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MedHallu: A Comprehensive Benchmark for Detecting Medical Hallucinations in Large Language Models

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arxiv 2502.14302 v1 pith:WJIXVSPO submitted 2025-02-20 cs.CL cs.AIcs.LG

MedHallu: A Comprehensive Benchmark for Detecting Medical Hallucinations in Large Language Models

classification cs.CL cs.AIcs.LG
keywords medicalhallucinationhallucinationsmedhallumodelsbenchmarkcategorydetecting
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
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Advancements in Large Language Models (LLMs) and their increasing use in medical question-answering necessitate rigorous evaluation of their reliability. A critical challenge lies in hallucination, where models generate plausible yet factually incorrect outputs. In the medical domain, this poses serious risks to patient safety and clinical decision-making. To address this, we introduce MedHallu, the first benchmark specifically designed for medical hallucination detection. MedHallu comprises 10,000 high-quality question-answer pairs derived from PubMedQA, with hallucinated answers systematically generated through a controlled pipeline. Our experiments show that state-of-the-art LLMs, including GPT-4o, Llama-3.1, and the medically fine-tuned UltraMedical, struggle with this binary hallucination detection task, with the best model achieving an F1 score as low as 0.625 for detecting "hard" category hallucinations. Using bidirectional entailment clustering, we show that harder-to-detect hallucinations are semantically closer to ground truth. Through experiments, we also show incorporating domain-specific knowledge and introducing a "not sure" category as one of the answer categories improves the precision and F1 scores by up to 38% relative to baselines.

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Forward citations

Cited by 7 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

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    cs.CL 2026-07 conditional novelty 6.0

    CLIR-Bench shows generalist and time-series LLMs struggle to ground clinical answers in sparse irregular ICU evidence, with top accuracy near 50% and weak causal evidence use.

  2. Graph Alignment Topology as an Inductive Bias for Grounding Detection

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    A GNN trained on bipartite alignment graphs between references and LLM generations reports state-of-the-art hallucination detection across four datasets, beating prior methods and GPT-4o.

  3. Hallucination Detection via Activations of Open-Weight Proxy Analyzers

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    A framework using activation-based features from small open-weight proxy models detects LLM hallucinations with higher AUC than ReDeEP on RAGTruth, performing consistently across seven analyzer architectures.

  4. A Multi-Stage Validation Framework for Trustworthy Large-scale Clinical Information Extraction using Large Language Models

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    A multi-stage framework with prompt calibration, rule-based filtering, semantic checks, judge LLM review, and predictive validation enables trustworthy LLM extraction of substance use disorder diagnoses from nearly 92...

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    cs.CL 2026-05 unverdicted novelty 5.0

    Med-HEAL builds a hallucination dataset from BioMistral answers on EHRNoteQA via GPT-4o and human review, then shows self-critique improves accuracy in three of five tested LLMs without retraining.

  7. MedFabric and EtHER: A Data-Centric Framework for Word-Level Fabrication Generation and Detection in Medical LLMs

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