“Don’t google your cancer,” the oncology nurse said to me as she drew my blood ahead of my first round of chemotherapy. It was 2006 and I was 17 years old. I was very confused by the emphasis she put on this advice. Still, I took the print-out of “safe” web addresses she gave me home and pinned it on the noticeboard in the kitchen, where it stayed, ignored, as I slowly progressed through six months of cancer treatment.

I was confused because the opportunities for me to use the internet to research my recent diagnosis of Hodgkin’s Lymphoma, a kind of blood cancer, were minimal anyway. I didn’t own a smartphone or a laptop and my only access to the internet was in communal spaces: at school or via my family’s shared computer with its dial-up connection. The notion that I could use these public facilities to explore something as intensely private as my cancer didn’t even register as a possibility for me.

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Everything changed a year later when I learned that the treatment had not been effective and the cancer was back. Or it had never gone away in the first place, it was hard to tell. Standing petrified in my college dorm room, I found the lump in my neck myself and its malignant properties were quickly confirmed by scans and tests. The chance of this happening, I was told by my doctors, was less than 5%. I had been “unlucky.”

Now, I was no longer a regularly supervised schoolgirl and I owned my own computer. I was free to look up symptoms and side effects and death rates as much as I liked. The medical professionals were doing their best with my case, but naturally they couldn’t give me absolute certainty about what was going to happen. Desperately craving some concrete information about my future, I kept searching and searching until I literally scared myself sick. I would have to snap the laptop shut and lie down until this internet-induced nausea passed, worn out from a rigorous schedule of in-patient treatments and college classes.

With hindsight, I can now recognize this as an early sign of the hypochondria that would become such a feature of my life in my 20s The popular conception of hypochondria, or health anxiety as it is often termed in the modern medical lexicon, is that it is rooted in ignorance. Unable to know the full scientific story about this suspected lump or that twinge of pain either because of a lack of access to healthcare or fear of what a doctor might say, the anxious brain writes in a narrative to explain it—usually one that involves the worst possible scenario and a terminal illness.

This idea of the hypochondriac’s ignorance being “cured” with knowledge is a very old one. As I delved deeper into the fascinating yet convoluted history of this condition with my own searches, I became preoccupied with the so-called “glass men”  of the middle ages, who experienced something called the glass delusion. Widely documented across Europe, these sufferers believed they were partly or wholly made of glass rather than human flesh, and the obsession with their fragile and breakable nature could come to dominate their whole life.

The 14th century French King Charles VI was a notable sufferer and in 1613 Cervantes published a whole novella about a “glass graduate” who experienced this. The treatment was simple: the “glass man” must be made to understand that he was not, in fact, made of glass. This was usually done by beating or squeezing him soundly until he acknowledged that he had not shattered into fragments. This proof, this extra knowledge of his resilience, would then cure him of the delusion.

But if hypochondria were truly cured by knowledge, advances in medicine would have made it a thing of the past. Yet anxiety disorders, including health anxiety, continue to be prevalent in countries with the most advanced healthcare systems. Hypochondria evolves and changes to keep pace with scientific knowledge. Where once people feared that they were made of glass or that an excess of black bile was making them melancholy, now they worry that they have brain tumours or long COVID-19. At every stage of medical progress, hypochondria is right there with us.

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Indeed, research shows that the prevalence of health anxiety is increasing among those who attend medical clinics—suggesting that more contact with medical knowledge is making our fears worse, rather than ridding us of them. This has been partly attributed to the rise of “cyberchondria,” in which anxieties about health escalate as a result of information found online. First used in the early 2000s, this word describes the pattern of excessive internet searching that I fell into after my cancer was declared cured, when my every twinge and sniff seemed to me to be a sign that the tumours were back.

I rationalized this behavior, as I think a lot of people with pre-existing conditions do, as simply being responsible or cautious about my health. Having already found a tumour once when my disease was supposed to be cured, I was hypervigilant against it happening again. Googling my every symptom and falling down a never-ending rabbit hole of research papers, online forums and wellness podcasts was just me being a good patient, I would tell myself.

It wasn’t excessive because I had such a complicated medical history. Doctors had told me to “keep an eye out” for possible symptoms and that was all I was doing. It took a lot of therapy and self-examination for me to realise that all of this extra information wasn’t affecting my medical outcomes positively at all: if anything, it was making me feel worse, not better.

Even with this awareness, it can be difficult to escape the clutches of cyberchondria. At times, it feels as though the whole internet is designed to magnify my fears. Typing “does headache mean…” into Google gives me, among others, the suggestions “miscarriage”, “concussion” and “brain tumour”, which are all rather more serious issues than the far more common and likely causes of “dehydration”, “stressed about work” and “lack of fresh air”.

The “escalation” mechanism that experts have identified as a tool in online political radicalisation operates in this field too. Just typing what feels like a mundane health query into a search engine can be the first step in a journey that leads to disinformation, self-diagnosis, and severe anxiety. Worse, there is evidence that the so-called “worried well”, with their health anxiety and their cyberchondria, can be up to 70% more likely to develop cardiac problems. All this worrying can make the worst happen, it would seem.

Knowing what I do now, I have immense respect for the foresight of my oncology nurse back in 2006. She said then that googling my cancer was a bad idea, and she was right, even though the true power of cyberchondria had not yet been unleashed by our constantly-online existence. The list of approved resources she gave me that day included only my healthcare provider’s website, a patient’s guide published by a cancer charity, a couple of online medical dictionaries and some academic publishers. This is what I restrict myself to today, even though sometimes my fingertips tingle with the desire to search more widely. I could click, and click, and click, until I am sick forever.