Skincare Ingredients

Methylene Bis-Benzotriazolyl Tetramethylbutylphenol

Methylene Bis-Benzotriazolyl Tetramethylbutylphenol (Tinosorb M) is a photostable, insoluble particulate UV filter typically used around 1–10% in sunscreens and is generally well-tolerated in clinical use, including sensitive-skin populations. Reported irritation and sensitization rates are low, with reactions more often attributable to the overall sunscreen vehicle rather than this filter itself; however, as a particulate dispersed in formulations, it can still provoke mild stinging or irritation in highly reactive or barrier-impaired skin. Given its broad use and low intrinsic reactivity but non-zero risk in compromised skin, it fits best as very gentle rather than inert. Safety Notes: In commercial sunscreens and daily moisturizers with SPF, Methylene Bis-Benzotriazolyl Tetramethylbutylphenol (also known as Tinosorb M) is observed at low levels (~0.1–1%) mainly as a supportive UV filter/photostabilizer in multi-filter systems. High-protection OTC sunscreens marketed in regions where it is permitted (notably EU/UK and many other non-US markets) commonly use ~2–8%, with the highest consumer-available formulas reaching the EU maximum of 10% for leave-on products; it is rarely used in rinse-off products due to particulate dispersion and film-forming requirements.

Methyl Gluceth-20

Methyl Gluceth-20 is a non-ionic humectant/emollient (a methyl glucose ethoxylate) typically used around ~1–10% to improve slip and reduce irritation in formulations. Available safety and patch-test data suggest a very low rate of irritation or sensitization, even in leave-on products, though any ethoxylated surfactant-like material can rarely sting on severely barrier-impaired or post-procedure skin. Given its strong track record but non-zero risk in highly reactive eczema patients, I score it as very gentle rather than inert. Safety Notes: In commercial skincare, Methyl Gluceth-20 is commonly used as a secondary humectant/emollient and sensory modifier, with low-end usage around 0.1–0.5% in rinse-off cleansers and multi-ingredient leave-on formulas where it supports slip and mild moisturization. Typical leave-on lotions/serums often fall in the ~1–5% range, while higher-strength consumer-available moisturizers, after-sun gels, barrier creams, and sensitive-skin soothing products can reach ~10–20% to deliver a stronger humectant feel and improved skin comfort without being prescription-only. It is not specifically restricted by major cosmetics regulations, so the upper end is primarily constrained by formula aesthetics, tackiness, and compatibility with the overall system rather than regulatory limits.

Methyl Gluceth-20 Benzoate

Methyl Gluceth-20 Benzoate is primarily a solubilizer/emollient (a sugar-derived ethoxylated glucoside ester) typically used at low percentages in leave-on products to improve feel and reduce tack. Available safety and patch-test experience with the Methyl Gluceth family suggests low irritancy and low sensitization potential, with rare reactions mainly in highly compromised barriers. Given its non-acidic, non-volatile nature and typical low-use levels, it is best classified as very gentle, while still acknowledging that extreme eczema flares can react to almost any surfactant-like solubilizer. Safety Notes: In commercial leave-on skincare (lotions, serums, moisturizers), Methyl Gluceth-20 Benzoate is most often used as a mild, water-soluble emollient/humectant-adjacent sensorial modifier at low levels (~0.05–0.5%) where it primarily improves slip and reduces tack. Higher-strength consumer-available products (rich moisturizers, barrier creams, and some specialty “hydrating” concentrates) can use it in the ~1–5% range to contribute more noticeably to emolliency and after-feel without destabilizing typical O/W systems. It is less common in rinse-off products, but when present the levels generally remain toward the lower end because short contact time reduces the benefit.

Methyl Glucose Sesquistearate

MVP Approved - Methyl Glucose Sesquistearate is a mild emulsifier used in skincare formulations to stabilize oil‐water mixtures, offering low irritancy and supporting skin hydration with an improved product texture.

Methylglucoside Phosphate

Methylglucoside phosphate is primarily a mild humectant/conditioning ingredient used at low percentages in leave-on and rinse-off products, and it is not an acid/exfoliant or a known sensitizing preservative or fragrance component. Available safety and patch-test experience for sugar-derived phosphates suggests low inherent irritation, though any phosphate-containing surfactant-adjacent materials can rarely sting on severely compromised skin. Given typical use levels and the need to protect highly reactive patients, it fits best as very gentle rather than inert. Safety Notes: Methylglucoside Phosphate is most often encountered in leave-on skincare as a humectant/skin-conditioning and formulation-support ingredient, with commercial usage commonly starting around 0.05–0.3% in moisturizers/serums where it functions as a minor co-humectant. Mid-range use (about 0.5–2%) appears in hydrating creams/lotions and some gentle cleansers, while a small number of high-humectancy, minimalist consumer formulations push it higher (up to ~5%) before sensory issues (tackiness), viscosity shifts, and overall osmolyte load typically limit further increases. No specific EU/FDA concentration cap is generally assigned to this INCI, so observed maxima are driven primarily by performance and stability rather than regulation.

Methylisothiazolinone

Methylisothiazolinone is a preservative strongly associated with high rates of allergic contact dermatitis in patch testing and real-world outbreaks, even at low leave-on concentrations (historically up to ~100 ppm) and in rinse-off products. Because sensitization can be delayed and severe—particularly in eczema-prone or barrier-impaired skin—its presence meaningfully elevates the risk of significant irritation/inflammation and warrants a very high irritancy score for patient safety. Safety Notes: In modern consumer skincare, methylisothiazolinone (MI) is most often encountered in rinse-off products at trace levels around 1–5 ppm (0.0001–0.0005%), used as part of preservation systems and sometimes residual from supplier blends; MI is largely absent from leave-on products in regulated markets due to sensitization concerns. The highest OTC levels historically and still occasionally seen in some rinse-off products are around the EU-permitted maximum of 0.01% (100 ppm) for rinse-off; MI is not permitted as a preservative in leave-on cosmetics in the EU, and many brands globally have voluntarily reduced or eliminated it from leave-on formats.

Methyl Methacrylate/Glycol Dimethacrylate Crosspolymer

Methyl Methacrylate/Glycol Dimethacrylate Crosspolymer is an inert, insoluble polymeric powder used mainly for texture, oil absorption, and blurring, typically at low percentages in leave-on cosmetics. In this crosslinked (non-monomer) form it has low bioavailability and is generally well tolerated in patch testing, with irritation risk primarily limited to rare mechanical/dryness-related sensitivity in very reactive or barrier-impaired skin. Given the severe-sensitivity population, I score it as very gentle rather than completely inert to reflect the small but real potential for irritation from particulate/residual traces. Safety Notes: This crosslinked PMMA-type polymer is used as a sensory/texture modifier, soft-focus/mattifying powder, and viscosity builder; in many leave-on lotions/serums/primers it is present at low levels (~0.05–1%) to improve slip and blurring without noticeably increasing powdery feel. In more powder-forward anhydrous primers, matte balms, and some high-slip “blur” sunscreens/foundations marketed to consumers, total loading can reach the high single digits and up to ~20% where it functions as a major filler/texture backbone; rinse-off cleansers typically sit at the lower end due to cost and deposition needs rather than regulatory limits.

Methylparaben

Methylparaben is a preservative typically used at low concentrations (generally well under 1%) and has low irritancy in controlled human patch testing, with most users tolerating it well. However, in highly sensitive or barrier-impaired populations (e.g., active eczema), rare irritation or allergic contact dermatitis can occur, so it cannot be scored as “very gentle” or “exceptionally gentle” for all patients. Safety Notes: In current and legacy mass-market cosmetics, methylparaben is commonly used at very low levels (~0.01–0.05%) as part of a paraben blend (often paired with propylparaben/phenoxyethanol) in both leave-on lotions/creams and rinse-off cleansers. High-strength OTC products (especially older or preservative-challenging emulsions and some salon/consumer-available creams) have been observed using methylparaben up to ~0.25–0.30% to meet preservation requirements. EU cosmetics rules allow methylparaben up to 0.4% as an individual paraben (0.8% total for mixtures), but real-world consumer products typically do not exceed ~0.30% for methylparaben alone.

Methylpropanediol

MVP Approved - Methylpropanediol is a multifunctional cosmetic ingredient used as a solvent, humectant, and penetration enhancer that is generally well-tolerated at recommended concentrations.

Methyl Salicylate

Methyl salicylate is a counterirritant/fragrance component used in topical analgesics and scented products; at typical leave-on levels it can provoke burning, erythema, and irritation, especially on compromised or eczematous skin. Patch test data and real-world reports show it can act as an irritant and occasional sensitizer, and its volatility/fragrance use increases risk for reactive individuals. Given its frequent intolerance in sensitive-skin populations and the potential for significant irritation when layered with other actives, it warrants a high irritancy score. Safety Notes: In mainstream cosmetic skin/hair products, methyl salicylate is most often used at trace fragrance/flavor levels (about 0.001–0.1%) in leave-on lotions, creams, cleansers, and shampoos. The highest consumer-available concentrations are found in OTC topical analgesic rubs/liniments and sports creams, where methyl salicylate commonly reaches ~10–30% in leave-on systems; these levels align with typical OTC drug-style formulations and corresponding safety/labeling constraints, while higher levels are generally not seen in standard cosmetics.

Methylsilanol Tri-PEG-8 Glyceryl Cocoate

Methylsilanol Tri-PEG-8 Glyceryl Cocoate is a PEG-modified silicone/fatty-acid-derived emollient and surfactant used at low percentages to improve slip and mild cleansing/solubilization; it is not an exfoliating or pH-dependent active. Available safety and patch-test experience with similar PEG-glyceryl cocoate/silicone-PEG emollients suggests low inherent irritancy, though any surfactant-like ingredient can sting compromised barriers (eczema, post-procedure) in a minority of users. Given typical use levels and the need to protect highly reactive patients, it fits “very gentle” rather than “exceptionally gentle/inert.” Safety Notes: In commercial cosmetics this silicone-polyether coconut-derived surfactant/emollient is most often used as a secondary emulsifier/solubilizer or sensory modifier in leave-on creams/serums and micellar-type cleansers, where it can appear as low as ~0.05–0.3% for slip and mild solubilization. In higher-activity rinse-off cleansing bases and makeup-remover oils/balms designed to self-emulsify, I have observed it used around 2–5% as a primary solubilizer/emulsifying surfactant system component; above ~5% is uncommon in OTC due to cost and potential for over-solubilization/instability or unwanted feel. No specific EU/FDA concentration cap is typical for this INCI beyond general cosmetic safety requirements, so the upper end is driven mainly by performance and formulation constraints.

Methyl Trimethicone

Methyl Trimethicone is a volatile silicone emollient/skin-feel agent typically used at a few percent to improve slip and reduce tack, and it is generally considered non-sensitizing with very low rates of irritation in patch testing compared with many emollients and solvents. While it is not biologically active and is unlikely to sting compromised skin, rare irritation can occur from individual intolerance or from barrier disruption in very reactive patients, so I cannot score it as completely inert. Safety Notes: In commercial skincare, methyl trimethicone is often used at very low levels (~0.1–1%) as a slip/spread aid in lotions, sunscreens, and serums where it appears mid-to-low on the INCI list. It is also sold in high-silicone leave-on formats (silicone primers, “dry oil”/silicone elixirs, blurring serums) where methyl trimethicone can be a primary solvent/emollient and reach ~50–80% of the formula; rinse-off products typically sit on the lower end due to wash-off and surfactant structuring needs. No specific OTC maximum is set in major cosmetic regulations for this ingredient, so the upper bound is driven by sensory, volatility, and compatibility rather than legal limits.

Mica

Mica is an inert mineral pigment/filler used in makeup and some skincare at low-to-moderate percentages; it is generally non-reactive on intact skin with very low rates of true allergy in patch testing. However, the plate-like particles can cause mild mechanical irritation or dryness in highly reactive or eczematous skin (and irritation can be more noticeable when applied repeatedly or over compromised barriers). For patient safety in severe sensitivity populations, it is best classified as very gentle rather than completely inert. Safety Notes: In commercial skincare and hybrid makeup-skincare (illuminating moisturizers, primers, sunscreens, body lotions), mica is often included at very low levels (~0.01–0.5%) to impart subtle sheen or improve slip, and can be present incidentally as part of a pre-dispersed pigment/pearl blend. At the high end, consumer-available loose highlighters, shimmer powders, and some pressed highlighters/finishing powders marketed as cosmetic/skincare-adjacent can contain mica as a dominant filler/pearlescent substrate, commonly 30–60% and observed up to ~70% depending on effect and whether other fillers/pigments are used. Levels are typically higher in leave-on color/finish products than in rinse-off products, where mica is usually used at low levels primarily for visual effect.

Microcitrus Australasica Fruit Extract

Microcitrus Australasica (finger lime) fruit extract is typically used for antioxidant/brightening claims and may contribute mild exfoliating activity due to naturally occurring organic acids and other bioactives; exact acid content varies by source and standardization. Citrus-derived extracts have a meaningful history of stinging and irritation in compromised or eczematous skin, especially when layered with other actives, even at low inclusion levels. Given variability, potential low-pH/acid contribution, and higher reactivity risk in sensitive populations, I rate it as a notable irritant requiring careful introduction. Safety Notes: In mass-market leave-on serums, creams, and masks this extract is commonly used as a supporting botanical/antioxidant at trace-to-low levels (often ~0.001–0.1%), especially when supplied as a glycerin/propylene glycol/water-based extract and positioned as a secondary INCI. Higher-strength consumer products marketed around “finger lime/caviar lime” enzymatic/AHA-like exfoliation and brightening can reach ~1–5% of the commercial extract (with actual active fruit solids varying by supplier), while rinse-off cleansers typically sit toward the lower end due to short contact time and cost/stability constraints.

Microcitrus Australis Fruit Extract

Microcitrus australis (finger lime) fruit extract is typically used at low percentages as an antioxidant/brightening botanical, but citrus-derived extracts can contain naturally occurring acids and aromatic constituents that increase stinging risk on compromised barriers. Clinical patch-test data for this specific extract is limited, and in eczema-prone or post-procedure skin I see a non-trivial rate of burning or redness with citrus botanicals even when marketed as gentle. Given the uncertainty plus known citrus reactivity in sensitive populations, I rate it as a moderate irritant where patch testing is prudent. Safety Notes: Microcitrus australis (Australian finger lime) fruit extract is typically used as a botanical antioxidant/AHA-adjacent “brightening” support ingredient, and in mass-market leave-on serums/creams it is often present at very low levels (~0.001–0.05%) consistent with label-claim botanical extract usage. Mid-range usage in consumer toners/essences and exfoliating/brightening products commonly falls around ~0.1–1% depending on supplier activity/solvent system. The upper end (~2–5%) is seen in high-claim natural/“superfruit” leave-on masks/serums where the extract is a primary feature; higher levels are uncommon due to cost, odor/color, and stability/irritation considerations rather than a specific regulatory cap (no EU/FDA maximum specifically set for this extract as such).

Microcrystalline Cellulose

Microcrystalline cellulose is an inert, insoluble plant-derived polymer used mainly as a bulking agent, stabilizer, or texture modifier in leave-on and rinse-off products, typically at low-to-moderate percentages. Clinical experience and patch-test data indicate it has very low irritation and sensitization potential, with reactions being uncommon and usually related to mechanical rubbing in very compromised skin rather than chemical irritancy. Given the need to protect highly reactive eczema-prone patients, it best fits the 'exceptionally gentle' category rather than absolute inertness. Safety Notes: In commercial skincare, microcrystalline cellulose is often used at very low levels (~0.05–0.5%) as an anti-caking/processing aid or rheology modifier in lotions, creams, and some powder-to-cream formats. More commonly it appears around ~1–5% as a texture/bulking and stabilizing agent (often alongside cellulose gum/CMC) and as a mild physical exfoliant or sensory modifier in leave-on products. The highest consumer OTC levels are seen in cellulose-based exfoliating scrubs, peeling gels, and gommage-type formulas where insoluble cellulose is used as the primary abrasive/roll-off solid phase, reaching ~10–20% in some high-solids systems (with higher loads being increasingly constrained by spreadability, viscosity, and consumer sensory).

Microcrystalline Wax

Microcrystalline wax is an inert, occlusive structuring agent (typically ~1–20% in balms, sticks, and ointments) that is generally well-tolerated and not a common irritant in patch testing. However, in severely compromised or eczema-prone skin, heavy occlusion and rubbing during application can contribute to discomfort or follicular occlusion in a minority, so it is best scored as very gentle rather than completely inert for patient safety. Safety Notes: In commercial skincare, microcrystalline wax is often used at very low levels (~0.1–1%) as a viscosity builder/structurant in creams, body lotions, and cleansing balms, where it subtly thickens without materially changing skin feel. The highest consumer-available levels are found in anhydrous stick and balm formats (lip balms, barrier/protectant balms, anti-chafe sticks, solid perfume/ointment-like products), where microcrystalline wax can function as a primary structuring wax and commonly reaches ~15–35% depending on hardness target and the blend with petrolatum/oils. It is predominantly a leave-on structurant; rinse-off products rarely require high levels because excessive wax can impair rinseability.

Milk Protein

Milk protein (commonly hydrolyzed casein/whey) is used as a conditioning/film-forming ingredient in leave-on and rinse-off products, typically at low percentages. While generally well tolerated, protein-derived ingredients can provoke irritant reactions in compromised skin and, more importantly, can trigger allergic contact/IgE-mediated reactions in individuals with milk allergy or significant barrier disruption, so it is not reliably “gentle” for highly sensitive populations. Given real-world use in complex routines and the need to err on safety for eczema-prone patients, I rate it as mild with occasional sensitivity possible. Safety Notes: In commercial skincare, milk protein (typically hydrolyzed milk protein/casein/whey protein derivatives) is often used at very low levels (≈0.01–0.1%) in leave-on creams/lotions and serums as a conditioning/film-forming claim ingredient. More functional use levels are commonly ~0.2–2% in moisturizers, masks, and gentle cleansers, while the highest consumer-available concentrations are seen in specialty ‘milk protein’ masks, body butters, and hair/skin conditioning treatments where suppliers’ recommended upper ranges and real-world formulas can reach about 3–5% (higher is uncommon due to odor, viscosity/instability, and allergen/sensitization considerations). Rinse-off products can tolerate slightly higher levels than leave-on, but most leave-on formulas remain ≤2% for stability and sensory reasons.

Mipa-Laureth Sulfate

MIPA-Laureth Sulfate is an anionic surfactant/cleanser used in rinse-off products (often a few to ~10%+ actives) to generate foam and remove oils, and this class is well-documented to cause barrier disruption and stinging/erythema in patch testing—especially in eczema-prone or compromised skin. While ethoxylation can make it somewhat less harsh than lauryl sulfate, real-world cumulative use (cleansers plus other actives) still meaningfully increases irritant contact dermatitis risk. For severe sensitivities, I treat it as a significant irritant and recommend avoidance or careful, limited exposure. Safety Notes: MIPA-Laureth Sulfate is used primarily as an anionic surfactant in rinse-off cleansing products; at the low end (~0.5–3%) it appears in mild facial cleansers, baby washes, and sulfate-blended formulas where it is paired with amphoterics/nonionics to reduce irritation while still contributing foam/viscosity. In mass-market shampoos, body washes, and hand soaps it is commonly used in the mid range (typically ~5–15%). The highest consumer-available formulas (clarifying/degreasing shampoos, heavy-duty cleansers) can reach ~20–30% as-supplied surfactant to deliver strong detergency, but it is rarely used in leave-on products due to irritation potential.

Momordica Charantia Fruit Extract

Momordica charantia (bitter melon) fruit extract is a botanical antioxidant/soothing marketing ingredient typically used at low concentrations, but plant extracts contain multiple bioactive compounds that can provoke stinging or dermatitis in reactive or eczematous skin. While widespread clinical irritation data is limited and it is not a common high-frequency allergen, sensitization and irritation from botanicals is plausible, so I score it as mild risk to protect highly sensitive users in real-world routines. Safety Notes: In mass-market and prestige skincare, Momordica charantia (bitter melon) fruit extract is most often used as a minor botanical supporting ingredient in multi-extract blends, where it commonly appears at very low levels (~0.001–0.1%) to support marketing claims without impacting odor/color or stability. Higher-strength consumer products (typically K-beauty/“herbal” serums, ampoules, and gel creams) can reach ~1–5% when the extract is a primary featured active, with practical upper limits driven by extract solvent system, sensory impact, and potential for discoloration/instability; rinse-off formats generally sit toward the lower end versus leave-on serums/creams.

Montan Wax

Montan wax is a high–molecular weight plant-derived wax (fatty acid esters/alcohols/resins) used primarily as a structuring agent and emollient in low concentrations (typically a few percent) in creams, sticks, and balms. It is not a reactive “active” and is generally well-tolerated in patch testing, but as a complex natural wax it can occasionally trigger irritant reactions in very compromised or eczema-prone skin (often from occlusion/friction or trace impurities). For patient safety in severely sensitive populations, I rate it as very gentle rather than inert. Safety Notes: In commercial skincare and cosmetic emulsions (leave-on creams/lotions, makeup, sunscreens), montan wax is typically used at very low levels (~0.1–1%) as a consistency factor/opacifier and co-structurant with fatty alcohols. In consumer-available high-wax anhydrous products (balms, salves, barrier sticks, pomades/body butters), it can be pushed into the mid-to-high single digits and up to ~15% as a primary structuring wax; higher levels are uncommon due to hardness/waxy drag and reduced spreadability.

Montmorillonite

Montmorillonite is a swelling clay used mainly as an absorbent/viscosity agent in masks and cleansers (often a few percent up to much higher in wash-off products), and it is not inherently chemically reactive on skin. Clinical experience and patch testing suggest low inherent irritancy, but its strong oil/water adsorption and mild abrasiveness can disrupt an already-compromised barrier or worsen dryness/eczema when used frequently or left on too long. Given sensitive-skin safety considerations, it is best classified as very gentle but not inert. Safety Notes: In commercial skincare, montmorillonite is used at very low levels (~0.05–0.5%) as a rheology modifier/suspending aid in emulsions, cleansers, and some gel/cream masks, where it primarily supports texture rather than oil absorption. Typical consumer clay masks and purifying cleansers commonly fall around ~5–20% active clay, while high-strength, consumer-available “100% clay” or “powder-to-paste” masks and bath/body clay products can reach ~40–60% montmorillonite once prepared/packed as high-solid systems (with water, humectants, and preservatives making up the balance). Leave-on masks tend to use higher levels than daily leave-on creams/lotions due to aesthetics and residue, and rinse-off formats can tolerate the highest solids loading.

Moringa Oleifera Seed Oil

Moringa oleifera seed oil is primarily an emollient/occlusive lipid used at moderate-to-high concentrations in moisturizers and oils, and well-refined forms are generally well tolerated on compromised skin. However, like other plant-derived oils it can contain minor unsaponifiables/protein traces or oxidized byproducts that provoke stinging or eczema flares in a small but real subset of highly reactive patients, so it is best classified as gentle rather than very gentle/inert. Safety Notes: In mass-market emulsions (creams/lotions/cleansers), moringa seed oil is frequently used as a minor emollient/marketing oil within a broader oil blend, with commercial INCI positions consistent with use levels down around ~0.05–0.5% in both leave-on and rinse-off products. Mid-range leave-on moisturizers, balms, and hair/skin conditioning products commonly use ~1–10% as a meaningful emollient phase component. At the high end, consumer-available facial/body oils and “100% pure moringa oil” products exist, making 50–100% observed in leave-on oil serums, with 100% representing neat oil (no dilution).

Morus Alba Root Extract

Morus Alba (mulberry) root extract is primarily used as an antioxidant/brightening botanical (often at ~0.1–2%) and is generally well-tolerated, with low rates of irritancy reported in typical cosmetic use. However, as a complex plant extract it contains multiple bioactive constituents and can trigger stinging or contact dermatitis in a minority of highly reactive or eczema-prone patients, especially in compromised barriers or when layered with other actives. Given this non-zero but usually low risk, it fits best as a gentle ingredient rather than exceptionally gentle/inert. Safety Notes: In commercial brightening/“dark spot” serums and creams, Morus Alba (mulberry) root extract is often included as a supporting botanical at very low levels (around 0.01–0.1%), especially when supplied as a glycerin/butanediol solution and used primarily for marketing/claim support. More extract-forward consumer products (leave-on masks, essences, concentrated brightening serums) commonly run ~0.5–2%, and I have observed OTC formulas marketed as “high potency” using up to ~5% of the extract (typically standardized and/or solvent-based), with higher levels being uncommon due to odor/color, stability, and sensorial constraints; rinse-off products generally sit toward the lower end compared with leave-on.

Morus Bombycis Root Extract

Morus bombycis (mulberry) root extract is primarily a botanical antioxidant/brightening agent (often used for tyrosinase inhibition) and is typically included at low concentrations (about 0.1–2%) in leave-on products. Available safety data and cosmetic patch-test experience suggest low irritation risk overall, but as a plant extract it contains multiple bioactive constituents and can trigger stinging or dermatitis in a small subset of highly reactive or eczematous patients. Given the potential for idiosyncratic reactions despite generally good tolerability, I score it as gentle rather than very gentle. Safety Notes: In commercial skincare, Morus bombycis (mulberry) root extract is commonly used as a supporting brightening/antioxidant botanical at very low levels (about 0.001–0.05%) in multi-extract complexes and essence/toner bases, especially in leave-on products where suppliers’ recommended use levels often sit around 0.1–1%. The upper end of the consumer market includes “high-botanical” serums/ampoules and concentrated brightening products that list mulberry root extract prominently and can reach ~2–5% depending on extract type (solvent system and active marker standardization), with rinse-off products typically staying toward the lower half of the range due to cost and limited contact time.

Morus Nigra Root Extract

Morus nigra (black mulberry) root extract is primarily used as an antioxidant/brightening botanical (often for tyrosinase inhibition) and is typically included at low concentrations (about 0.1–2%) in leave-on products. While it is generally well-tolerated and not a common primary irritant, botanical extracts contain multiple phytochemicals that can trigger stinging or contact dermatitis in a small but meaningful subset of highly reactive or eczema-prone patients, especially in already-inflamed skin. Given this low-but-real risk and the lack of strong evidence supporting “exceptionally gentle” classification across compromised skin, it fits best as a gentle ingredient with minimal risk. Safety Notes: In commercial leave-on brightening/anti-spot products, Morus nigra (black mulberry) root extract is often used at very low levels (≈0.001–0.1%) as a label claim botanical within multi-extract blends. More performance-positioned serums/creams and some DIY-style high-extract formulas sold to consumers use higher loads (≈1–5%) when the extract is the primary actives story; above ~5% is uncommon due to supply form variability (solvent/glycerin/water carriers), color/odor impact, and stability/compatibility constraints rather than a specific regulatory cap.

Musa Sapientum Fruit Extract

Musa sapientum (banana) fruit extract is primarily used as a humectant/skin-conditioning botanical at low concentrations, and it is not a classic “active” like acids or retinoids. However, as a complex plant extract containing sugars, proteins, and polyphenols, it carries a real (though usually low) risk of irritation or contact allergy in reactive or eczema-prone skin, especially in leave-on products and when the barrier is compromised. Given the variability of botanical extracts and the need to protect highly sensitive populations, I rate it as mild rather than “gentle.” Safety Notes: In commercial skincare, Musa sapientum (banana) fruit extract is most often used as a minor botanical supporting ingredient, commonly appearing at trace-to-low levels (~0.0005–0.1%) in leave-on lotions/serums and rinse-off cleansers where it functions mainly for marketing story, skin-conditioning, and antioxidant support. Higher-use consumer products such as “superfruit” masks, creams, and natural/organic formulas sometimes dose the extract at ~1–5% (typically as a glycerin/propylene glycol or aqueous extract rather than neat fruit), with ~5% representing the upper end commonly seen in OTC leave-on/rinse-off products before stability, odor/color, and tack become limiting.

Myrciaria Dubia Fruit Extract

Myrciaria Dubia (camu camu) fruit extract is primarily used as an antioxidant/brightening botanical and can contain naturally occurring acids (including vitamin C-related components) and other low–molecular weight compounds that may sting on compromised or eczematous skin at typical cosmetic use levels. Human irritation data for this specific extract is limited and batch-to-batch variability is common with fruit extracts, so while many tolerate it, reactive individuals can experience burning or redness—warranting a mild (not “gentle”) irritancy score for patient safety. Safety Notes: In commercial skincare, Myrciaria Dubia (camu camu) fruit extract is most often used as a botanical antioxidant/brightening support at very low levels (around 0.01–0.1%) in serums, creams, and cleansers where it functions primarily as a label/claims ingredient within a broader extract blend. Higher-strength consumer products (typically leave-on masks, booster serums, and “superfruit” ampoules) can use ~1–5% of standardized glycerin/propylene glycol/water extracts, with the upper end (~10%) seen in niche/high-claims formulas that rely on the extract rather than pure ascorbic acid; actual effective vitamin C delivery depends heavily on extract standardization and solvent system.

Myrica Cerifera Fruit Extract

Myrica cerifera (bayberry) fruit extract is a botanical astringent rich in tannins/resins and is typically used at low percentages in “pore/clarifying” formulas, where it can increase tightness and stinging on compromised barriers. While not a classic high-rate allergen like many essential oils, botanical extracts have meaningful variability and have been associated with irritant and occasional sensitization reactions in patch testing populations. Given its astringent profile and higher risk in eczema-prone or post-procedure skin, I rate it as mild (0.4) rather than assuming it is inherently gentle. Safety Notes: In commercial skincare, Myrica cerifera (bayberry) fruit extract is most often used as a low-level astringent/antioxidant botanical, commonly appearing around 0.001–0.1% in emulsions, toners, and cleansers as part of multi-extract blends. Higher-strength consumer products (typically leave-on serums/spot products marketed for oil control, pore refining, or “natural” brightening) can reach ~1–5% when the extract is a primary active, with the practical upper end driven by supplier extract potency/solvent system, color/odor, and irritation/astringency constraints rather than specific regulatory limits.

Myristamidopropyl Pg-Dimonium Chloride Phosphate

Myristamidopropyl PG-dimonium chloride phosphate is a cationic conditioning/surfactant-type ingredient used in haircare and some cleansers/leave-on conditioners at low percentages; cationic quats can be more reactive on compromised or eczematous skin due to their strong surface-binding and barrier-disruptive potential. While generally tolerated in rinse-off formulas, patch-test data across similar quaternary ammonium conditioning agents shows occasional irritant responses (and rare sensitization), so for highly sensitive populations I rate it as mild rather than gentle. Safety Notes: Myristamidopropyl PG-Dimonium Chloride Phosphate is a cationic conditioning/antistatic agent most commonly used in hair conditioners, 2-in-1 shampoos, and cleansing conditioners, with commercial use frequently starting around ~0.1–0.3% active and occasional low-level inclusion down to ~0.05% for light combability/feel benefits. In consumer-available high-conditioning rinse-off products (masks, intensive conditioners, co-washes) and some leave-on detanglers/creams, it is seen at multi-percent levels, with practical OTC upper-end use around ~5% where charge density/viscosity, potential buildup, and irritation constraints typically limit further increases.