Can coffee cause hallucinations or is it just latest headline scare?

by James Hubbard, M.D., M.P.H.

Have you seen the headlines? “Caffeinated co-eds hear voices,” “Heavy coffee drinkers more likely to hallucinate,” “Too much coffee can make you hallucinate and sense dead people say sleep experts. The equivalent of just seven cups of instant coffee a day is enough to trigger the weird responses.”  That’s about three cups of regular coffee per day.

It came to my attention when health writer Brian Newsome posted in the health blog of The Gazette, our local paper, “Move over LSD and step aside shrooms—Here comes coffee.” To his credit Brian was skeptical and, in fact, wrote a follow-up post with a link to Dr. Ben Goldacre, who criticized the study’s quality at his well-known website  (Dr. Goldacre evaluates the quality details of medical news, holding author’s and media reporter’s feet to the fire to get it right.)

Unfortunately, I don’t have access to the complete study, but after reading Dr. Goldacre’s critique, which I trust, it looks like a blatant example of why to take medical news headlines with a grain of salt until you know the details.

Summarizing Dr. Goldacre’s post, Drink coffee, see dead people, the problems included:

  1. It was a survey.  They’re never very accurate and depend completely on who responds and whether the responder understands and truthfully answers the questions.
  2. Questions included details about coffee drinking habits, and, as Dr. Goldacre put it:
    Some of these questions are about having hallucinations and seeing ghosts, but some really are a very long way from there. Heavy coffee drinkers could have got higher scores on this scale by responding affirmatively to statements like: “No matter how hard I try to concentrate on my work, unrelated thoughts always creep into my mind”; “Sometimes a passing thought will seem so real that it frightens me”; or “Sometimes my thoughts seem as real as actual events in my life”. That’s not seeing ghosts or hearing voices.
  3. The surveyors found the top 10 percent of heavy coffee drinkers answered yes to the following question three times more often than the bottom 10 percent: “In the past, I have had the experience of hearing a person’s voice and then found that no one was there.”
  4. Nowhere in the study do they specify the amount of coffee it took to increase hallucinations.  They just added the seven cups of instant coffee in the press release.
  5. Besides all the blatant problems above, their study proved only an “association” between hallucinations and increased coffee intake.  You should always view association studies with caution. For instance, people with hallucinations may just drink more coffee than the other way around.  Or maybe the coffee drinkers drank more alcohol, took more drugs, name it.  When you read that a study shows something is associated with something else, take note, but wait on further, more focused studies.  Most of the time you won’t hear much more because they will find it is just a coincidence.

Sometimes I just feel sorry for coffee, don’t you?  It needs to hire new PR.

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12 Responses to “Can coffee cause hallucinations or is it just latest headline scare?”

  1. Mark Salinas Says:

    I have a cup of coffee most mornings….No hallucinations here! :)

    “You should always view association studies with caution. For instance, people with hallucinations may just drink more coffee than the other way around. Or maybe the coffee drinkers drank more alcohol, took more drugs, name it.” <-Points that should be considered.

    Mark Salinass last blog post..Link Love Friday

  2. Steve Parker, M.D. Says:

    I hadn’t seen the headlines yet. I do notice wackier headlines on slow news days. The have to publish something, I guess.

    Steve Parker, M.D.s last blog post..“South Beach Diet” Review

  3. cathy Says:

    No coffee here – I just don’t like the taste – but it does all sound too sensational. But I might put this one away to use on my coffee drinking friends when I don’t agree with them – “You must be hallucinating!”

    Very nice look at the study, as always!

    cathys last blog post..Being a good guest when eating healthier

  4. James Hubbard, M.D., M.P.H. Says:


    I am not having hallucinations either, at least I don’t think so.

  5. Judy Rodman Says:

    If my Folgers is making me live with hallucinations, I don’t want to live in the real world :) hahaha!

    Judy Rodmans last blog post..Mindset for vocal breath : Support your intention!

  6. Brian Newsome Says:

    Health journalists are under a strain to crank out stories with their newsrooms growing emptier by the day, which leaves them more likely to rely on press releases that tout faulty, if flashy, science. Science and health is not the easiest beat to cover, and the crisis in media might affect health writing more than many other areas. Thanks, Dr. Hubbard, for noting this again (even if I initially drank the Kool-Aid, er, Starbuck’s Verona blend).

    Brian Newsomes last blog post..Monument girl will receive Medicaid for next transplant

  7. FatFighterTV Says:

    I am a health journalist/reporter and have worked in TV newsrooms across the country. I disagree that health journalists are more likely to rely on press releases that “tout faulty, if flashy, science” just because of the situation with smaller staffs. I think it has always (and still does) depended on the newsroom’s philosophy – some newsrooms like the flashy headlines; others won’t air anything unless it is truly worthy. Yes, often the sensational stories are there to get viewers. So I definitely agree – you do have to do your homework and go beyond the headlines.

    FatFighterTVs last blog post..Kellogg pulls peanut butter snacks over salmonella concerns

  8. James Hubbard, M.D., M.P.H. Says:

    Dr. Parker,

    I think you are right.

  9. James Hubbard, M.D., M.P.H. Says:

    Cathy, good excuse, at least.

  10. James Hubbard, M.D., M.P.H. Says:


    Who knows, you might be hallucinating this.

  11. James Hubbard, M.D., M.P.H. Says:


    Thanks for the good job you do.

  12. James Hubbard, M.D., M.P.H. Says:

    Thanks for your unique view, Cathy

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