Other ingredient
Menadione
Menadione (Vitamin K3) is a synthetic 1,4-naphthoquinone — the unsubstituted quinone core of the vitamin K family. Unlike K1 and K2, it lacks the side chain required for biological coagulation activity. Its primary cosmetic function per EU CosIng is 'masking'; no SCCS or CIR safety opinion validates cosmetic skin benefits. It is a confirmed GHS Category 1 skin sensitizer (H317) and a redox-cycling pro-oxidant that generates reactive oxygen species. The Menadione + Ascorbic Acid combination is cytotoxic via ROS amplification (used in oncology as Apatone) and should not appear together in skincare.
Also known as: vitamin K3, 2-methyl-1,4-naphthoquinone
masking
Watch for
- ⚠GHS Category 1 skin sensitizer (H317) — allergic contact dermatitis documented in patch testing at concentrations as low as 0.01%
- ⚠GHS Category 2 skin irritant (H315)
- ⚠Pro-oxidant quinone: undergoes redox cycling generating reactive oxygen species (ROS); cytotoxic at higher concentrations
- ⚠Eye irritant — GHS Category 2A (H319)
- ⚠Combination with Ascorbic Acid produces a cytotoxic pro-oxidant ROS system; unsafe in cosmetics
- ⚠EU CosIng lists only 'masking' as its function — no SCCS or CIR safety opinion endorses cosmetic benefits
Compatibility
× Use with care
× Ascorbic Acid