Have you ever found yourself staring at an online pharmacy checkout page, wondering if that new allergy medication plays nice with your daily vitamins? Polypharmacy is a silent risk, and while doctors are the experts, having a real-time browser-based agent as a second pair of eyes can be a lifesaver. In this tutorial, we’re building a Drug-Interaction Guard . This is a sophisticated LLM Agent that lives in your browser, scrapes medication names from your active tab, and cross-references them against your personal "current meds" list using the PubMed API and Tavily Search . We will leverage LangGraph to handle the complex reasoning loops required for medical safety checks. Whether you're interested in LangGraph agentic workflows , Chrome Extension automation , or AI-driven healthcare safety , this guide has you covered. The Architecture A simple chatbot isn't enough for this task. We need an agent that can reason: "I see Drug A on the page. User takes Drug B. Let me search PubMed for interactions.…