe leaf juice powder (sometimes paired with additional aloe extracts), with the practical upper end driven by viscosity/film-forming, solubility, potential tackiness, and preservative/stability constraints in leave-on systems; rinse-off products typically sit toward the lower end.

Alpha-Arbutin

Alpha-arbutin is a tyrosinase-inhibiting brightening agent typically used around 1–2% in leave-on products and is generally well tolerated in clinical and consumer use. Irritation and stinging can occur, especially on compromised barriers or when layered with exfoliating acids/retinoids, but it is not considered a strongly irritating active at standard concentrations. Given the small but real risk in highly reactive/eczema-prone skin, it fits best as a gentle ingredient rather than “very gentle.” Safety Notes: In consumer skincare, alpha-arbutin is most often found in leave-on brightening serums/creams, with low-end usage around 0.1–0.5% in multi-ingredient tone-evening products where it is a supporting active. The most common “hero” serum strength on the mass and prestige market is 2%, while a smaller number of high-strength OTC specialty formulations are sold at 3% (typically anhydrous or tightly pH-controlled water-based systems to manage stability and discoloration risk). Rinse-off products (cleansers/soaps) tend to sit at the lower end due to short contact time and limited justification for higher dosing.

Alpha-Glucan

Alpha-glucan is a glucose-derived polysaccharide used as a prebiotic/humectant and skin-conditioning agent, typically included around 0.1–5% in leave-on products. Available safety assessments and human use experience indicate a very low rate of irritation or sensitization, with reactions being uncommon and usually tied to overall formula factors rather than the polymer itself. For severely reactive or eczematous skin I still avoid calling it “exceptionally gentle” because any bioactive/prebiotic support ingredient can be a minor trigger in a small subset, but clinically it remains very gentle at typical concentrations. Safety Notes: In commercial skincare, alpha-glucan is most often used as a prebiotic/humectant support active: at the low end (~0.05–0.2%) it appears as a minor microbiome-support claim ingredient in serums, toners, and cleansers (often within blends). Typical leave-on products sit around ~0.5–2%, while the highest consumer-available “microbiome/prebiotic concentrate” leave-on formulations reach ~3–5% as a primary functional active; rinse-off products generally use the lower end due to short contact time and cost. There is no specific EU/FDA cosmetic concentration limit for alpha-glucan, so observed maxima are driven by sensorial/stability and raw material practicality rather than regulation.

Alteromonas Ferment Extract

Alteromonas Ferment Extract is a marine bacterial ferment used in low concentrations as a soothing/humectant bioactive (often marketed for barrier support and anti-irritation). Available safety and in-use data for similar ferment extracts generally show low rates of irritation/sensitization, but as a biologically derived mixture it can still trigger reactions in highly reactive or eczema-prone individuals, especially in compromised skin. Given the overall low irritancy profile yet non-zero risk inherent to ferments, it fits a very gentle (not inert) score. Safety Notes: In mass-market leave-on skincare (serums, moisturizers, eye products) and rinse-off cleansers, Alteromonas Ferment Extract is commonly used at very low levels (around 0.01–0.1%) as a bioferment/skin-conditioning active supplied in diluted carrier solutions. Higher-end barrier/soothing products and specialized “post-procedure”/anti-pollution formulas sometimes push the supplier-recommended usage into the low single digits; the upper end (~5%) reflects high-load consumer-available leave-on products using concentrated ferment solutions (not prescription or in-office), with viscosity/odor/color and preservative demand typically being the practical limiting factors rather than regulatory limits.

Althaea Officinalis Root Extract

Althaea officinalis (marshmallow) root extract is primarily a soothing, film-forming humectant rich in mucilage/polysaccharides and is typically used at low percentages in leave-on products. Clinical experience and patch-test data generally show low irritancy, but as a botanical extract it carries a small, non-zero risk of irritation or allergy from residual plant proteins/impurities—particularly in eczema-prone or highly reactive patients—so it is not scored as fully inert. Safety Notes: In mass-market leave-on lotions, toners, and cleansers, Althaea officinalis (marshmallow) root extract is commonly used as a soothing botanical at very low levels (often around 0.001–0.1%), reflecting typical supplier-recommended use rates for standardized extracts and blends. Higher-end “herbal/soothing” serums, barrier creams, and mask products marketed around mucilage/comfort benefits can use it at 1–5% as the neat extract (or equivalent in a solvent carrier), which is near the upper end seen in OTC products due to viscosity, odor/color, and stability constraints; rinse-off formulas tend to sit toward the lower end while leave-on soothing products trend higher. There is no specific FDA/EU maximum for this INCI beyond general cosmetic safety, so the observed market ceiling is driven primarily by formulation practicality and supplier specifications.

Aluminum Hydroxide

Aluminum hydroxide is primarily used as an opacifier/anti-caking agent or as a coating/buffering component for pigments and UV filters, typically at low percentages in leave-on products. Clinical experience and patch-test data suggest it is generally well tolerated with low inherent irritancy, but it is not completely inert and can contribute to mild irritation in highly reactive or compromised skin, especially with occlusion or when part of complex formulas. For patient safety in severe sensitivity/eczema populations, it warrants a very gentle (but not zero-risk) score. Safety Notes: In commercial skincare, aluminum hydroxide is most often used at very low levels (~0.05–0.5%) as an opacifier/viscosity aid or pigment/lake/UV-filter coating and dispersion aid in lotions, cleansers, and makeup-adjacent skin products. Higher levels are seen in mineral sunscreen systems and tinted sunscreens where aluminum hydroxide-treated TiO2/ZnO and related coated pigments contribute materially to the formula, and in some clay/mineral-rich masks and body products, reaching the low-to-mid teens on an as-supplied basis. This range reflects leave-on and rinse-off products available OTC; concentrations are typically constrained by texture/whitening, stability, and regulatory labeling rather than a specific global maximum for aluminum hydroxide itself.

Aluminum/Magnesium Hydroxide Stearate

Aluminum/Magnesium Hydroxide Stearate is primarily an opacifier/thickener and slip agent used at low levels in powders and creams, and it is generally considered inert with low reactivity on intact skin. Clinical experience and patch testing trends suggest irritation is uncommon, but in eczema-prone or heavily compromised barriers, particulate/metal-soap residues can occasionally contribute to dryness or stinging, so it is best rated as very gentle rather than completely inert for high-sensitivity populations. Safety Notes: Aluminum/Magnesium Hydroxide Stearate is used mainly as a suspending/anti-caking and texture-modifying agent in emulsions and anhydrous systems; in many mainstream leave-on lotions, sunscreens, and color cosmetics it appears at very low levels (~0.05–0.5%) to stabilize pigments/UV filters and improve slip. Higher consumer-available levels (typically ~2–8%) are seen in high-structure sticks/compacts and heavy pigment or mineral UV filter dispersions where it functions as a key gellant/suspending aid; above this, products generally become overly waxy/draggy and are uncommon in OTC skincare. It is not subject to a specific EU/FDA maximum like aluminum salts used as antiperspirant actives, so observed limits are largely driven by sensorial and stability constraints rather than regulation.

Aluminum Silicate

Aluminum silicate is an inert mineral clay/bulking and absorbent agent typically used at low-to-moderate percentages in cosmetics, and it is generally well-tolerated on skin with minimal chemical reactivity. Clinical experience and patch-test data suggest true irritant or allergic reactions are uncommon, but clay/mineral particulates can cause mild dryness or mechanical irritation in very reactive or eczematous skin, especially with frequent use or rubbing. Given that small but real sensitivity/dryness risk in compromised skin exists, it is best categorized as very gentle rather than completely inert. Safety Notes: In commercial skincare, aluminum silicate (commonly present as kaolin/bentonite-type clays or as a rheology/absorbent mineral) appears at low levels (~0.05–1%) as a suspending/thickening and oil-control aid in lotions, sunscreens, and cleansers. Mid-to-high levels (~5–20%) are typical in rinse-off masks and scrubs for absorbency and texture. The highest consumer-available levels (~25–35%) occur in clay-heavy powder masks and concentrated wash-off mud/clay masks where the mineral phase is a primary structuring/absorbing component; these are generally rinse-off rather than leave-on due to dryness/feel and slip constraints.

Aluminum Starch Octenylsuccinate

Aluminum Starch Octenylsuccinate is a modified starch absorbent/mattifier used in leave-on cosmetics (often ~1–10%) to reduce oiliness and improve texture, and it is generally considered low-irritant in patch testing because it is largely inert and not pH-active. The main risk is mechanical dryness or frictional irritation in very compromised or eczematous skin (especially with frequent use in powders), but true chemical irritation or sensitization is uncommon. Given sensitive-skin safety priorities, it fits best as very gentle rather than completely inert. Safety Notes: In commercial leave-on skincare and color cosmetics, Aluminum Starch Octenylsuccinate commonly appears at low levels (~0.1–1%) as a slip/texture aid and oil-absorption booster in lotions, sunscreens, and primers, with some rinse-off cleansers also using similar low single-digit levels for sensorial benefits. High-strength OTC consumer products marketed for strong mattifying, blurring, or dry-touch finishing (e.g., face powders, oil-control primers, and some mineral/soft-matte sunscreens) can push starch-based absorbents into the mid-to-high teens and up to ~25% in powder-heavy systems. No specific FDA/EU maximum limit applies for this ingredient in cosmetics; practical upper bounds are driven by aesthetics (drag/chalkiness) and stability rather than regulation.

Aluminum Stearate

Aluminum stearate is a fatty-acid metal salt used mainly as a thickener/anti-caking agent in powders and some topical formulations, typically at low concentrations (often ~0.5–5%). It is generally considered low-irritant and not a common sensitizer in patch-testing, but as an insoluble particulate it can contribute to mild mechanical/occlusive irritation in highly reactive or eczematous skin, especially with repeated leave-on exposure. Given sensitive-skin safety priorities, I rate it as gentle rather than inert. Safety Notes: In commercial skincare, aluminum stearate is typically used as a low-level suspending agent/viscosity modifier and opacifier in creams, lotions, sunscreens, and some cleansers, where it is often present around 0.05–1%. Higher consumer-available levels are observed in very waxy anhydrous systems (balms, sticks, barrier ointments, some makeup-adjacent skincare) where it functions as a gellant/structurant and can reach roughly 3–8% depending on the oil/wax load and desired payoff. It is more commonly found at higher percentages in leave-on anhydrous formats than in rinse-off products, and no specific EU/FDA cosmetic concentration limit is generally set beyond overall safety substantiation and impurity control.

Aluminum Sulfate

Aluminum sulfate is an astringent/acidic inorganic salt used as a coagulant or styptic; in topical exposure it can lower local pH and denature proteins, making stinging and irritant contact dermatitis more likely, especially on compromised or eczematous skin. Patch testing and clinical experience show it can be irritating (and occasionally problematic when skin barrier is impaired), and its risk increases in leave-on products or higher-concentration/low-pH settings. Given the significant irritation potential in sensitive populations and the likelihood of stinging on broken skin, it warrants a significant irritancy score. Safety Notes: In consumer skincare, aluminum sulfate is most often encountered at very low levels as an astringent/pH-adjuster in toners, aftershaves, and some rinse-off cleansers (commonly around 0.05–1%). The upper end reflects consumer-available high-astringency products such as styptic pencils and alum/“astringent stone” style preparations or very concentrated astringent liquids, where aluminum sulfate can be present in the ~10–20% range (higher levels are generally impractical due to irritation and solubility/stability constraints in typical leave-on skincare).

Amaranthus Caudatus Seed Extract

Amaranthus caudatus (amaranth) seed extract is typically used at low concentrations as an antioxidant/soothing, skin-conditioning botanical, and available safety/patch-test data for amaranth-derived cosmetic ingredients suggests a low rate of irritant reactions. However, as a plant extract containing multiple bioactive compounds, it carries a non-zero risk of irritation or allergy in highly reactive or eczematous skin, especially when layered with other actives. Scoring it as very gentle (0.2) reflects generally good tolerability while acknowledging rare but clinically relevant sensitivity potential. Safety Notes: In commercial skincare, Amaranthus caudatus seed extract is most often used as a minor “botanical/antioxidant/soothing” component in complex blends, where finished-product use levels commonly land around 0.001–0.1% (especially in leave-on serums/creams listing it mid-to-late INCI). Higher-strength consumer products marketed around amaranth-derived actives (e.g., antioxidant/peptide-like or barrier-support positioning) can reach ~1–5% finished-product inclusion when the extract is a primary featured ingredient; above this is uncommon due to cost, sensory impact, and variability of extract solids. Rinse-off products typically sit at the low end because brief contact time reduces the incentive for high loading.

Amber Powder

Amber powder is a particulate botanical/mineral-like additive used mainly for marketing, mild exfoliation, or sensory effects at low concentrations, but it lacks robust clinical irritancy data supporting true inertness. As an insoluble powder, the main risk is mechanical irritation (micro-abrasion/friction) and barrier aggravation in eczema-prone or compromised skin, with occasional contact sensitivity possible due to natural resin contaminants. Given the uncertainty in purity and the avoidable physical irritancy potential in sensitive populations, a mild risk score is the safer clinically-aligned assessment. Safety Notes: In mass-market leave-on skincare, amber powder is most often a minor “botanical/mineral” claim ingredient used at trace levels (typically ~0.001–0.05%) to support marketing and avoid texture/color issues. In exfoliating masks, scrubs, and some “amber” soaps/powdered cleansers available OTC, it is used as a functional particulate at higher loadings, commonly ~0.5–3% and observed up to about 5% in high-grit rinse-off or mask formats; higher levels become challenging due to abrasiveness, opacity, sedimentation, and sensory grit. No specific FDA/EU cosmetic concentration limit is established for amber powder itself, so market use is primarily constrained by safety/sensory performance and particulate handling rather than regulation.

Amino Esters-1

Amino Esters-1 is typically used as a conditioning/surfactant-like ingredient in cleansers or emulsions, and these amphiphilic compounds can disrupt barrier lipids at functional use levels (often around ~0.5–5%), especially with repeated exposure. While not in the same irritancy class as strong acids, retinoids, or oxidizing agents, this category has enough documented stinging/erythema potential in reactive or eczematous skin that I rate it as mild rather than “gentle,” particularly in leave-on or multi-step routines. Safety Notes: Amino Esters-1 is primarily encountered in commercial skincare as a minor functional additive (typically conditioning/skin-feel or auxiliary emulsifier-type use), where it is often dosed at trace-to-low levels around 0.01–0.3% in leave-on creams/lotions and some rinse-off cleansers. Higher-strength consumer-available formulations (usually leave-on serums/creams positioned for enhanced sensory/conditioning benefits) can reach ~1–2%, which is near the practical upper end observed before formula aesthetics and compatibility constraints (odor, tack, phase stability, interaction with anionics) become limiting.

Aminomethyl Propanediol

Aminomethyl propanediol is primarily a pH adjuster/buffering agent used at low concentrations (typically well under 1%) to neutralize acids and stabilize formulations. Patch-test and clinical experience suggest low inherent irritation at these use levels, but because it is alkaline and directly influences final product pH, stinging can occur in compromised barriers or when paired with acids. Overall it is generally well-tolerated, yet not completely inert, so I score it as gentle rather than very gentle. Safety Notes: Aminomethyl propanediol is primarily used as a pH adjuster/buffer, so in many leave-on lotions/serums and rinse-off cleansers it appears at low, utility levels around ~0.05–0.5% (often used alongside carbomer/acrylates systems and neutralizing acids). Higher-strength consumer products such as strong AHA/BHA peel solutions, exfoliating toners, and other low-pH actives can push neutralizer demand upward, with observed OTC formulations reaching roughly 1–5% to achieve target pH and viscosity. There is no specific EU/FDA maximum for this ingredient in cosmetics, so the upper end is driven by formulation/pH needs and sensory limits rather than a formal regulatory cap.

Aminomethyl Propanol

Aminomethyl propanol is primarily a pH adjuster/neutralizer (commonly ~0.1–1%) used to raise pH in formulas; at typical leave-on levels it is usually tolerated but can sting on compromised or inflamed skin due to its alkalinity and local pH shift. Patch testing and clinical experience show low overall reactivity, yet it can trigger mild irritation (burning/erythema) in highly sensitive populations, especially when used alongside other actives or on barrier-impaired eczema skin. Given the need to avoid underestimating risk in reactive patients, this fits a mild irritancy profile rather than “gentle.” Safety Notes: Aminomethyl propanol (AMP) is primarily used as a pH adjuster/neutralizer (e.g., for carbomer/acrylates gels) and is commonly present at low levels around 0.05–0.3% in many leave-on lotions/serums and rinse-off cleansers where only minor pH correction is needed. Higher consumer-available levels are observed in strongly neutralized gel/cream systems (including some high-hold styling gels and certain acid-containing skincare gels) where more base is required, reaching about 1–2.5% in OTC products; above this is uncommon due to potential for elevated pH/irritation and formulation sensorial limits rather than a specific global cosmetic concentration cap.

Aminopropyl Ascorbyl Phosphate

Aminopropyl Ascorbyl Phosphate is a stabilized vitamin C derivative used for brightening/antioxidant support, typically at low percentages and formulated closer to skin-friendly pH than pure ascorbic acid. Available tolerability data and real-world use suggest it is generally well-tolerated, but as a bioactive ascorbate derivative it can still sting or provoke reactivity in compromised barriers (e.g., eczema flares), especially when layered with other actives. Given that sensitive-skin irritation is possible but not common at typical use levels, it fits a gentle-but-not-inert profile. Safety Notes: In commercial skincare, Aminopropyl Ascorbyl Phosphate is most often used in leave-on serums/lotions as a stabilized vitamin C derivative at low inclusion levels (~0.05–0.5%) for general antioxidant/brightening claims, with some products listing it mid-deck as a supporting active around 1–2%. The highest consumer-available formulas observed position it as the primary vitamin C derivative in water-based serums and treatment creams, typically topping out around ~3–5% due to practical limits from solubility, cost, and stability/ionic compatibility considerations. Rinse-off products tend to sit at the low end of the range because of short contact time, while high-end leave-on treatments occupy the upper end.

Aminopropyl Triethoxysilane

Aminopropyl triethoxysilane is a reactive silane coupling agent used at very low levels to improve adhesion/film formation, but it can hydrolyze to yield alkaline/amine-containing species and ethanol, which increases stinging and irritancy risk on compromised skin. Safety data for silanes show potential for skin and eye irritation, and sensitization is not impossible in reactive individuals. Given its reactivity and limited “leave-on facial” tolerance history compared with inert silicones, I score it as a notable irritant where patch testing is prudent for eczema-prone patients. Safety Notes: Aminopropyl triethoxysilane is used primarily as a silane coupling/adhesion-promoting agent in silicone-containing skincare and cosmetic systems, so in mainstream leave-on and rinse-off consumer products it is typically present at trace-to-low levels (often ~0.001–0.1%) to improve film formation, rub resistance, and pigment/filler binding. High-strength, consumer-available “bonding/repair” or specialty primer-type formulations (especially those marketed for enhanced wear/adhesion) can push total silane levels into the low percent range, with observed upper-end use around ~1–2% before odor, irritation potential from aminosilanes, and hydrolysis/stability constraints become limiting. This range excludes professional-only surface-treatment primers and industrial silane treatments, which can be far higher than what is typically sold OTC as skincare/cosmetics.

Ammonium Acryloyldimethyltaurate/VP Copolymer

MVP Approved - Ammonium Acryloyldimethyltaurate/VP Copolymer is a synthetic polymer primarily used as a film-forming, thickening, and emulsion-stabilizing agent in skincare formulations, with a low potential for irritation.

Ammonium Chloride

Ammonium chloride is primarily a pH adjuster/viscosity modifier and is typically used at low concentrations, but as an inorganic salt it can be stinging and irritating on compromised skin due to osmotic and pH-related effects. Patch testing and clinical experience show it can provoke irritation (more than true “gentle” excipients), particularly on eczematous, barrier-impaired, or freshly shaved/post-procedure skin. Given the sensitive-skin risk profile and the need for patch testing in reactive individuals, it warrants a moderate irritancy score. Safety Notes: In consumer skincare, ammonium chloride is most often used at very low levels (~0.05–1%) as a pH adjuster/buffer or viscosity modifier in cleansers, shampoos/body washes, and some creams/lotions, where it functions primarily as an inorganic salt rather than a headline active. The highest OTC consumer-available levels are observed in specialized rinse-off products (notably bath/foot soaks and certain cleansing systems where it acts as a strong electrolyte/processing aid), reaching roughly 10–15%; such high levels are uncommon in leave-on products due to irritation potential and sensory constraints.

Ammonium Glycyrrhizate

Ammonium glycyrrhizate is a licorice-derived anti-inflammatory/soothing agent typically used at low concentrations (about 0.1–1%) to reduce redness and discomfort, and it is generally well tolerated in sensitive-skin formulas. Clinical and post-market experience suggest a low rate of irritation, but as a botanical-derived salt it can still trigger occasional reactivity in highly sensitized or eczema-prone individuals, so it cannot be considered inert. Safety Notes: In commercial skincare, ammonium glycyrrhizate is commonly used as a soothing/anti-redness agent at low levels around 0.01–0.1% in leave-on toners, emulsions, and sensitive-skin moisturizers (often as a supporting anti-irritant alongside panthenol/allantoin). Higher-strength consumer products—typically targeted brightening/spot serums, post-procedure calming gels, or concentrated ampoules—are observed up to ~1–2% where solubility, tack/feel, and potential irritation from highly active bases become practical formulation limits. Rinse-off cleansers and masks usually sit toward the lower end because contact time is short and high levels can impact foam and sensorial profile.

Ammonium Hydroxide

Ammonium hydroxide is a strongly alkaline pH adjuster/hair dye component that can be corrosive and is a well-documented eye/skin irritant, with irritation risk rising sharply with concentration and contact time. Even at lower cosmetic-use levels, products relying on it to raise pH (e.g., permanent hair color, depilatories) are associated with burning and barrier disruption, and compromised or eczematous skin is particularly vulnerable. Given its intrinsic alkalinity and clinical irritancy profile, I score it very high for patient safety. Safety Notes: In skincare-adjacent cosmetic products, ammonium hydroxide is most often used as a pH adjuster/alkalizing agent and is typically present at very low levels (around ~0.05–0.3%) in rinse-off cleansers/soaps and some leave-on systems where only small additions are needed to neutralize acidic components. The highest consumer-available levels observed are in strongly alkaline, rinse-off depilatory/bleaching/relaxer-type formulations and certain alkaline peels/masks sold OTC, where ammonium hydroxide can reach about ~1–2% to drive high pH and performance; higher levels are uncommon in OTC facial leave-on products due to irritation and safety constraints.

Ammonium Laureth Sulfate

Ammonium Laureth Sulfate is an anionic surfactant/foaming cleanser typically used around ~5–15% in rinse-off formulas, where it can disrupt stratum corneum lipids and increase transepidermal water loss. Clinical and patch-test data across surfactants consistently show sulfated ethoxylates can cause irritant contact dermatitis, with higher risk in atopic/eczema-prone and barrier-impaired skin, especially with frequent use or prolonged contact. While many people tolerate it in well-formulated rinse-off products, its mechanism and real-world exposure make it a significant irritant risk in sensitive populations. Safety Notes: Ammonium Laureth Sulfate is predominantly used in rinse-off cleansers (shampoos, body washes, facial washes), where very mild/sulfate-reduced formulas and baby/sensitive washes often include it around ~0.5–3% active as a secondary surfactant or to boost foam. Mainstream mass-market shampoos and body washes commonly sit in the ~5–15% active range, while high-foam clarifying shampoos and concentrated surfactant bases sold to consumers (often supplied as ~25–70% active ALS solutions) can yield finished-product actives in the ~20–35% range; it is rarely used in leave-on products due to irritation potential.

Ammonium Lauryl Sulfate

Ammonium Lauryl Sulfate is an anionic surfactant used in cleansers and shampoos (often a few percent up to ~10%+) and is well-documented to be more irritating than milder surfactants due to lipid/protein disruption of the stratum corneum. Human patch and repeated-wash exposure data show it can cause stinging, dryness, and irritant contact dermatitis—risk amplified in eczema, compromised barriers, and when combined with other actives or frequent cleansing. For sensitive-skin safety, it merits a high score because irritation is common and predictable at typical use concentrations. Safety Notes: In real-world consumer rinse-off products (cleansers, shampoos, body washes), ammonium lauryl sulfate is often used at low levels (~0.5–3%) as a secondary/anionic co-surfactant or foam booster in milder sulfate-containing systems and in sensitive-skin washes where total surfactant is kept low. At the high end, mass-market and “clarifying/deep clean” shampoos and strong foaming washes can reach ~15–25% ALS as supplied (typically corresponding to roughly ~10–18% active matter depending on the raw material strength), with higher use generally constrained by irritation potential and viscosity/phase behavior; it is rarely used in leave-on products and, if present there, is typically at trace/very low levels.