Quick Comparison
| Licorice Root Extract | Vitamin K | |
|---|---|---|
| Typical Concentration | Concentrations vary; glabridin at 0.1-0.4% is the most active brightening component. Full extract at 1-4%. Apply morning and/or night. Safe for all skin types. Often combined with niacinamide and arbutin for enhanced brightening. | Concentrations: 1-5% in eye creams and targeted treatments. Apply to under-eye area and areas with visible blood vessels. Results take 4-8 weeks of consistent use. Phytonadione (vitamin K1) is the most common topical form. |
| Application | Topical (serum, cream, toner). Very stable in formulation. Compatible with most active ingredients. | Topical (eye cream, serum). Apply gently to under-eye area and areas of concern. |
| Research Papers | 10 papers | 10 papers |
| Categories |
Mechanism of Action
Licorice Root Extract
Glabridin competitively inhibits tyrosinase by binding copper active site (CuA, CuB), blocking tyrosine to L-DOPA hydroxylation and DOPA to dopaquinone oxidation. Also inhibits tyrosinase-related protein 1 (TRP-1). Liquiritin disperses existing melanin via melanosome transfer inhibition and autophagy pathway upregulation in keratinocytes. Glycyrrhizin inhibits COX-2 and 5-lipoxygenase, reducing prostaglandin and leukotriene production. Multi-mechanism brightening: tyrosinase inhibition, melanin dispersal, anti-inflammation. Unlike hydroquinone, no melanocyte cytotoxicity — suitable for long-term use and all skin tones. Glabridin has free radical scavenging antioxidant activity. Glycyrrhizin's 11-beta-HSD inhibition has minimal systemic effect with topical use.
Vitamin K
Vitamin K (phytonadione/K1) is cofactor for gamma-glutamyl carboxylase, which carboxylates glutamic acid residues in clotting factors II, VII, IX, X and proteins S, C — essential for calcium binding and coagulation cascade activation. Topically promotes reabsorption of subcutaneous extravasated blood by activating local clotting cascades that convert leaked hemoglobin to biliverdin and bilirubin for clearance. Strengthens capillary walls, reduces vascular permeability. For vascular dark circles: improves vessel wall integrity, reduces hemosiderin deposition. Supports elastic fiber production through matrix Gla protein carboxylation. Has anti-inflammatory effects. Clinical use: bruising, post-procedure ecchymosis, periorbital vascular hyperpigmentation. Results require 4-8 weeks consistent application.
Risks & Safety
Licorice Root Extract
Common
Very well-tolerated.
Serious
None documented topically. Oral licorice (glycyrrhizin) can elevate blood pressure, but topical use does not have this effect.
Rare
Allergic contact dermatitis.
Vitamin K
Common
Essentially none — very well-tolerated.
Serious
None documented topically.
Rare
Allergic contact dermatitis.
Full Profiles
Licorice Root Extract →
A natural brightening and anti-inflammatory ingredient derived from Glycyrrhiza glabra root. The key actives — glabridin, liquiritin, and glycyrrhizin — inhibit melanin production, reduce inflammation, and soothe irritation. Licorice root is one of the most effective and gentle brightening ingredients available, with lower irritation risk than vitamin C or hydroquinone.
Vitamin K →
A fat-soluble vitamin that supports blood clotting and blood vessel integrity. In skincare, vitamin K is primarily used for dark circles under the eyes (caused by visible blood vessels), bruising, spider veins, and post-procedure redness. It strengthens capillary walls and supports the reabsorption of blood that has leaked from damaged vessels. Often combined with retinol and vitamin C in eye creams.