In the Federal Register of January 10, 2000 (65 FR 1399), FDA published a draft guidance entitled "Photosafety Testing." The notice gave interested persons an opportunity to submit comments. As a result of the comments, certain sections of the guidance were reworded to improve clarity. A final guidance was published in May 2003. The final guidance further emphasizes that a flexible approach can be used to address adverse photoeffects and that specific assays are not required. Moreover, it encourages the development of methods that can efficiently be used to evaluate human safety. The guidance describes a consistent, science-based approach for testing of topically and systemically administered drug products.