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Retrieval-Augmented Generation for Reducing Hallucinations in Drug-Related Question Answering Systems

Kumar P, Verma R

2026

Abstract

Abstract Large Language Models (LLMs) deployed in pharmaceutical question-answering applications frequently generate clinically dangerous hallucinations — factually incorrect outputs that pose serious patient-safety risks. We propose and evaluate a Retrieval-Augmented Generation (RAG) pipeline that grounds LLM responses in a curated, citation-verified pharmaceutical knowledge base. The system combines dense passage retrieval using Sentence-BERT embeddings, FAISS vector indexing, cross-encoder re-ranking, and Llama 3.2 generation. Evaluated on a purpose-built dataset of 150 drug-related question–answer pairs spanning ten commonly used medications and multiple information categories, our RAG system reduces the hallucination rate from 47.8% to 12.3% — a 74.3% relative reduction — while improving Faithfulness from 0.52 to 0.87 and Factual Accuracy from 0.54 to 0.89. A clinical case study on warfarin–ibuprofen interaction demonstrates that RAG responses provide verifiable, citation-grounded information where the baseline produces potentially life-threatening misinformation. These results establish retrieval-augmented architectures as the preferred approach for safety-critical pharmaceutical AI and provide an open, reproducible evaluation framework.

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