Glabridin is a flavonoid isolated from the root extract of Glycyrrhiza glabra (licorice). Its use in supporting or treating age spots (also known as hyperpigmentation or lentigines) is primarily supported by scientific studies rather than traditional use. Multiple in vitro and ex vivo studies have demonstrated that glabridin exhibits strong inhibitory effects on tyrosinase, the key enzyme involved in melanin biosynthesis. By suppressing tyrosinase activity, glabridin reduces melanin production in skin cells, which is the main mechanism underpinning its skin-lightening and anti-age spot properties.

Additionally, some clinical trials and cosmeceutical formulations containing glabridin have shown efficacy in reducing hyperpigmented lesions and improving overall skin tone. However, most published studies are small, short-term, or use mixtures of ingredients, making it difficult to isolate glabridin's sole effect. Safety data are generally favorable, with a low incidence of adverse effects when used topically.

In summary, the use of glabridin for age spots is grounded in solid mechanistic evidence and supported by early human data, though large, well-controlled clinical trials remain limited. Therefore, the evidence level is moderate (3/5).