How appropriate are ChatGPT-5's answers to acne questions?: A category-based evaluation by dermatologists

Online conversational tools have become increasingly common sources of health information, with many patients seeking acne advice through such platforms. Although they may enhance awareness and encourage early consultation, their medical reliability remains uncertain. Because acne is one of the most frequently searched dermatologic conditions, verifying the accuracy of automated responses is crucial to prevent misinformation. This study aimed to evaluate ChatGPT-5 responses to frequently asked acne questions in dermatology practice and to determine category-specific strengths and limitations based on blinded expert assessment. The analysis focused on identifying error patterns with potential implications for patient education and clinical safety. Twenty-five commonly asked patient questions were classified into 4 categories: skin care routine, nutrition and lifestyle, diagnosis and general information, and treatment and medications. Each question was entered into the publicly available ChatGPT-5 interface in 3 independent sessions, yielding 75 unique responses. Three dermatologists independently rated each response as "appropriate" or "inappropriate," and reasons for rejection were categorized using a predefined 9-item list. Of 75 responses, 49 (65.3%) were appropriate. Appropriateness was highest for skin care (83.3%) and nutrition (77.8%) and lowest for treatment (50.0%) and diagnosis (33.3%). Inter-rater agreement was low. The most frequent reasons for inappropriateness were misleading information and overly technical language, followed by lack of risk disclosure. ChatGPT-5 may provide helpful introductory information for patients; however, diagnostic and treatment guidance often lacked clarity and safety detail, underscoring the need for dermatologist oversight.