Glabridin

Glabridin is a licorice-root–derived flavonoid used mainly for brightening and anti-inflammatory effects, typically at low concentrations (about 0.1–1%) in leave-on products. While generally well-tolerated, botanical actives can trigger irritant or allergic contact dermatitis in a subset of sensitive or eczematous patients, and real-world formulations often pair it with penetration enhancers that can amplify reactivity. Given the potential for sensitization in compromised skin despite low typical dosing, a mild irritancy score is the safer clinical assessment. Safety Notes: In consumer leave-on brightening/anti-spot products, glabridin (typically as licorice extract standardized to glabridin) is commonly present at low active-equivalent levels around 0.01–0.10%, reflecting cost, solubility, and stability constraints; many mass-market serums/lotions fall in this band. Higher-strength OTC offerings (specialty hyperpigmentation serums/ampoules using purified glabridin or high-standardized extracts, often solubilized) reach ~0.5% and up to about 1.0% in real-world products marketed to the public. Rinse-off products tend to sit near the low end due to short contact time, while the upper end is primarily observed in leave-on treatments.