Licorice root (Glycyrrhiza glabra) has a long history of use in traditional medicine, but its application for acne is primarily supported by emerging scientific evidence rather than tradition. The active compounds in licorice root, such as glabridin and liquiritin, exhibit anti-inflammatory, antibacterial, and antioxidant properties. These attributes are relevant to acne, which is characterized by inflammation and bacterial involvement (primarily Cutibacterium acnes).

Several in vitro and small-scale clinical studies have shown that topical preparations containing licorice extract may reduce redness, swelling, and bacterial load in acne lesions. For example, a 2010 double-blind study found that a topical gel with 2% licorice extract improved mild-to-moderate facial acne compared to placebo. Other research highlights licorice's ability to inhibit tyrosinase, which may help with post-acne hyperpigmentation.

However, the overall body of evidence is limited; most studies are small, short-term, or conducted in vitro rather than in larger human populations. As such, while there is some scientific rationale and preliminary evidence supporting licorice root's use for acne, it is not yet robustly validated, and more large-scale clinical trials are needed to confirm its efficacy and safety.