AI as a Post-Market Safety Channel: When Omitted Contraindications Become a Pharmacovigilance Failure

Public-facing AI assistants increasingly provide medication guidance to patients and caregivers prior to consultation with healthcare professionals or review of approved labeling. While much attention has focused on hallucinated or incorrect outputs, less attention has been paid to omission of safety-critical information that is present in approved product labeling. This paper argues that AI-mediated omission of contraindications constitutes a post-market safety risk that is currently under-monitored by pharmaceutical manufacturers. Using a reconstructed illustrative scenario, the paper demonstrates how Reasoning Claim Tokens (RCTs) can function as evidentiary artifacts to detect, document, and audit such omissions without requiring access to AI model internals or operational control over third-party systems. The analysis situates AI-mediated omission risk within existing pharmacovigilance doctrine and clarifies the governance implications of detectability, repeatability, and foreseeability. https://www.aivojournal.org/ai-as-a-post-market-safety-channel/