Regulatory Gap January 30, 2026 8 min read

Vitamin K3 (Menadione): The Ingredient Nobody Is Assessing

It's used in Korean skincare for skin brightening. It's a Category 1 Skin Sensitizer with genotoxicity concerns. And it has no SCCS safety opinion. How did menadione slip through the regulatory cracks?

Here's a regulatory paradox that should concern every cosmetic chemist and conscious consumer: Vitamin K1 (phytonadione) was banned from EU cosmetics after SCCS assessment found allergenic potential. Meanwhile, Vitamin K3 (menadione) - which has worse safety data - remains completely permitted without any formal safety opinion.

And it's already in products. Korean skincare brands like Sidmool, Some By Mi, and Dr. Jart+ have formulated with menadione for its skin-brightening effects. The science works. The safety assessment? It doesn't exist.

The Basic Facts

Parameter Menadione (Vitamin K3)
INCI Name Menadione
CAS Number 58-27-5
Function Skin conditioning, depigmenting
EU Status Permitted (no restrictions)
SCCS Opinion NONE
GHS Classification Category 1 Skin Sensitizer

The Vitamin K Paradox

In 2010, the SCCS issued opinion SCCS/1313/10 on Vitamin K1 (phytonadione). Their conclusion? Allergenic potential justified prohibition in cosmetics. The ingredient was added to Annex II of the EU Cosmetics Regulation - banned.

But Vitamin K3? Nothing. No mandate for assessment. No SCCS opinion. No CIR review. The ingredient sits in a regulatory blind spot.

The Safety Data Gap

  • No human dermal absorption study (OECD 428) published
  • No HRIPT data at intended cosmetic use concentrations
  • No Margin of Safety calculation possible without absorption data
  • UDS-positive genotoxicity (DNA damage via reactive oxygen species)
  • Category 1 Skin Sensitizer under GHS classification

Why Is It Being Used?

Menadione actually works for skin brightening - through a novel mechanism. Unlike typical depigmenting agents that directly inhibit tyrosinase, menadione inhibits melanin synthesis through ERK activation and MITF downregulation.

This different pathway makes it attractive for formulators looking beyond the usual suspects (hydroquinone, arbutin, kojic acid). Korean cosmetic innovation, which often leads global trends, has embraced it.

The problem? Benefits don't negate the need for safety assessment. And the safety data simply isn't there.

The Redox Cycling Problem

Menadione's mechanism is a double-edged sword. It works through redox cycling - the same mechanism that creates reactive oxygen species (ROS) at high doses.

At low doses, this creates protective effects. At higher doses, it causes oxidative stress and DNA damage. The UDS-positive (Unscheduled DNA Synthesis) finding in genotoxicity testing confirms this.

Without validated human dermal absorption data, it's impossible to calculate systemic exposure and determine what concentration is actually safe.

Who's At Risk?

Beyond general sensitization concerns, menadione poses specific risks to certain populations:

  • G6PD-deficient individuals (~400 million people globally) - can trigger hemolytic anemia
  • Individuals with existing skin sensitivities - Category 1 sensitizer status
  • Those using multiple brightening products - cumulative exposure unknown

The Regulatory Questions

This situation raises serious questions about how cosmetic ingredients get assessed:

  1. Why was K1 assessed but not K3? Both are Vitamin K forms used in cosmetics.
  2. Who triggers SCCS assessment? Does an ingredient need to cause harm before it's reviewed?
  3. What about emerging markets? Korean products with menadione are sold globally, including in the EU.
  4. Should GHS Category 1 sensitizers automatically require SCCS opinion?

What Should Formulators Do?

Recommendations

  • Avoid formulating with menadione until proper safety assessment exists
  • If using, conduct in-house safety testing including HRIPT at intended concentration
  • Document your safety rationale in the Product Information File
  • Consider alternatives like Vitamin K oxide (which has more data)
  • Watch for regulatory updates - this gap may close

What Should Consumers Do?

If you see "Menadione" on an ingredient list:

  • Patch test before full application, especially if you have sensitive skin
  • Avoid if G6PD-deficient or have a family history of favism
  • Be aware this ingredient lacks formal EU safety assessment
  • Consider asking brands what safety testing they've conducted

The Bottom Line

Menadione represents a gap in our regulatory system. An ingredient with concerning safety signals - Category 1 sensitizer status, genotoxicity findings, risks to vulnerable populations - is being used in cosmetics without the formal safety assessment we expect for such ingredients.

It may turn out to be safe at certain concentrations. But right now, we don't have the data to know. And that's exactly why SCCS assessments exist.

Until menadione receives proper evaluation, it belongs in the "proceed with extreme caution" category - for formulators and consumers alike.

References

  • SCCS/1313/10 - Opinion on Vitamin K1 (phytonadione)
  • EU Cosmetics Regulation 1223/2009
  • GHS Classification for Menadione - ECHA Database
  • CosIng Database - European Commission