Work

An Investigator-Blinded, Randomized Trial of a Broad-Spectrum Sunscreen Containing Sclareolide and Niacinamide for the Prevention of Post-inflammatory Hyperpigmentation in Skin of Color

Year: 2025

Type: article

Study designs: Randomized Controlled Trial, Clinical Trial

Abstract: Post-inflammatory hyperpigmentation (PIH) is common and distressing in skin of color. Ultraviolet (UV) radiation and visible light (VL) exacerbate PIH, yet most sunscreens do not target the oxidative and inflammatory pathways that drive it. This study evaluated a broad-spectrum sunscreen with sclareolide and niacinamide for mitigating PIH induced by combined UV/VL exposure and inflammatory stimuli. In an investigator-masked, randomized, intra-individual study, 20 participants with Fitzpatrick skin types IV–V underwent controlled UV/VL exposure with or without tape stripping. The test product was applied daily for 20 days. The primary endpoint was change in ΔITA° at Day 22; clinical pigmentation/erythema and colorimetry (ΔL*, Δa*, Δb*, ΔE) were secondary endpoints. The sunscreen significantly prevented pigmentation at all protected sites. In stripped, exposed zones, protected skin improved by + 5.96 ΔITA° versus − 9.88 ΔITA° in unprotected skin (net protection ~ 16 ITA°, p < 0.001). In non-stripped, exposed areas, the difference was + 11.76 ΔITA° (p < 0.001). Secondary endpoints improved by 48–87%. No adverse events were reported. A broad-spectrum sunscreen with sclareolide and niacinamide mitigates PIH induced by inflammation and VL in darker phototypes. These findings support preventive use in PIH-prone populations. Comparative studies with and without these ingredients are warranted. This study was registered with ISRCTN under the identifier ISRCTN11448711. Post-inflammatory hyperpigmentation (PIH) is the darkening that can appear after acne, irritation, or procedures, and it often lasts longer and looks more noticeable in people with darker skin tones. Both ultraviolet (UV) and visible light (VL) can make PIH worse. Sunscreen helps, but most formulas are not designed to address the underlying triggers, such as inflammation and oxidative stress. In this study, we tested a broad-spectrum sunscreen that, in addition to UV/VL protection, contains two supportive ingredients: sclareolide (a plant-derived anti-inflammatory that may help reduce darkening) and niacinamide (a vitamin with well-known brightening and calming activities). Twenty adults with medium-to-dark skin (Fitzpatrick types IV–V) took part. Small test areas on the upper back were exposed to light, with or without mild skin barrier disruption, to mimic conditions that lead to PIH; the sunscreen was then applied daily. Compared with unprotected skin, areas treated with the sunscreen showed significantly less darkening and redness, with no side effects reported. These results suggest that a sunscreen containing sclareolide and niacinamide may help prevent dark spots that develop after inflammation and light exposure in people prone to PIH.

Source: Dermatology and Therapy

DOI: 10.1007/s13555-025-01586-w

Authors: Thierry Passeron, Anthony Brown, Marta Furmanczyk, Monica Foyaca, Carles Trullas, Jaime Piquero-Casals