Ingredient dossier Nº 014 / The verified record
Kojic Acid
KOJIC ACID
Effective concentration, the pH it needs, how the derivatives compare, stability in the bottle, and the open questions — every scientific claim on this page links to its source.
- skin-conditioning agent
- tyrosinase inhibitor
- antioxidant
- skin-brightening agent
Editorial verdict / Social intelligence
The most potent gentle brightener for stubborn spots — but also the most irritating and least stable of the OTC options; patch test mandatory and toss it when it browns. 1
- Beauty benefit
- Potent OTC tyrosinase inhibitor with clinical trial evidence for melasma and post-acne hyperpigmentation — stronger mechanism than arbutin or niacinamide on stubborn spots. Key trade-off: higher sensitization and irritation risk than gentler alternatives, significant oxidative instability (products turn brown/yellow when degraded), and the EU/UK regulatory ceiling of 1% in leave-on products. Works best in stable, well-formulated products with opaque/airtight packaging; requires patch testing; not appropriate for sensitive or reactive skin.
- Does it work
- Qualified yes — with real caveats. Clinical evidence is solid: 1% monotherapy achieved 58% MASI reduction at 12 weeks in a randomised trial, and kojic acid adds meaningful benefit in combination brightening formulas alongside hydroquinone and glycolic acid. Dermatologists consistently recommend it for stubborn dark spots, post-acne marks, and melasma. The caveats are real: higher sensitisation risk than arbutin or niacinamide (contact dermatitis within 1–12 months of use is documented), significant oxidative instability (products degrade and lose potency), and a narrow effective-plus-safe concentration window of 1–2%. Sensitive skin types are better served by gentler alternatives. See the science below →
Consensus strength
StrongStrong consensus across dermatologists, editorial sources, and regulatory bodies that kojic acid is an effective OTC tyrosinase inhibitor at 1–2% with clinical evidence for melasma and hyperpigmentation. Equally strong consensus on its two defining limitations: higher sensitisation/irritation risk than gentler brighteners (documented allergic contact dermatitis within 1–12 months in a subset of users), and oxidative instability in aqueous formulations (characteristic yellow-to-brown discolouration signals potency loss). The EU and UK have codified the 1% maximum in Regulation (EU) 2024/996 and SI 2024/1334. No dissenting view on mechanism or safety profile at 1% — only the honest acknowledgment that sensitisation risk is higher than niacinamide or alpha-arbutin, making it unsuitable for sensitive or reactive skin types.
01 / What it does
What it does
Kojic acid is a naturally occurring fungal metabolite produced during fermentation by Aspergillus and Penicillium species (notably in koji — fermented rice/soy). Its primary mechanism in skin is inhibition of tyrosinase, the rate-limiting enzyme in melanin synthesis: kojic acid chelates the copper ions at tyrosinase's active site, preventing the enzyme from oxidising L-tyrosine to L-DOPA and onward to melanin. It is one of the more potent OTC tyrosinase inhibitors in common use and has clinical evidence in melasma and post-inflammatory hyperpigmentation at concentrations of 1–2%. Key limitations are its chemical instability (it oxidises and turns yellow-brown on exposure to light, air, and iron, losing potency) and a higher rate of contact sensitisation compared with gentler brighteners. The EU SCCS has set a maximum permitted concentration of 1% in leave-on facial cosmetics.
- Source Kojic acid acts as a slow-binding competitive inhibitor of the catecholase activity of tyrosinase; kinetic analysis shows rapid formation of an initial enzyme-inhibitor complex followed by slow reversible isomerisation, consistent with copper chelation at the enzyme's active site. 1
- Study 1% kojic acid monotherapy achieved a 58% reduction in MASI (Melasma Area and Severity Index) at 12 weeks in a randomised, single-blind comparative trial (n = 60). 2
- Source A kojic acid-containing gel (2% KA, 2% HQ, 10% glycolic acid) produced 60% complete clearance of melasma in a split-face RCT of 40 Chinese women, compared with 47.5% for the non-KA control arm, establishing clinically meaningful additive efficacy. 3
- Study A serum combining tranexamic acid, kojic acid, and niacinamide produced significant improvement in facial dyschromia over 12 weeks in a clinical evaluation, supporting the use of kojic acid in multi-brightener formulations. 4
02 / Effective concentration
What percentage actually works
Effective range
1-2%
1–2% in leave-on formulations; the EU SCCS sets a regulatory maximum of 1% in face creams and body lotions. Clinical efficacy for hyperpigmentation is demonstrated at 1% monotherapy (Deo 2013) and at 2% in combination products (Lim 1999).
The effective concentration for hyperpigmentation treatment is consistently 1–2% in peer-reviewed trials. The EU SCCS/1637/21 opinion (2022) concluded that kojic acid is safe as a skin-lightening ingredient at concentrations up to 1% in face creams (leave-on), face wash/cleansing products, and body lotions. CIR (2010) likewise concluded safety below concentrations at which sensitisation occurs. Concentrations above 2% are not established to offer greater efficacy and increase sensitisation risk.
- Study 1% kojic acid monotherapy achieved a 58% reduction in MASI at 12 weeks in a randomised, single-blind trial (n = 60); the 1% concentration was the treatment arm throughout the study. 2
- Source The EU SCCS concluded that kojic acid is safe as a skin-lightening ingredient in face creams and body lotions at concentrations up to 1% (leave-on); the opinion also covers face wash/cleansing products. 18
- Source A split-face RCT using 2% kojic acid in a combination gel demonstrated clinically meaningful hyperpigmentation clearance, supporting the upper end of the 1–2% effective range. 3
One honest caveat Direct head-to-head RCTs comparing kojic acid monotherapy to hydroquinone monotherapy at matched concentrations in the same patient population are limited; most comparison data comes from combination formulations.
03 / pH requirement
The pH it needs
Target pH
Mildly acidic — pH 3.5–6.5 (optimal stability pH ~3.5–5; physiological-range formulations possible)
Unlike L-ascorbic acid, kojic acid does not require an aggressive low pH (below 3.5) for skin penetration; it is a small neutral molecule at typical cosmetic pH ranges and can be formulated at mildly acidic to near-neutral pH. However, stability is pH-dependent: aqueous solutions are more stable at acidic pH. Alkaline conditions and iron ions (Fe3+) markedly accelerate oxidative degradation. Formulation at pH 3.5–6.5 is conventional; the practical lower bound is irritation tolerance rather than a penetration requirement.
- Study Kojic acid undergoes first-order oxidative degradation in aqueous solution; degradation is accelerated by alkaline pH, iron ions (Fe3+), and light — the iron-catalysed oxidation pathway is particularly relevant in formulation stability. 6
- Study Photostability of kojic acid in aqueous solution is lower than in microemulsion formulations; encapsulation or emulsification significantly improves resistance to light-induced degradation. 7
04 / Derivative ladder
How the derivatives compare
Every derivative trades a measure of proven activity for stability or gentleness. Skin conversion is the question that matters — a more stable molecule only helps if your skin can turn it back into the active form.
-
Kojic Dipalmitate
KOJIC DIPALMITATE
Skin conversion partially — requires esterase hydrolysis
Kojic dipalmitate (KDP) is the dipalmitoyl ester of kojic acid. It is lipophilic, substantially more stable to oxidation and heat than free kojic acid, and does not discolour on routine cosmetic shelf life. It requires enzymatic (esterase) hydrolysis in skin to release free kojic acid; the extent of this conversion in vivo is not well quantified. KDP is used widely in marketed brightening products as a stability-forward alternative. However, direct head-to-head clinical trials comparing KDP to free kojic acid at matched concentrations are very limited. The SCCS/1637/21 opinion covers kojic acid only — KDP is not covered by the same EU regulatory limit, but neither has the same evidence base.
Stability edge Lipid-soluble; does not undergo aqueous oxidative degradation and does not produce the characteristic brown discolouration of free kojic acid. Superior photostability and thermal stability in solid and lipid-based formulations.
- Study Kojic dipalmitate nanoemulsion demonstrated tyrosinase inhibitory activity in vitro and epidermal delivery without significant dermal penetration, with >95% encapsulation efficiency and droplet size <130 nm. 9
- Study Under liquid-phase oxidative stress (H₂O₂), kojic dipalmitate degraded more rapidly than free kojic acid; however, in solid/lipid formulations, KDP showed superior photostability and thermal stability — the comparison is formulation-context dependent. 6
05 / Stability & storage
Stability in the bottle
Kojic acid is chemically unstable in aqueous formulations. It oxidises on exposure to light, air (dissolved oxygen), and trace iron ions (Fe3+), producing first a yellow, then brown-orange discolouration — a visible indicator of degraded activity. This colour change is the same iron-mediated pathway that limits shelf life of water-based kojic acid formulas. Unlike L-ascorbic acid (where the degradation chromophore is well-characterised dehydroascorbic acid), kojic acid's oxidation produces iron–kojic acid chelate complexes. Thermal stress and high pH further accelerate degradation. Practical formulation strategies include: avoiding iron-containing ingredients or processing equipment, using antioxidant co-ingredients, opaque/airless packaging, and emulgel or microemulsion formats that improve photostability. The lipophilic ester kojic dipalmitate was developed partly to address this instability — it does not discolour as readily — but has less clinical evidence for efficacy (see derivatives).
- Study Under oxidative stress (H₂O₂), kojic acid in aqueous solution undergoes first-order degradation with characteristic yellow-to-brown discolouration; iron (Fe3+) is identified as a primary catalytic oxidant responsible for the colour change observed in topical products. 6
- Study Kojic acid in aqueous solution degrades rapidly on photostress; formulation as a microemulsion significantly improved photostability, with linalool demonstrating a protective co-ingredient effect against light-induced degradation. 7
- Source Emulgel formulation significantly improved the stability of kojic acid compared with conventional cream bases, with reduced colour development and retained potency over the study period. 8
In practice Buy it in an opaque, airless, or amber container, store it cool and out of the light, and treat a colour shift toward orange or brown as the signal to replace it — the molecule is telling you it has already oxidised.
06 / How to use it
How to actually use Kojic Acid
- When
- PM (or AM) — After cleansing, before moisturizer.
- Pairs well with
- niacinamide, vitamin C, alpha-arbutin.
- Apply apart from
- layering with several strong actives at once(use one in the morning, the other at night — not “never together”)
- What to look for
- 1–2%.
- Heads-up
- Can sensitize — patch-test, introduce slowly, and use SPF. It oxidizes (color shift) over time.
Practical guidance for routine placement — not a substitute for a dermatologist’s advice for your skin.
07 / The database
Kojic Acid: measured product rankings coming soon
Ranked by $ per gram of active — what the working ingredient actually costs you, not the sticker price. Rows we have reviewed in full link through; the rest are data points from the same crawl.
Buy Kojie San on Amazon $9.93 Top-ranked pick · affiliate link
No measured products yet — this active's price-per-gram rankings will appear here as products are added.
In the meantime, see how to use Kojic Acid and what to look for on a label , or compare it with every other brightening active.
Contains it, but doesn't disclose a percentage: Good MoleculesBrightening & Dark Spots Bar ; Kojie SanKojie San Skin Lightening Soap ; BYOMABlemish Acne Treatment Spot Paste ; Peach SlicesSuper Fade Discoloration Serum ; Urban Skin RxEven Tone Cleansing Bar 3-in-1 Treatment - 2.0 oz ; medicubeKojic Acid Turmeric Toning Cleanser — and 14 more.
08 / Safety
Is it safe?
Reviewed by the Cosmetic Ingredient Review — safe as used
Safe as used at concentrations where sensitisation and depigmentation effects would not occur — CIR Final Report 2010 (PMID:21164073). A CIR Amended Safety Assessment was issued for public comment in March 2025 (status: insufficient data determination; final amended report not published as of June 2026). The EU SCCS SCCS/1637/21 (2022) concluded kojic acid is safe at up to 1% in leave-on facial and body products.
Contact sensitisation is the primary safety concern: patch test studies found positive reactions in a subset of patients using kojic acid products, and facial dermatitis developing after weeks to months of use has been documented. Sensitisation rate is considered higher than for gentler brighteners (e.g., niacinamide, alpha-arbutin). A paradoxical pigmented contact dermatitis (darkening from a lightening agent) has been reported. Carcinogenicity: oral and dietary administration at high doses induced thyroid follicular adenomas in mice and hepatocellular tumours in some rat models; these effects are non-genotoxic and dose-threshold dependent. Topical application at 1% with low systemic exposure was reviewed by SCCS and deemed acceptable. No skin carcinogenicity or photo-genotoxicity was found in mouse skin topical application studies.
- CIR CIR Expert Panel (2010) concluded kojic acid is safe in cosmetics at concentrations at which sensitisation and depigmentation effects would not occur; the report reviewed genotoxicity, carcinogenicity (animal oral and dietary studies), and skin sensitisation data. 19
- Source EU SCCS (SCCS/1637/21, 2022) concluded kojic acid is safe for use as a skin-lightening ingredient at concentrations up to 1% in face creams (leave-on), face wash/cleansing products, and body lotions, after reviewing the full carcinogenicity and sensitisation data package. 18
- Study 5 of 8 patients using kojic acid skin care products tested positive on patch testing; facial allergic contact dermatitis developed after 1–12 months of product use — establishing kojic acid as a bona fide contact allergen. 10
- Study Allergic contact dermatitis from kojic acid was documented in a case series with positive patch test reactions; the authors note the ingredient's increasing cosmetic use as a whitening agent increases exposure risk. 11
- Study Pigmented contact dermatitis (paradoxical post-inflammatory hyperpigmentation) was reported as a side effect of kojic acid use — a clinically important paradox for a skin-lightening agent. 12
- Study Oral administration of 1.5–3% dietary kojic acid for 20 months induced thyroid follicular adenomas in 65–87% of male mice vs. 2% in controls; the mechanism is non-genotoxic and dose/threshold-dependent. 13
- Study Kojic acid showed no carcinogenic activity and no photo-genotoxic potential in mouse skin at topically relevant exposures — the key exonerating study underpinning regulatory acceptance for topical use. 17
- Study Non-genotoxic mode of action and a threshold for hepatocarcinogenicity of kojic acid were established in F344 rats — supporting a safe-level margin for topical exposures that produce low systemic absorption. 16
09 / The limits of the evidence
What we don't know yet
Most of what you read about this ingredient is stated with more certainty than the evidence earns. Here is exactly where the record thins out — so you can weigh the claims above for yourself.
- The classic mechanism paper (Cabanes et al. 1994, DOI:10.1111/j.2042-7158.1994.tb03741.x) is not indexed in PubMed/MEDLINE for this journal issue; the record was confirmed via Oxford Academic but no PMID exists.
- Direct head-to-head RCTs comparing kojic acid monotherapy to hydroquinone monotherapy at matched concentrations in the same patient population are limited; most comparison data comes from combination formulations.
- Kojic dipalmitate's in vivo conversion rate to free kojic acid in human skin has not been quantified in independent peer-reviewed literature; efficacy claims for KDP rely primarily on in vitro tyrosinase inhibition and formulation studies.
- The SCCS/1637/21 opinion applies specifically to kojic acid (free acid); the ester derivative kojic dipalmitate has not been separately reviewed by SCCS and is not covered by the 1% concentration limit (or the affirmative safety conclusion).
- Long-term (>3 month) clinical data on kojic acid monotherapy for hyperpigmentation is sparse; maintenance and recurrence rates after discontinuation are not well characterised.
- The sensitisation rate of kojic acid relative to other brighteners (niacinamide, alpha-arbutin, azelaic acid) in a controlled, powered, comparative patch-test study has not been published; the 'higher sensitisation' characterisation is based on case series and the frequency of reported reactions rather than a formal comparative HRIPT.
- Systemic absorption from topical 1% kojic acid in humans (which underpins the SCCS margin of safety calculation) is modelled rather than directly measured in well-designed pharmacokinetic studies.
- The CIR amended safety assessment (2025, issued for public comment) reached an insufficient-data determination; the final outcome and any updated concentration guidance had not been published as of the date of this dossier.
10 / What people say
What formulators and users say
What works
- Common One of the most potent OTC tyrosinase inhibitors — more direct mechanism than arbutin or niacinamide for stubborn hyperpigmentation 146
Kojic acid blocks the UV activation of tyrosinase, thereby limiting melanin production — Dr. Y. Claire Chang, board-certified cosmetic dermatologist Dermatologist
- Common Clinical trial evidence for melasma and post-inflammatory hyperpigmentation — 58% MASI reduction at 12 weeks in a randomised trial 32
Kojic acid has clinical evidence for measurable improvement in melasma at 1% over 12 weeks Dermatologist
- Common Effective on the hardest-to-treat spots — melasma, post-acne marks, and sun damage — where gentler brighteners often plateau 1derm ↗
Kojic acid is excellent at fading hyperpigmentation and discoloration — it is a safe brightening ingredient for all skin types and tones Dermatologist
- Common Available OTC in serums, creams, and soaps — accessible alternative to prescription hydroquinone for at-home treatment 31
Serums should contain 1-2% kojic acid for optimal brightening results Editorial
- Common Pairs synergistically with vitamin C, niacinamide, glycolic acid, and tranexamic acid — combination brightening formulas amplify results 15
dermatologists often recommend using it alongside vitamin C or niacinamide for a gentle, balanced approach to brightening Dermatologist
- Some Mild antimicrobial and antifungal properties — secondary benefit for acne-prone skin alongside brightening action 27
May help fight certain bacterial strains and may be useful for treating acne Editorial
What to know
- Common Higher sensitization and contact dermatitis risk than gentler brighteners — allergic reactions documented within 1–12 months of use in a subset of users; patch test is mandatory 491
Kojic acid is very irritating and is a potential allergen — often combined with a corticosteroid to reduce the chances of a reaction Editorial
- Common Oxidative instability — products turn yellow then brown when exposed to light, air, or iron; a discoloured kojic acid product has degraded and should be discarded 5610
Store at vampire conditions, and when it gets about 3 shades darker or even black… it's time to let it go Editorial
- Some EU and UK regulatory ceiling of 1% in leave-on face and hand products — narrows the formulation window and limits concentration above what some markets allow 810
Regulation (EU) 2024/996 added kojic acid to Annex III as a restricted substance at 1% maximum in face and hand products — effective April 23, 2024 Editorial
- Common Not for sensitive, eczema-prone, or rosacea skin — can worsen inflammatory conditions and increase irritation where the skin barrier is compromised 37
Those with underlying inflammatory conditions like eczema or rosacea may want to avoid kojic acid, as it could worsen inflammation Dermatologist
- Common Increases photosensitivity — reduces melanin production that normally buffers UV exposure, so skipping sunscreen while using kojic acid can worsen the very spots you're treating 27
Long-term use may increase susceptibility to sunburn — because kojic acid reduces melanin production, it also reduces your skin's natural UV protection Editorial
What you'd only know from the reviews
-
Kojic dipalmitate is a more stable ester form that does not discolour on oxidation — but its conversion to free kojic acid in skin requires esterase hydrolysis and that conversion rate in human skin in vivo is not well characterised. Choose KDP for shelf stability; accept that the clinical evidence base is thinner than for free kojic acid, and that the EU SCCS 1% limit applies only to the free acid. 1011
-
Soap-format kojic acid is beloved on Reddit and widely sold (Kojie San, Koji White), but it is the least effective delivery vehicle — short contact time as the lather washes off limits meaningful skin penetration. Serums and leave-on creams at 1–2% have the clinical evidence; soaps do not. The upside: the brief contact time does reduce irritation risk for sensitive users who would react to a leave-on. 53
-
Both kojic acid and vitamin C (L-ascorbic acid) target the copper site of tyrosinase — they have mechanistic overlap. Pairing them can amplify brightening but also combines two unstable, irritation-prone actives in one routine. If you're using both, packaging matters doubly: kojic acid browns on oxidation, vitamin C turns orange-brown; the same opaque, airtight bottle discipline applies to both. A formulation combining them needs especially robust antioxidant protection. 101
-
Opaque, airtight packaging is not a marketing feature for kojic acid — it is a functional requirement. Free kojic acid is oxidised by light, dissolved oxygen, and trace iron; once it turns yellow or brown, the tyrosinase-inhibiting activity has declined. A product in a clear glass dropper bottle with kojic acid is likely degraded by the time you're halfway through. The visual check: fresh kojic acid serums should be colourless to pale yellow; discard at brown. 510
-
Kojic acid should not be relied on as a solo active ingredient — it works best anchored in a multi-brightener formula (e.g., with niacinamide, tranexamic acid, or glycolic acid) because each agent attacks a different step of melanogenesis. Monotherapy also increases sensitisation risk from repeated high-concentration exposure without the buffering of complementary lower-concentration actives. 53
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
11 / Questions
Frequently asked
- What does kojic acid do for skin?
- Kojic acid inhibits tyrosinase — the enzyme that produces melanin — by chelating the copper ions at its active site. This reduces melanin synthesis and, with consistent use, visibly fades dark spots, melasma, and post-inflammatory hyperpigmentation. At 1–2%, it has clinical trial evidence for measurable improvement in melasma at 12 weeks (Deo 2013, PMID:23918998; Lim 1999, DOI:10.1046/j.1524-4725.1999.08236.x). It is also used in combination brightening serums with niacinamide and tranexamic acid (PMID:34962047). 234
- Is kojic acid safe?
- At 1% in leave-on products, the EU SCCS (SCCS/1637/21, 2022) and CIR (2010, PMID:21164073) both conclude it is safe for cosmetic use. The two real safety considerations are: (1) Contact sensitisation — kojic acid has a higher sensitisation rate than gentler brighteners; patch test studies found allergic reactions in a subset of users (PMID:7720390, PMID:9746193), and paradoxical pigmented contact dermatitis has been reported (PMID:20136888). (2) Carcinogenicity discourse — animal oral studies at very high dietary doses found thyroid and liver tumours (PMID:9734720, PMID:21112367). However, these effects are non-genotoxic, dose-threshold dependent, and topical application at 1% produces low systemic exposure. Mouse skin topical studies found no carcinogenic or photo-genotoxic activity (PMID:17538239). The SCCS reviewed all this data and reached a positive safety conclusion for 1% topical use. 18191011121317
- Kojic acid vs. hydroquinone for dark spots — which is better?
- Hydroquinone (HQ) at 2–4% is generally considered the reference standard for topical hyperpigmentation treatment with a longer evidence record. Kojic acid at 1–2% is a meaningful alternative, particularly as an adjunct to HQ: a split-face RCT found that adding kojic acid to a HQ + glycolic acid gel improved clearance from 47.5% to 60% (Lim 1999, DOI:10.1046/j.1524-4725.1999.08236.x). As a standalone alternative, kojic acid is clinically active (Deo 2013, PMID:23918998) but few well-powered direct head-to-head monotherapy trials exist. HQ has more regulatory restrictions and long-term use concerns (ochronosis at high chronic use); kojic acid's main drawback is sensitisation risk. Neither is universally superior — combination use is a common and evidence-supported approach. 32
- Kojic acid vs. vitamin C for brightening — how do they compare?
- Both inhibit tyrosinase but through different mechanisms and with different formulation constraints. L-ascorbic acid requires pH below 3.5 for meaningful skin penetration; kojic acid does not have this constraint and is formulated at mildly acidic to near-neutral pH. Vitamin C also has significant antioxidant and collagen-synthesis evidence that kojic acid lacks. There are no well-powered head-to-head clinical trials comparing the two as brightening monotherapies in the peer-reviewed literature. They are frequently combined (along with niacinamide and tranexamic acid) in multi-brightener formulations on the evidence that they act on different steps of the melanogenesis pathway. 4
- Why does my kojic acid product turn brown or yellow?
- Kojic acid is unstable in aqueous solution and oxidises on exposure to light, air (dissolved oxygen), and particularly iron ions (Fe3+). The iron-catalysed oxidation produces yellow-to-brown coloured chelate complexes — a visible sign of chemical degradation and potency loss (PMID:35620332). This is analogous to L-ascorbic acid serum turning orange-brown. A discoloured kojic acid product has degraded and should be discarded. Preventing it requires opaque, airless packaging; exclusion of iron-containing ingredients or processing equipment; and mildly acidic pH. Microemulsion and emulgel formats significantly improve photostability (PMID:15131725). 67
- What percentage of kojic acid is effective?
- Clinical evidence supports 1–2% as the effective range. Deo et al. (2013, PMID:23918998) demonstrated a 58% MASI reduction with 1% monotherapy at 12 weeks. Lim (1999) used 2% in combination with other brighteners. The EU SCCS caps leave-on products at 1% (SCCS/1637/21) on safety grounds. There is no published evidence that concentrations above 2% produce meaningfully greater brightening in humans, and higher concentrations increase the risk of contact sensitisation. 2183
- Is kojic dipalmitate the same as kojic acid?
- Kojic dipalmitate (KDP) is the dipalmitoyl ester of kojic acid — more stable, does not discolour on oxidation, and is lipophilic. It must be hydrolysed by skin esterases to release free kojic acid before it can inhibit tyrosinase. How efficiently this conversion happens in human skin in vivo is not well quantified. KDP is widely used in marketed products because of its stability advantage, but it has substantially less clinical trial evidence than free kojic acid itself, and it is not covered by the SCCS/1637/21 opinion (which applies to kojic acid only). Choose KDP for stability; accept that the efficacy evidence base is thinner. 9618
12 / References
Sources
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19