Skincare Ingredients

Chamomilla Recutita Extract

MVP Approved - Chamomilla Recutita Extract is a botanical ingredient prized for its soothing, anti-inflammatory properties and is generally well-tolerated in skincare formulations.

Chamomilla Recutita Flower Extract

Chamomilla recutita (matricaria) flower extract is used primarily for soothing/anti-inflammatory effects, typically at low concentrations, and is often well-tolerated in general populations. However, it contains sesquiterpene lactones and other botanically derived constituents that can trigger allergic contact dermatitis—especially in atopic patients or those sensitized to Asteraceae/Compositae plants—and this sensitization risk warrants a mild (not “very gentle”) irritancy rating for safety. Safety Notes: In mass-market leave-on products (lotions, toners, cleansers) chamomile extract is frequently used as a soothing claim ingredient at very low levels around 0.01–0.1%, especially when supplied as a diluted glycerin/propylene glycol extract. Mid-range use in calming serums and creams is commonly ~0.2–2% depending on extract strength, while consumer-available ‘high-chamomile’ botanical formulas and some single-extract serums can reach ~5–10% (typically still limited by extract solvent system, color/odor, and stability). Rinse-off products often sit toward the lower end because of brief contact time, but high botanical-load wash products can still approach the upper range when formulated with concentrated extracts.

Charcoal Powder

Charcoal powder (activated carbon) is used as an insoluble absorbent/clarifying agent in cleansers and masks, typically a low-percentage particulate that mainly poses mechanical rather than chemical irritation risk. Clinical experience and patch-test data generally show low inherent irritancy, but in sensitive or eczematous skin the gritty particles and strong oil-adsorption can disrupt barrier lipids and trigger stinging, dryness, or flare-ups—especially with frequent use or in leave-on/gritty formulas. Given these predictable reactions in compromised skin despite the ingredient’s “gentle” marketing, I score it as mild. Safety Notes: In commercial skincare, charcoal powder is often used at very low levels (~0.05–0.5%) mainly for marketing color/“detox” positioning in leave-on products and some cleansers where higher load can feel gritty or destabilize emulsions. Most rinse-off cleansers and masks fall around ~0.5–3% for visible black color and mild adsorptive claims, while the highest-strength consumer products (especially wash-off masks, scrubs, and some bar/solid cleansers) can reach ~5–10% to deliver strong visual impact and oil-absorbing feel. Levels above this are uncommon in mainstream OTC skincare due to texture, staining, and sensorial/processing constraints, and charcoal is typically used higher in rinse-off than in leave-on formats.

Chenopodium Quinoa Seed Oil

Chenopodium Quinoa Seed Oil is an emollient plant oil typically used at low-to-moderate levels in moisturizers and serums to support barrier function and reduce transepidermal water loss. Like most non-fragrant carrier oils it is generally well-tolerated, but botanical lipids can still trigger irritation or contact allergy in a small subset of highly reactive or eczema-prone patients (especially on compromised skin), so it is not scored as inert. Safety Notes: In commercial skincare, Chenopodium Quinoa Seed Oil is commonly used at very low levels (around 0.01–0.5%) as a supporting emollient/marketing oil in complex leave-on emulsions and serums, and at ~1–10% in richer creams, balms, and hair/skin oils blends. The highest observed consumer-available strength is 100% in single-ingredient “pure quinoa seed oil” products and near-neat anhydrous blends (typically 30–90%) sold as facial/body oils; rinse-off cleansers and washes usually sit at the low end due to rinse-off deposition and surfactant system constraints.

Chlorella Vulgaris Extract

Chlorella Vulgaris Extract is primarily used as an antioxidant/skin-conditioning botanical, typically at low concentrations, and is generally well tolerated in routine cosmetic use. However, as a complex algae-derived mixture (proteins, polysaccharides, pigments), it has a non-trivial risk of irritation or allergy in highly reactive or eczematous patients compared with inert humectants, especially with leave-on exposure and cumulative use alongside other actives. Given this sensitization potential seen with some botanical extracts in patch testing populations, I score it as mild rather than “gentle.” Safety Notes: In mass-market leave-on products (creams/lotions/serums), Chlorella Vulgaris Extract is often used at very low levels (around 0.0005–0.05%) as part of multi-botanical blends or pre-preserved glycerin/water extracts where the listed INCI represents a dilute extract. More performance-positioned anti-aging/firming leave-on products commonly use ~0.1–2% depending on extract potency and solvent system, while a small number of consumer-available “single-algae/high-load” ampoules, masks, and concentrates push the active extract phase to the upper end around 3–5% (typically for hydroglycolic extracts rather than dry powder). Rinse-off products generally sit in the lower half of the range due to brief contact time, though high-load wash-off masks can reach the upper end when marketed around algae content.

Chlorhexidine Digluconate

Chlorhexidine digluconate is a broad-spectrum antiseptic typically used around 0.05–4% (higher in surgical/medical prep), and it is well-documented to cause irritant contact dermatitis and, in a subset of patients, allergic contact reactions. In eczema-prone or barrier-impaired skin, stinging/burning and dermatitis are more likely, and cumulative exposure from repeated cleansing can amplify irritation. Given its active antimicrobial nature and clinically significant irritation/sensitization potential, a significant-risk score is warranted. Safety Notes: In consumer skin-care and personal-care products, chlorhexidine digluconate is most often encountered at very low levels (~0.01–0.05%) as an antimicrobial/anti-odor or preservative-support ingredient in rinse-off cleansers and some leave-on hygiene products. The highest widely consumer-available OTC skin antiseptic/hygiene and acne/blemish-type products typically top out around 0.2% chlorhexidine digluconate (higher concentrations are generally positioned as medicinal antiseptics or professional-use preparations rather than cosmetic skincare). Leave-on use is more constrained by irritation/sensitization potential, so the upper end is more commonly seen in rinse-off or short-contact formats.

Chlorophene

Chlorophene is an antimicrobial preservative/antiseptic used at low concentrations but has a well-documented history of causing irritant contact dermatitis and, in some patients, allergic contact dermatitis on patch testing. Because it can be problematic on compromised barriers (e.g., eczema) and irritation risk increases with leave-on exposure and cumulative use alongside other irritants, it warrants a significant irritancy rating for sensitive-skin safety. Safety Notes: In contemporary OTC cosmetics, chlorophene is encountered primarily as an antimicrobial preservative/deodorant active, with low-end use around ~0.05% in leave-on lotions/creams where it functions as part of a broader preservation system. The highest consumer-available levels are typically ~0.2–0.3% in deodorant-type or antimicrobial personal-care products (and some rinse-off cleansers), reflecting both efficacy needs and regulatory/compliance constraints that have limited broader/higher usage in many markets.

Chlorophyllin-Copper Complex

Chlorophyllin-copper complex is a water-soluble chlorophyll derivative used mainly as a colorant/antioxidant and is typically included at low concentrations (often well under 1%), where it is generally well tolerated in patch-testing and consumer use. However, as a botanical-derived pigment complex it can still trigger irritation or allergy in a small subset of highly reactive or eczema-prone patients (and can be more stinging on compromised barriers), so I rate it as gentle but not “exceptionally gentle.” Safety Notes: In commercial skincare, chlorophyllin-copper complex is most often used as a colorant/marketing active in low-dose deodorizing/“anti-odor” or soothing formulas, commonly appearing in leave-on products at trace levels around 0.0001–0.01% (especially when supplied as a dilute solution or carried in a blend). Higher-strength consumer-available products (notably deodorizing masks, acne/clarifying gels, and some specialty “chlorophyll” serums) can reach roughly 0.1–0.5% active, with the upper end constrained by color intensity, staining risk, odor, and stability/compatibility in the finished base; rinse-off products typically sit toward the lower-mid end because short contact time reduces the need for very high loading.

Chloroxylenol

Chloroxylenol (PCMX) is an antimicrobial commonly used in antiseptic washes/soaps (often ~0.5–4%), where it can disrupt the skin barrier and has documented irritant contact dermatitis risk, especially with frequent or prolonged exposure. While true allergy is less common than irritation, compromised-skin patients (e.g., eczema) are more likely to sting, burn, or flare. Given its intended biocidal activity at functional concentrations and real-world leave-on transfer/residue from cleansers, it warrants a significant irritation score. Safety Notes: In consumer skin-cleansing antiseptics, chloroxylenol (PCMX) is found at very low levels (~0.05–0.1%) in mild antimicrobial hand/body washes and deodorizing soaps, where it functions mainly as an antibacterial deodorant/cleanser active. The highest widely marketed OTC strengths are concentrated antiseptic liquids and surgical scrub-style washes sold to the general public, typically ~4.8% PCMX (often labeled ~4.8% w/v), used primarily as rinse-off products due to irritation and sensitization potential at higher levels. Leave-on skin products containing PCMX are uncommon and, when present, are generally at the low end of this range.

Chlorphenesin

MVP Approved - Chlorphenesin is a synthetic preservative widely used in cosmetic formulations to prevent microbial growth, with a low incidence of irritation when used at approved concentrations.

Cholesterol

MVP Approved - Cholesterol is a key lipid used in skincare to reinforce the skin barrier and enhance hydration, and it is consistently recognized as having low irritancy.

Chondrus Crispus

Chondrus crispus (Irish moss) is primarily a film-forming thickener/skin-conditioning seaweed extract used at low percentages, and in clinical experience it is generally well tolerated with low irritancy potential. However, as a botanical/marine-derived extract it can contain trace proteins/iodine and variable constituents that occasionally trigger stinging or dermatitis in highly reactive or eczema-prone patients, so it is not truly inert. For patient safety in severe sensitivity populations, I score it as very gentle rather than exceptionally gentle. Safety Notes: Chondrus crispus (Irish moss/seaweed extract, often supplying carrageenan-type polysaccharides) is commonly used at very low levels (~0.05–0.5%) in leave-on lotions/serums and rinse-off cleansers primarily for viscosity/film-forming and skin-feel benefits. In higher-solids gel creams, masks, and “seaweed” treatment products marketed to consumers, total Chondrus-derived material can reach ~2–5% (especially when used as a primary gelling/texture and sensory component), with higher levels generally limited by tackiness, odor/color, and stability constraints rather than regulation.

Chondrus Crispus Powder

Chondrus crispus (Irish moss) powder is primarily a film-forming thickener/skin-conditioning seaweed ingredient used at low levels in cosmetics, and it is generally well tolerated without the inherent irritancy profile of acids, retinoids, or surfactants. However, as an unrefined botanical/marine powder, it can contain a broader mix of naturally occurring proteins and trace constituents that increase the chance of irritation or sensitization in highly reactive or eczema-prone patients compared with purified gums/extracts. Given this low-but-nonzero risk in compromised skin, it best fits a gentle (not inert) score. Safety Notes: In commercial skincare, Chondrus Crispus Powder (Irish moss/seaweed powder) is often used at trace levels (~0.01–0.1%) in leave-on lotions/serums primarily for marketing/skin-conditioning claims or to support a natural positioning. More functional use as a viscosity/texture aid and water-binding seaweed solid is typically ~0.2–2% in masks and richer creams, while the upper end (~3–5%) is seen in consumer-available, high-solids wash-off masks, bath/soap bars, and exfoliating or clay/seaweed powder blends where higher loading is feasible without unacceptable grittiness or instability.

Chromium Hydroxide Green

Chromium Hydroxide Green is an insoluble inorganic pigment used to color cosmetics at low concentrations, and as a particulate colorant it is generally associated with low irritancy in most users. However, pigments can still cause mechanical/occlusive irritation on compromised skin and there is a small but real risk of sensitization or irritation in chromium-reactive individuals, so it cannot be treated as inert for highly sensitive or eczematous patients. Safety Notes: Chromium Hydroxide Green is used primarily as a colorant (CI 77289) in consumer cosmetics; at the low end it appears as a trace pigment in tinted skincare (e.g., green-correcting primers, tinted sunscreens, concealers) where only very small amounts are needed to shift tone. At the high end, it can be a major component of the pigment blend in high-pigment color cosmetics (cream/stick concealers, face paints, theatrical body makeup) sold OTC, where total inorganic pigment loading can reach the low-to-mid teens and this pigment can represent a large fraction of that load. Use levels are generally similar for leave-on vs rinse-off when used purely for color, and are constrained mainly by shade requirements and dispersion/texture rather than a specific global percentage cap.

Chromium Oxide Greens

Chromium Oxide Greens (CI 77288) is an insoluble inorganic pigment used primarily as a colorant in leave-on cosmetics, typically at low percentages, and it is generally non-reactive and well-tolerated. Clinical patch-testing experience suggests a low rate of irritation, but particulate pigments can still trigger mild mechanical/occlusive irritation or rare individual sensitivity, especially on compromised eczematous skin. Given the sensitive-skin safety focus, I rate it as very gentle rather than fully inert. Safety Notes: In commercial color cosmetics and some tinted skincare (leave-on), chromium oxide greens is typically used at very low levels (~0.01–0.5%) to adjust undertone or mute redness within mixed pigment systems. In high-pigment consumer products (e.g., pressed/powder eye products, green corrector creams/sticks, camouflage makeup), total pigment loads can be high and chromium oxide greens has been observed up to ~10–25% where it is a primary colorant. Use is primarily leave-on; rinse-off products rarely include it and, when they do, it is usually only trace-level for color.

Chrysanthellum Indicum Extract

Chrysanthellum indicum extract is a botanical used at low concentrations (typically <1–3%) for soothing/anti-redness and microcirculation support, and it is generally well-tolerated in standard cosmetic patch testing. However, as a multi-component plant extract (often containing flavonoids/saponins), it carries a small but real risk of irritant or allergic contact dermatitis in eczema-prone or highly reactive patients, so it cannot be scored as very gentle/inert. Safety Notes: In commercial skincare, Chrysanthellum indicum extract is most often used as a microcirculation/soothing botanical in leave-on serums and eye/anti-redness products, commonly appearing at low “label-support” levels around 0.01–0.1% depending on extract potency and supplier standardization. More performance-driven consumer products (e.g., vascular-look, under-eye, anti-redness concentrates) typically use ~0.5–2%, with the highest observed OTC levels around ~3% for formulas built around this extract (often with glycerin/propylene glycol carrier extracts and solubility/odor-color constraints). Rinse-off products generally sit at the low end because of short contact time and cost/claims strategy.

Chrysanthemum Parthenium Extract

Chrysanthemum parthenium (feverfew) extract is used as a soothing botanical at low concentrations, but Asteraceae plant extracts can contain sesquiterpene lactones (e.g., parthenolide) that are well-documented triggers of allergic contact dermatitis in sensitized and eczema-prone patients. Even when “parthenolide-free” is claimed, batch variability and cross-reactivity with other Compositae allergens make reactions plausible, so I score it as a moderate irritant/allergen with patch testing advised for sensitive skin. Safety Notes: In commercial skincare, Chrysanthemum parthenium (feverfew) extract is often used at very low levels (around 0.001–0.05%) as a soothing/antioxidant botanical in leave-on creams, serums, and toners, especially when the extract is standardized for key markers. Higher-strength consumer-available products (typically leave-on calming serums/masks and some botanical-heavy creams) can reach ~1–5% when the extract is supplied as a dilute glycerin/propylene glycol/water carrier and used as a featured active botanical. Concentrations above this are uncommon in OTC due to sensitization/allergen management (e.g., parthenolide control) and stability/odor/color constraints; rinse-off products tend to sit at the lower end because of reduced deposition time.

Chrysanthemum Parthenium Flower Extract

Chrysanthemum parthenium (feverfew) flower extract is used in low concentrations as a soothing/antioxidant botanical, but it is part of the Asteraceae/Compositae family and contains sesquiterpene lactones (e.g., parthenolide) associated with allergic contact dermatitis in patch testing and real-world sensitization. Even when processed to reduce parthenolide, batch variability and cross-reactivity (especially in eczema-prone or fragrance/botanical-reactive patients) make irritation/sensitization risk clinically notable. Given the potential for delayed reactions and the high stakes in compromised skin, it should be treated as an active botanical requiring careful introduction and patch testing. Safety Notes: In mass-market and prestige leave-on products (especially serums, moisturizers, and eye creams), Chrysanthemum Parthenium (feverfew) flower extract is commonly included as a soothing/antioxidant botanical at very low levels (often ~0.001–0.05%) as part of a broader botanical complex, which reflects typical supplier-recommended use rates and cost/odor/color constraints. Higher-strength consumer products marketed for redness/“calming” can push standardized feverfew/chrysanthemum extracts into the ~0.5–3% range, with the upper end most often seen in concentrated leave-on serums/ampoules rather than rinse-off cleansers, where levels are generally kept lower due to brief contact time and formula economics.

Chrysin

Chrysin is a flavonoid antioxidant/anti-inflammatory used in low concentrations (typically well under 1%) in soothing or “brightening” formulas, and it is not a known primary irritant like acids or retinoids. However, as a bioactive polyphenol it has documented potential for contact allergy/irritant reactions in a minority of users, and real-world risk increases when combined with other actives or used on compromised eczema-prone skin. Given limited robust clinical irritation datasets in highly sensitive populations, I rate it as mild to reflect occasional sensitivity and the need for patch testing in reactive patients. Safety Notes: In commercial skincare, chrysin is typically used as a minor bioflavonoid active in brightening/anti-dark-circle and anti-glycation/antioxidant complexes, often appearing at very low levels (~0.0005–0.05%) when part of multi-ingredient blends or encapsulated systems where the INCI lists chrysin but the delivered active is small. Higher-strength consumer leave-on serums/eye products that feature chrysin more explicitly are observed up to about 0.5–1.0%, with further increases uncommon due to solubility/formulation limits, color/odor impact, and diminishing practicality in OTC cosmetics; rinse-off use is rarer and generally at the low end because of short contact time.

Ci 75810

CI 75810 is an inorganic colorant/pigment used at low concentrations to tint products, and as an insoluble particulate it is generally low-reactivity on intact skin. However, colorants can still trigger irritation in highly reactive or barrier-impaired skin via mechanical/particulate effects (especially near eyes or on eczematous skin) and occasional impurity-related sensitivity. Given sensitive-skin safety considerations, I rate it as gentle but not inert. Safety Notes: CI 75810 is chlorophyllin-based (green) colorant and in skincare is most often used at trace levels to tint gels, serums, masks, soaps, and cleansing products; in commercial INCI-listed formulas it commonly appears in the ~0.0001–0.05% range where only a slight green hue is needed. The upper end is represented by highly pigmented consumer-available color-correcting/green-tinted products and some deodorant/soap or mask-type formulas where the colorant load can reach low single-digit percentages (often as part of a chlorophyllin/colour blend or dispersion), with ~5% as a practical top-end seen in OTC products due to staining, shade intensity, and stability constraints. No specific EU/FDA concentration limit is typically assigned to this CI beyond general color additive compliance, so market limits are mainly performance and aesthetics-driven (leave-on tends to be lower than rinse-off to reduce staining).

CI 77220

CI 77220 is an inorganic colorant (commonly used as a cosmetic pigment) typically present at low percentages in makeup and tinted skincare, where it functions as an insoluble particulate rather than a reactive active. In clinical use, such mineral pigments are generally well tolerated, but in highly reactive or barrier-impaired skin they can contribute to mild irritation via friction/particle load or contamination/impurities, so it is not scored as fully inert. Overall, the irritation potential is low at typical concentrations, consistent with a 'very gentle' rating while still acknowledging sensitive-skin edge cases. Safety Notes: CI 77220 (Calcium Sulfate) is used as a bulking agent, absorbent, and opacifier in cosmetic products. At the low end (0.01-0.1%), it appears in liquid foundations and serums as a minor opacity modifier. At the high end (15-25%), it's a primary ingredient in powder formulations including face powders, dry shampoos, body powders, and pressed powder compacts where it serves as a major bulking and absorbent component.

CI 77491

CI 77491 (iron oxide red) is an inert mineral pigment used in cosmetics and sunscreens at concentrations typically 1-25%. Clinical patch testing and decades of use data demonstrate exceptionally low irritation potential, as it is chemically stable, non-reactive, and does not penetrate skin. While hypersensitivity is theoretically possible in extremely rare cases, this ingredient has one of the best safety profiles in cosmetic formulation, suitable even for post-procedure and compromised skin barriers. Safety Notes: CI 77491 (red iron oxide) is used at trace levels (~0.0001–0.01%) in lightly tinted skincare, tone-up/anti-redness primers, and some lotions/SPF where it appears near the end of the INCI list. Mid-range use (~0.1–10%) is common across foundations, BB/CC creams, tinted sunscreens and concealers depending on shade depth. The upper end (up to ~35%) is observed in highly pigmented consumer-available color cosmetics such as cream/powder foundations, concealers, and stick products (including some “pure pigment”/camouflage-style makeup); rinse-off products rarely approach these levels because high pigment loads are generally unnecessary and less stable/sensorially acceptable.

CI 77891

CI 77891 is titanium dioxide, an inorganic pigment/UV filter used at variable but often meaningful levels in makeup and mineral sunscreens; it is insoluble and generally biologically inert on intact skin. Clinical experience and patch testing show low irritancy for most users, but in eczema-prone or highly reactive skin it can still cause mild irritation from particulate/friction effects or from contaminated/impure grades, so it is not scored as completely inert. Safety Notes: CI 77891 (titanium dioxide) appears at trace levels (~0.01–0.1%) as an opacifier/whitener in lotions, cleansers, and creams, including some rinse-off products where only minimal whitening is needed. In leave-on color cosmetics and hybrid skincare (tinted moisturizers, foundations, concealers, tone-up/brightening creams), it commonly rises into the several-percent range and can reach ~20–30% in highly pigmented, high-coverage consumer products. While TiO2 can also serve as a UV filter, the highest consumer-available levels are most consistently observed in pigmented makeup and tone-up products rather than standard facial sunscreens.

Cichorium Intybus Root Extract

Cichorium Intybus (chicory) root extract is primarily used as a soothing/humectant or prebiotic-type botanical (often via inulin/fructans) at low concentrations (commonly ~0.1–2%) and is generally well tolerated in leave-on products. However, as a complex plant extract it carries a non-zero risk of irritation or allergic contact dermatitis in highly reactive or eczema-prone individuals, especially when formulations include multiple botanicals. Given the potential for delayed sensitization despite a typically gentle profile, it fits best as a "gentle" ingredient rather than exceptionally gentle/inert. Safety Notes: In commercial skincare, Cichorium intybus (chicory) root extract is often used at trace levels (around 0.0005–0.05%) as part of broader botanical blends or preservative-adjacent “anti-pollution/soothing” complexes in leave-on lotions/serums and some rinse-off cleansers. Standalone or hero-claim barrier/firming/“inulin-rich prebiotic” formulas commonly land around 0.1–1%. High-strength consumer products (especially “prebiotic” serums, masks, or ampouled concentrates using chicory extract/inulin-type concentrates) can reach ~2–5% where texture/solids loading and stability allow; higher levels are uncommon in mass-market leave-on due to tackiness/viscosity and supply form constraints rather than regulatory limits.

Cimicifuga Racemosa Root Extract

Cimicifuga racemosa (black cohosh) root extract is a botanical antioxidant/soothing-type additive typically used at low concentrations, but like many plant extracts it contains multiple bioactive constituents that can trigger irritant reactions in reactive or eczema-prone skin. Human topical safety data are limited compared with well-characterized emollients, and botanical extracts have a meaningful background rate of stinging/dermatitis in sensitive-skin patch testing, especially in compromised barriers. Given the uncertainty and the need to protect highly sensitized patients, I score it as mild rather than gentle. Safety Notes: In commercial skincare, Cimicifuga racemosa (black cohosh) root extract is most often used as a supporting botanical in anti-aging/soothing leave-on creams and serums at very low levels (~0.01–0.1%), consistent with typical supplier-recommended use levels for standardized botanical extracts. Higher-strength consumer products (botanical “active” serums, concentrated ampoules, and some natural/indie formulas using glycerin/propylene glycol extracts or extract blends) can reach ~1–5% while remaining OTC; above this is uncommon due to odor/color impact, solubility/stability constraints, and increased sensitization risk. Rinse-off products generally sit at the low end because of brief contact time, while leave-on products account for the highest observed concentrations.

Cinnamomum Zeylanicum Bark Extract

Cinnamomum zeylanicum (cinnamon) bark extract is a fragrance/botanical extract rich in cinnamaldehyde and related aromatic compounds that are well-documented irritants and can also act as contact allergens in patch testing. Even at the low concentrations typical for cosmetics, it can provoke burning, erythema, and eczema flares in sensitive or barrier-impaired skin, and cumulative exposure in a routine increases risk. Given its known irritant/allergenic profile and the high stakes for eczema-prone patients, it warrants a high irritancy score. Safety Notes: In commercial leave-on skincare, Cinnamomum Zeylanicum (Cinnamon) Bark Extract is most often used as a minor “botanical/antioxidant” component of blends, where it can appear at trace-to-low levels (~0.0005–0.05%), especially in sensitive-skin products due to fragrance-allergen/irritancy concerns. Higher concentrations are seen in consumer-available “warming,” “purifying,” or acne-focused products and some rinse-off masks/cleansers, where it is used more deliberately for sensory effect and can reach ~0.5–2.0% in the finished formula (with rinse-off products generally tolerating the upper end more readily than leave-on). The upper bound reflects observed OTC specialty formulations while staying below levels more typical of essential oil–driven or professional-use products.

Cinnamyl Alcohol

Cinnamyl Alcohol is a fragrance ingredient (EU-listed fragrance allergen) commonly used at low concentrations, but it has well-documented potential to cause allergic contact dermatitis and can also sting/irritate compromised skin. In sensitive populations (eczema, barrier-impaired, post-procedure), even trace fragrance allergens can trigger significant reactions, so I score it as high irritancy risk from both sensitization and cumulative exposure in full routines. Safety Notes: Cinnamyl Alcohol is primarily used as a fragrance component (and EU-declarable fragrance allergen), so it often appears at trace levels in scented skincare where it is present as part of a fragrance compound, with commercial products commonly landing around the low ppm range (~0.0001–0.01%). The highest observed OTC consumer levels are in strongly fragranced leave-on products (e.g., perfumes/body lotions) and some fragranced rinse-off cleansers where the fragrance load is higher; in these cases cinnamyl alcohol can reach roughly 0.1–0.3% depending on the fragrance design. For leave-on products, allergen labeling thresholds in the EU (0.001% leave-on; 0.01% rinse-off) often drive disclosure and tend to keep typical use low, but they do not function as hard maximum limits.

Citral

Citral is a fragrance component (from citrus oils and also used as an isolated aroma chemical) typically present at low concentrations, but it is a well-documented skin sensitizer and can also be irritating, especially on compromised barriers. Patch-test data and clinical experience show a meaningful risk of allergic contact dermatitis in fragrance-sensitive and eczema-prone patients, and irritation risk increases when combined with other fragranced products in a routine. Given the high sensitization potential and the disproportionate harm in reactive populations, it warrants a high irritancy score despite low use levels. Safety Notes: In commercial skincare, citral is most commonly present as a trace-level fragrance constituent of essential oils/perfume and is frequently seen around ~0.00001–0.01% in finished products (especially leave-on creams/serums) where it appears incidentally from botanical extracts or fragrance blends. The upper end is observed in strongly fragranced, consumer-available products (e.g., citrus essential-oil-forward body products, soaps, and some fragrance-mist style skin products), where finished-product citral can reach ~0.1–0.3%, with rinse-off formats more tolerant of higher levels than leave-on due to irritation/sensitization risk. EU allergen labeling requirements apply when citral exceeds 0.001% in leave-on products or 0.01% in rinse-off products, which influences how often very high levels are used in mainstream formulations.

Citrate Buffer

Citrate buffer (typically a citric acid/sodium citrate system) is used at low concentrations to stabilize and adjust product pH, and the salts themselves are generally well-tolerated in patch testing. However, because its purpose is to influence pH, it can sting or exacerbate irritation on compromised barriers (e.g., eczema, post-procedure) if the final formula is even mildly acidic, so it is not completely inert. In routine leave-on and rinse-off products at appropriate pH, it is usually very gentle but still warrants caution in highly reactive skin. Safety Notes: In commercial skincare, citrate buffer systems (typically citric acid with sodium citrate and/or potassium citrate) are often used at low levels (~0.05–0.3%) to fine-tune pH in leave-on creams/serums and cleansers without materially impacting skin feel. Higher total buffer loads are seen in consumer-available high-acid products (AHA/BHA exfoliating toners, peels, and some acne/brightening formulas) where stronger buffering is needed to control pH and stability, commonly ~0.5–2% and occasionally up to ~3% total citrate buffer in OTC products. Rinse-off products may use similar or slightly higher levels than leave-on when neutralizing surfactant systems or stabilizing low-pH formulas, but concentrations above ~3% are uncommon in mainstream OTC due to irritation risk and formula constraints.

Citric acid

MVP Approved - Citric acid is an alpha hydroxy acid (AHA) used for gentle exfoliation, pH balancing, and improving skin texture, though it can cause moderate irritation when used at higher concentrations.