To assess the potential risks associated with implementing large-scale language models (LLMs) in public health, we conducted focus group discussions with experts and practitioners on three key public health issues: infectious disease prevention (vaccines), chronic disease and well-being management (opioid use disorder), and community health and safety (intimate partner violence). Our findings led us to develop a risk classification framework that categorizes the potential risks associated with LLMs when used alongside traditional health communications across four dimensions: individual, person-centered care, information ecosystem, and technical responsibility.