Bad Influence: How the Internet Hijacked Our Health

by Deborah Cohen

You used to see a doctor. Now you go online.
'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 long waits for treatment and fewer face‑to‑face GP appointments, influencers have stepped into the breach. From doctors promoting untested therapies to celebrities selling solutions, these self-styled experts radiate wellness and guarantee results.

Exploring the transformation of a healthcare system driven by online trends, 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 we can no longer 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, Science, Health

430 pages, Kindle Edition

Published January 22, 2026

Reviews

[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.

[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.

[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!

[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.