GPT-5.5 Instant is now on par with our frontier Thinking models for health-related questions. Every week, more than 230 million people turn to ChatGPT with health and wellness questions, and GPT-5.5 Instant is better at recognizing when urgent care may be needed, asking for relevant context, explaining uncertainty, and making complex information easier to understand. Because GPT-5.5 Instant is available to all free users in ChatGPT, these improvements can help more people. Physician-led evaluation was critical to making these major intelligence gains.