Bad Influence: How the Internet Hijacked Our Health

by Deborah Cohen

You used to see a doctor. Now you go online.
SHORTLISTED FOR THE ROYAL SOCIETY TRIVEDI SCIENCE BOOK PRIZE

'Your definitive guide to separating medical facts from online fiction.' Adam Kay, author of This is Going to Hurt

'This superb book is an essential guide to the wild world of internet health.' Chris van Tulleken, author of Ultra-Processed People

Need to focus? Want to lose weight? Build muscle? Get pregnant? Advice is just a click away.

With GP appointments increasingly hard to access and treatment often slow to follow, influencers have stepped in to fill a very real gap, offering empathy, advice and solutions to the health questions we can’t afford to ignore.

Exploring the transformation of a healthcare landscape driven by algorithm, Dr Deborah Cohen reveals the truth behind Ozempic influencers, AI-powered diagnoses, ‘preventative’ screening and Instagram’s favourite wearable tech.

Bad Influence is about the commodification of health in an age of anxiety and why it’s so difficult to distinguish medicine from marketing.

'In a world where online medical opinions are fast and often dodgy, this is the perfect antidote.' Prof. Kevin Fong

Genres: Nonfiction, Health, Science, Technology, Medicine, Audiobook

430 pages, Kindle Edition

Published January 22, 2026

Reviews

[Jillian B · Rating 4 out of 5]

This is a guide to how medical misinformation spreads online, but the author doesn’t go for the low-hanging fruit. It’s not a book where readers get to feel superior to people who fall for stupid “miracle cures” and pseudoscience. Instead, it examines why so many people turn to social media for medical information and the effects it has on society. These issues get examined from all angles. For instance, when the author discusses the rise of anti-birth-control propaganda, she talks about the way it’s been spread by those with financial motive, but also why it is legitimately appealing to women who’ve had birth control side effects that were dismissed. She talks about the dangers of elective, preemptive full-body MRIs because they can spark panic over non-issues, but also talks to people who feel like they’ve been helped by them. We need more smart, nuanced books of this sort!

[Nathan Shuherk · Rating 4 out of 5]

Really feel like each chapter could’ve been its own book, and I’m sure they are, but I also think it helped to compile these case studies together because the meta narrative sometimes gets lost within each chapter.

[Keen Reader · Rating 4 out of 5]

CHOOSE YOUR PARENTS WISELY...

That would be my top health advice...Also don't forget to floss every day.

“The body is now a dashboard to be monitored and gamified.”

“But who’s tracking the trackers? Are they accurate?”

There’s always another space to occupy, commodify and profit from always another anxiety or insecurity to tap into, exploit and profit from. Celebrities, influencers, gurus – though I prefer the term bastards. Cohen has done a fine job of exploring the dark and ever shifting world of the disease mongering, data driven wellness culture, awash with diagnostic odysseys, content treadmills and generally awful people. There's even the occasional good egg in there, but usually being outshouted, outlied or outspent by the wrong uns.

“For patients, however, silence or vague reassurance can feel like indifference, especially in the face of persistent symptoms. The vacuum is where social media steps in, offering not only explanations but empathy, validation and a community of others who also feel unheard.”

“Social media is about certainty. ‘Social media has abolished doubt’.”

I was also intrigued by the concept of “borrowed legitimacy” which involves, “using credibility earned in regulated spaces to sell products in unregulated ones. This is how influence flows across platforms outpacing regulatory frameworks.” Also I laughed at how, “Sleep has become a competitive sport.” with one device described as “the latest totem of celebrity wellness culture.”

“The ‘Illusion of truth bias’ or the ‘illusory truth effect’: the more we see something, the more we believe it, regardless of whether it’s accurate. Our brains mistake familiarity for truth.”

[Gijs Limonard · Rating 4 out of 5]

solid 4 stars; as a practicing physician myself this was a welcome contemplation on the democratization of medical knowledge and to a certain extent, even medical practice; the general public has access to all relevant knowledge and can even organize some auto-treatment actions via the internet or by co-opting a compliant (or profit interested) doctor; whether people can make these health decisions by themselves; I have no doubt in many cases things kind of work out; but what to do about carrying responsibility for your actions? in most cases when things don't turn out for the best, or even cause serious harm; where to turn to but to the established medical order; interesting to see how this will play out in the years to come. For more on the subject of the use and abuse of medical knowledge, be sure to check out: Making Medical Knowledge, Bad Medicine: Doctors Doing Harm Since Hippocrates, Bad Therapy: Why the Kids Aren't Growing Up and out of the collection of my many favorites: How Doctors Think: Clinical Judgment and the Practice of Medicine, The Birth of the Clinic: An Archaeology of Medical Perception and Limits to Medicine: Medical Nemesis: The Expropriation of Health.

[Esther · Rating 2 out of 5]

I selected this book the moment I read the title. Even the blurb had me convinced it would be worth my time. I know the social media health world runs on stories and big emotions, not good research. So I was ready to dig in.

The author and I do not share a worldview. I am an American nurse and patient advocate. I believe every person is the CEO of their own health. They are responsible for building their care team, learning about their condition, and making their own decisions. I also value free speech and individual autonomy. The author writes from a UK, socialized medicine perspective. She believes government needs to control healthcare access and information because the average person might not choose wisely.

Most of my disagreements with this book trace back to that difference.

The author identifies real problems – the lack of nuance on social media, clicks driven by big transformations instead of balanced education, risks buried under inspiring stories. I agree with the problems. I disagree with her solutions. Over and over, her answer was more government involvement.

Take elective testing as an example. I teach my podcast listeners how to interpret their own labs and how to access testing outside their doctor or insurance when needed. Patient autonomy matters. Doctors are often hampered by insurance companies. Patients need options to fill the gap. The author sees that as a burden on the system. I see it as people advocating for themselves.

Her research was solid. The issues she raised are real. But free speech and patient/medial autonomy are not the problems here. More education is a better answer than restricting either free speech or autonomy.

[Cody Crawshaw · Rating 1 out of 5]

DNF at 100 pages. Just couldn’t get into it, often found it unnecessarily detailed on some studies that felt tangentially relevant, and then their linking explanation to the topic at hand was limited. Shame as I really wanted to enjoy this as it’s a fascinating topic!

[Sabrina · Rating 4.5 out of 5]

As someone working in a regulatory function for a social media company who also loves learning about all things fitness/health/"wellness," I was really excited to dive into this book and what I think is an incredibly urgent and contemporary topic. I'm pleased to say I truly enjoyed reading this, and that it did not disappoint!

The book is comprehensively and impressively well-researched, not only drawing on numerous scientific studies across a breadth of areas (ranging from weight-loss injectables and food allergen testing, to the rise in ADHD diagnoses and longevity (pseudo)science) but also going into the nitty-gritty granular details of what the methodological shortcomings or problematic financial incentives of each one are. Despite already having quite a bit of knowledge on how the platforms we use every day really work, I was still quite shocked to read about the lengths micro- and macro-influencers go to in order to sell or promote products that they themselves are not familiar with. I found mentions of the celebrity academics to be particularly troublesome in this regard; Huberman and Attia are idolized in popular circles and are given legitimacy due to their credentials and affiliations with high-profile universities, but even they are driven by commercial goals and making a quick buck at the end of the day. Cohen's methodical dissection of these figures and other "stars" in this space (such as Brian Johnson) I found to be really illuminating.

I'm knocking off half a star only because (and this is me being really picky!), I felt that each chapter was 75-80% diving into the various research studies of each health topic, and the relationship to how social media propels misinformation on these topics to be treated as somewhat of an afterthought. I also didn't really get a "prescription" for how we become a more informed consumer of this content, given how it's virtually unavoidable, short of doing deep levels of investigative research for any product or service that is marketed to us. I know how to scrutinize a message based on who is saying it to me and whether they're trying to sell something, but what more should I consider?

All in all, this was a useful reminder to remain vigilant and skeptical the next time (probably in the next five minutes) that I scroll TikTok and come across glow-up/get-hot-fast/this-is-the-best-thing-since-sliced-bread content.

[Katie · Rating 4 out of 5]

A really interesting book. Many of the people I work with have been taken in my influencer claims but I had no idea there was so much on socials about so many different health issues.
This book seems well researched and the author is transparent about the sort of studies and research that has been done (or not done) into these issues. She is balanced with her views on social media - that it can be helpful for people to find support, but it can also lead people to things that aren't so good for them. I enjoyed the chapter on ADHD and how many people are self-diagnosed thanks to long waiting lists, but also the chapters about people who have whole body MRIs or monitor their glucose for no reason. There was also an interesting chapter about HRT and hormonal contraceptives, so this book really does cover a broad range of health topics.
I always find the cult of influencers fascinating, and this is a cautionary tale about blindly listening to people online, and the moral questions about being paid in relation to a medical issue.

[Rachel · Rating 3 out of 5]

Got a bit boring toward the last third, but it was well researched. Good for reading if you've not already been exposed to the scamminess of it all that comes from social media via other sources (podcasts on the topic etc).

[David Margetts · Rating 4 out of 5]

A well written, well researched book that anyone with Instagram, Tik Tok, Facebook, X etc should read (but probably won't) The book covers one of the most important areas of our life, or health, which probably comes ahead of wealth and wisdom. This is not a new phenomena, we have always wanted to live longer, feel better, and look wonderful, and we have always been susceptible to 'quick fixes', 'easy solutions', and 'quack', yet in the 21st Century the Internet brings all of this to our screens at lightening speed and with incredible accessibility. The Internet should when it comes to information and facts in all aspects provide us with more data, greater accuracy, more objectivity, greater speed, improved transparency and greater expertise - in theory. In reality this book shows us that this is not always true and often the reverse. In our quest for better health, it now easier than ever for people to provide popular, quick and easy solutions at the click of a mouse. Where do these solutions come from? Well, you might think experts, regulated professions, or renowned institutions, doctors, specialists, consultants, psychiatrists, the NHS, the Government, Charities, NGO's etc But actually NO, as resources are more and more stretched and 'rationed' (post financial crisis and covid spending) people are tempted to turn to people they feel that they can 'trust', ie people like us, ordinary folk, who have lived experiences to share and who seemingly want to help. And maybe some do, but as the book exposes, these are not experts, they are not trained, they are not licensed nor regulated, and in most cases they are not objective. Many are driven by notoriety, fame, being respected, being liked, being popular, being 'experts', whilst many others are driven by money, commissions, sponsorship and gifts. So here it is, we are trusting people who are mostly not experts, and who are motivated to say what we want to hear and to promote products and solutions supplied by providers or their own companies. Sadly in so many examples our health is being hijacked and abused by such 'influencers' who make a living from the pain and discomfort of some of the most vulnerable in society. What I have learned from this excellent book is what most of us already know. If it too good to be true, then it probably is, there are no easy quick fixes when it comes to health, wealth or wisdom for that matter (unless you are a highly paid Influencer or won the lottery) and that if you want to be healthy, look good, and live long, then the best medicine is not supplements, surgery, or special treatments (expensive especially) but just 'eat well, sleep well, exercise well, and avoid tobacco, alcohol and drugs' - and that is mostly the cheapest and most effective option available! (But not the easiest one sadly)

[Library's Rat · Rating 1 out of 5]

The issue of multi-billion dollar companies taking over the public health discourse via social media platforms and impeding on NHS territory (including on the very slippery doctor/patient relationship) is indeed one worthy of a good, long book. If I appreciate the dedication Deborah Cohen put into this one, there were some serious limitations (and bias) that I feel should really be brought to light.

The author rightly points out how greedily companies approach patients online, often through the use of celebrities, to push a certain product or medical test. Most of which are deemed pretty useless by science, but even harmful at times as clogging the healthcare system and robbing patients of thousands of dollars (or more). I was glad to see the Kardashians (whose companies rate lower than Shein on the sustainability index...) and wellness gurus such as Paltrow called out.

However, there was a sense that the book was written not to foster a better, more joined up approach to care, but to boost doctors egos that they are usually right to dismiss patients who come to them with... well questions and concerns (and yes some dodgy test results). Patient centered care you say? Not so much here. This book gave me massive Scrubs' Dr Cox vibes: "JD, you need to remember that patients are scared and stupid".

I'm saying this as this book follows the very archaic, but incredibly (passively) useful to an over-streched NHS, narrative that when we don't know what's going on with patients we can easily put it down to anxiety and depression (like those are also symptoms where patients are supported, hey?). Given how much medical misogyny has historically harmed women, I find it hard to swallow that a woman would feed into such concepts without adding any nuance to it.

Tik Tok tics for instance. The author puts it down to teens being anxious. Yet, GOSH (https://www.gosh.nhs.uk/wards-and-dep...) found that a lot of those people were then diagnosed to be neurodivergent. Many neurodivergent people stim and copy others. But according to this book you'll just leave thinking 'man, people are so desperate for attention for their anxiety that they'll make themselves look ill!'. 'Not their fault! They're their worst enemy!"

It is worrying that this book feeds into the 'just anxious patient' narrative being replaced with the new 'anxious, but not their fault - they're so unaware of it poor things!' - and that this is almost presented as progress. And of course it's impossible to fight against such an argument as doctors will say it only confirms what they already presume (i.e. that patients overthinking their symptoms and trying to find a cause is the root of their symptoms). It is an incredibly condescending approach to medicine AND it is wholly unscientific too. I'd have loved to hear more about how scientifically robust the studies on the nocebo effects are for instance (as many other study designs were meticulously broken down by the author), and how this knowledge can be put into actual practice. There's a concern though that the more recent studies on nocebo effect, how much the brain can trigger pain signals etc. have translated, well, are stretched, to fit a narrative where doctors put a lot of the onus on subconscious responses and end up denying access to care to patients they deem too complex or too irrational. Where do we find a balance then? And why is this book completely ignoring this point? For more info on the complexity between body and mind I'd recommend the book 'It's All In Your Body' as it explores the dual connections between body and mind - as opposed to the overbearing 'it's all in your mind' (yes, that's why the title is so black and white!).

Let's go back to neurodivergence for a second though. Deborah Cohen makes claims not backed by the majority of studies, especially when it comes to the idea that 'many' people grow out of their ADHD. Most scientific studies have actually found that most people (usually around 60%) with ADHD do not grow out of it. But her claim is used to back up the fact that folks are over-diagnosed.

Over-diagnosed btw? Maybe this book should have touched on how the idea of people getting diagnosed is very inconvenient for both policy-makers and the NHS. Imagine having to support people properly through Access To Work and support with real NHS pathways that deal with more than just medication? Imagine the money spent? Better tell patients to chill the fuck out and deal with very normal behaviours that every human has (it's a spectrum folks, just go to sleep). It's not like many studies showed early diagnosis can save lives, marriages, jobs...

And yeah over diagnosis within the NHS let's talk about it more shall we? What about the plethora of diagnoses such as BPD, FND etc. (Dr O'Sullivan is a champion here, it's easier when the narrative is that people need to go away and deal with anxiety)? What about women being ignored for symptoms most men receive immediate care for? How can this book adopt very narrow views without looking at the overraching diagnosis system is beyond me.

This book should have touched upon how, based on what they're exposed to, both patients and doctors should try and work as a team. Otherwise it all feels very much like denouncing a problem and making patients the weak voice in the conversation. But it all reads very much like the author wants to comfort doctors in the knowledge that they're the voice of reason and... that's pretty much it.

This book should have also touched on the sensitive nature of scientific studies. If you don't ask certain questions or rather ask particular questions a certain way you can get the answers you sometimes want. Again, it felt like the author showed and shared what was convenient to make doctors feel safe in their usual 'Keep calm and carry on'.

Maybe the losers here are the patients. Stuck between predatory companies and (too often) gaslighting doctors. Maybe the losers are the patients who stop seeking answers. And show up to A&E months or years later. And the patients who keep seeking answers too. Because no one will listen. And they fall into the wrong hands. Or the patients with social issues (homelessness, DV, etc.) or issues like chronic pain who get booted out of the NHS and keep being told to see their GP only to fall between the cracks.

Maybe the issue here is that patients already have so little credibility when they enter the room. And they might have even less if doctors use this book to simply jump to the conclusion that they should stay away from the internet and stop "diagnosing themselves on the internet".

At a time when resources and time are so incredibly limited, let's not forget some doctors will end up getting stuck (consciously or unconsciously) into a hierarchy of access (only treating people you deem "the worst" to protect resources) and this book can help with just that. Let's remember the NHS was supposed to be free for all. And all should mean all.

[Peter Brown · Rating 5 out of 5]

Reading the penultimate chapter I had a thought: in olden times the general belief was that as long as you’d behaved a better life welcomed you in the hereafter. The rise of secularism leans us towards thinking it’s just ‘now’ so you’d better make the most of it, extend it and hopefully enjoy good health, maximize your benefits reach, reminding me of the Catholic church’s selling of indulgences to aid your passage in the afterlife. Now it’s eat this, take that, sign up and buy the goods and you can improve your earthly existence, even prolong it, the internet as a new religion. My hypothesis doesn’t pass muster as almost two thirds of Americans and half of Britons believe in life after death; hedging their bets? Pandora’s box has been opened and the snake oil merchants have their eye on your wallet via your body (body snatchers), though Deborah Cohen does point out that there’s good mixed in with the less good and quite frankly the extremely dodgy. Read this book and be amazed, more informed or dismissive; it a judicious sifting of what’s trending on the wild frontier!

This book cries out for an index.

[Chelly Hoffman · Rating 2 out of 5]

My biggest issue with this book is that it is largely one-sided. Which I guess is to be expected as it’s the point of view of a specific person. But just as social media tends to inflate certain things and generalize, the author is guilty of this as well.

One example is the part about IUDs. While it’s true that people are more likely to talk about negative experiences with a medical procedure, like IUD placement, that doesn’t mean that those experiences should be minimized. We still have doctors thinking that there are no nerve endings in the uterus and that you shouldn’t feel pain. If there are no nerve endings and you “shouldn’t feel any pain” during certain procedures then why are some of us feeling pain?? Misinformation online is a huge problem and I agree with that. But you know what else is a problem? The lack of research and funding into women’s bodies. And the dismissal of our pain from medical professionals. If anything, the conversation about IUD insertion and the pain associated with it leading to actual pain management solutions being offered to patients is nothing short of a miracle. And I found the author’s distain about this topic infuriating.

[Diana · Rating 2 out of 5]

I listened to this as an Audiobook & it took me almost a full month, although I'll admit the month was very busy. Out of curiosity I googled how many pages this is in print-- 384. I don't know if I would've stuck with all 384 pages if I'd had a paper copy. Probably would not have. 3 stars is my rating for an average book, nothing special. 4 stars is a good book. 5 stars is an amazing one. 1 star is crap. This was an easy 2 stars.

This book had good potential but the author dragged on and on. If this had been half the length it could've been a brilliant book. I liked how each chapter was about a different aspect of internet health topics (podcast bros and their obsession with testosterone, online fertility tracking/treatment companies that take advantage of women trying to conceive but have no science behind them, the obsession with GLP-1s, etc., etc.). I found the first 10 or so chapter topics interesting and then it just got boring. Alas I listened because I enjoyed the format of each chapter jumping to a slightly new topic and I needed something to listen to to pass the time.

[Niels Broekman · Rating 5 out of 5]

IJzersterk stuk onderzoeksjournalistiek. De auteur geeft context, beschouwt en schroomt vervolgens niet om conclusies te verbinden aan haar bevindingen. De boodschap van haar verhaal is helder: we moeten technologische determinanten van gezondheid serieus gaan nemen, met m.i. algoritme-stuurde verspreiding van desinformatie met stip op 1. Het werkt op een gevaarlijke manier een onjuist gevoel van overdreven maakbare gezondheid in de hand, want voor lang niet alles wat grotendeels online wordt aangeprezen geldt nog ‘baadt het niet, dan schaadt het niet’, laat de auteur aan de hand van verschillende voorbeelden zien. Door het geven van valse hoop en vercommercialisering van zorgen en angst, bestaat de groep die hierdoor het hardst geraakt wordt uit de vaak kwetsbare mensen wiens zorgen of klachten niet worden herkend in de reguliere gezondheidszorg.

[Megan · Rating 4 out of 5]

Some chapters were 5 stars, others were 3.
Some of my fave facts were as follows:
- britons have record low satisfaction with the NHS, and record high belief in its core mission
- breast implants can cause cancer (rarely)
- between 1964 and 2009, 25+ anti obesity drugs were withdrawn from the market for reasons such as psychoatric disturbances and cardiac toxicity
- 37% of tiktok users have bought medicine after seeing it advertised on tiktok
- less than half of ADHD tiktok vids are reflective of DSM5 symptoms, and nearly 70% of vids depicted symptoms than non ADHD people would have
- 36% of women who had an abortion said that inability to strong access contraception was a factor
- social relationships are associated with life expectance more than class, IQ, or genes

[Jessica · Rating 5 out of 5]

Really interesting, I’m afraid people who need to read it probably won’t.

I like how nuanced it is. Social media is not all bad, it can give people community or answers to people who feel failed by medicine. That being said social media is not where you will find the most accurate information. Most people are here to sell something (let’s be real), social media is also the place where actual science goes to die and personal anecdotes thrive.

It’s terrible (and I love that the author acknowledges that) that people who are being failed by the medical establishment are targets of people trying to make money. Social media and the art of influencing makes it so easy.

[Richard Smith · Rating 5 out of 5]

A very important book that identifies a change in health behaviour that is crucial but probably still at its beginning. People, particularly young women, find it increasingly difficult to access the NHS, and when they do they often find that they are not listened to, not taken seriously, and not given an explanation of or a treatment for their symptoms. They turn to social media and find there support, friendship, empathy, explanations, diagnoses, and even treatment. Some of what they find is reliable and useful but much of it is based on flawed science and commercially driven.

[Mayar Mahdy · Rating 3 out of 5]

3.5/5

Ironically, I read this because of a Tiktok recommendation.

It's well-written, so I didn't feel bored while reading it. I thought it was really interesting, and it managed to cover lots of aspects of alternative health practices. I especially liked how it presented both how well-known figures and micro-influencers contribute to this distrust of medical establishment and offer "alternative treatment methods." She also mentioned how some of these people are legitimate doctors yet give very concerning advice that's literally a thinly-veiled ad.

[John · Rating 5 out of 5]

excellent, concerning, thought provoking

[Eleanor · Rating 4 out of 5]

Marketing traps are just one of the many deceptions in this world.

[Ika Willis · Rating 2 out of 5]

TOO BORING