Skip to content
Submit incident
AII-1002-00223
ConfirmedA court, a regulator or the organization itself has stated the core facts, or the record cites a court or regulator source.

LLMs Give Unsafe Medical Advice Due to Typos and Informal Language

MIT researchers found that large language models deployed to make treatment recommendations are susceptible to nonclinical formatting and language variations in patient messages, sometimes recommending patients self-manage conditions when they should seek medical care. The effect is more pronounced for female patients, resulting in erroneous advice that avoidance of care is appropriate.

23 June 2025 Β· Reliability and hallucination
23 June 2025
AII-1002-002236 sources ↓
Quick facts
Category
Reliability and hallucination
Country
United States
Source
Medical Xpress - Medical and Health News
Date
23 June 2025
Drafted by
Raidu Incident Detection

What happened

MIT researchers studied how large language models (LLMs) deployed to make treatment recommendations respond to nonclinical information in patient messages, such as typos, extra white space, missing gender markers, and informal language.

The researchers found that making stylistic or grammatical changes to patient messages increases the likelihood an LLM will recommend self-management rather than an in-person appointment, even when medical care should be sought.

Reported impact

Nonclinical text variations were more likely to change treatment recommendations for female patients, resulting in a higher percentage of women receiving erroneous advice to avoid seeking medical care, according to human doctors.

The findings indicate LLMs used for treatment recommendations already deployed in health care facilities are affected by text formatting and linguistic choices unrelated to clinical content.

Index analysis

LLMs deployed to draft clinical notes and triage patient messages in health care facilities around the globe use nonclinical information for clinical decision-making in previously unknown ways.

The researchers note these models are trained and tested on medical exam questions but then used for different tasks such as evaluating the severity of clinical cases, with limited understanding of how LLMs perform in such settings.

Governance controls

The researchers state that models must be audited before use in health care, calling for more rigorous studies of LLMs before deployment for high-stakes applications like treatment recommendations.

Classification

Category
Reliability and hallucination
Industry
Healthcare, drugs and biotechnology
Country
United States
Harm status
Potential harm
Intent
Unintentional
Timing
Post-deployment
Harm types
Public interest
Harmed
Consumers, Women
Failure modes
Biased model, Agent misaction, Unsafe recommendation
AI systems
GPT-4

Sources and evidence

This record was researched and written by the Index, based on the following original reporting.

Medical Xpress - Medical and Health News
Typos and slang in patient messages can trip up AI models, leading to inconsistent medical recommendations
23 June 2025
Massachusetts Institute of Technology
LLMs factor in unrelated information when recommending medical treatments
23 June 2025
Scienmag: Latest Science and Health News
LLMs Integrate Irrelevant Data When Suggesting Medical Treatments, Study
23 June 2025
Mirage News
LLMs Weigh Irrelevant Data in Treatment Advice
23 June 2025
UPI
Slang, spelling errors derail AI in medical exams - UPI.com
26 June 2025
U.S. News & World Report
Typos, Slang Trip Up AI Medical Assessments
26 June 2025