This was a single-center, evaluator-blinded, randomized, placebo (vehicle) -controlled phase I study to evaluate the photoallergic potential of Clindamycin-Tretinoin Gel. The design consisted of the following periods: screening, induction, rest, challenge, and rechallenge (if indicated). Induction visit 1 was to occur within 5 days of screening visit 2. The study expected to enroll approximately 62 healthy adult volunteers. Subjects were to receive repeated 24-hour study patch applications; after patch removal, the sites were irradiated with ultraviolet B light (UVB) and visible light (VIS) during the induction period (consisting of 6 consecutive induction phases), and ultraviolet A light (UVA)/ UVB and VIS during the challenge and rechallenge periods. Each application site was observed approximately 1, 24, 48, and 72 hours later for signs of inflammation.