Evaluation of the skin safety of a test product (sunscreen) for primary skin irritation using the skin irritation test (patch test in humans)

Objectives: The objective of this study was to evaluate the primary skin irritation potential of Venusia Sun Unseen Sunscreen, using a standardized human patch test. Materials and Methods: This was a monocentric, non-randomized, evaluator-blinded, single-application, controlled study conducted in accordance with IS 4011:2018 guidelines. Healthy male and female volunteers (18– 65 years, Fitzpatrick skin type III-V), including 50% classified as having sensitive skin, were included in the study. Occlusive patches containing Venusia Sun Unseen Sunscreen (~0.04 g), 0.9% isotonic saline (negative control), and 1% sodium lauryl sulfate (SLS, positive control) were applied for 24 h. The patch was removed at 24 h, scores were recorded at 48 h, and a follow-up visit was conducted 1 week later to verify the recovery of subjects who experienced local reactions. Skin reactions were graded using the Draize scale. Results: Twenty-six healthy adults (13 males, 13 females; mean age 30.88 ± 9.97 years), including 50% classified as having sensitive skin as identified by the lactic acid sting test, participated. All 26 participants completed the study. At 48 h, the sunscreen demonstrated a combined mean erythema/dryness/wrinkle plus edema score of 0.69, well below the IS 4011:2018 guidelines non-irritant threshold of 2.0. Saline produced no reaction (0.00), while SLS showed marked irritancy (3.04), validating assay sensitivity. No delayed reactions or adverse events were reported. Conclusion: Venusia Sun Unseen Sunscreen was classified as non-irritant under standardized patch test conditions in both sensitive and normal skin populations. These findings support its dermatological safety and reinforce its suitability as a daily-use sunscreen option that minimizes irritation risk while promoting adherence to photoprotection.