Before you start

This is a short book and you can read it in two or three sittings. It's about one habit. You notice something in your body, such as a twitch, a headache or a mole you hadn't seen before. You pick up your phone to find out what it is. An hour later you're still reading, and you're more frightened than when you started. You put the phone down at last, and you've settled on the worst explanation you found.

I'm going to argue three things. The first is that searching makes sense from the inside. It's quick and private, and it feels like the responsible thing to do. The second is that a search can't do what you're asking of it. It can't examine you, so it can't tell you what you have, and it can't rule anything out. It does calm you, briefly, and then the worry comes back stronger. Left to itself, a search tends to end at the frightening answer, for reasons that have little to do with your body. The third is practical. When a symptom worries you, you look once, at one trusted page, to find out what to do. Then you do it, and you put the search down. Chapters 15 to 17 cover how.

This book contains no medical advice of its own. It can't tell you whether your symptom matters, and it won't try. Every statement about health in it comes from the NHS or from a paper named in the notes.

Four cautions.

If you think you or someone else may be seriously ill or in danger right now, don't read this book and don't search. Call 999. If you need help urgently and it isn't an emergency, call 111 or use 111 online.

Nothing in this book is a reason to stay away from a doctor. The argument runs the other way. Most of what you're trying to get from a search can only come from a person who can examine you. If a symptom is worrying you, a GP, a pharmacist or 111 is the right place to take it, and searching often delays that.

If worries about your health have started to take over your life, that has a name, and it can be treated. The NHS describes health anxiety as spending so much time worrying that you're ill, or going to get ill, that it starts to take over your life. Its advice is to see a GP if your worries are preventing you from leading a normal life or if self-help isn't working. Chapter 18 says more.

And if you live with a diagnosed condition, some of your looking up is part of managing it. This book isn't about that. It's about searching a new symptom, late, alone, until you're frightened.

The notes at the back give my sources and their limits. Where I'm giving my own reasoning and not a finding, I'll say so.