From a neurologist and the award-winning author of The Sleeping Beauties, a meticulous and compassionate exploration of how our culture of medical diagnosis can harm, rather than help, patients. We live in an age of diagnosis. Conditions like ADHD and autism are on the rapid rise, while new categories like long Covid are being created. Medical terms are increasingly used to describe ordinary human experiences, and the advance of sophisticated genetic sequencing techniques means that even the healthiest of us may soon be screened for potential abnormalities. More people are labeled "sick" than ever before--but are these diagnoses improving their lives? With scientific authority and compassionate storytelling, neurologist Suzanne O'Sullivan argues that our obsession with diagnosis is harming more than helping. It is natural when we are suffering to want a clear label, understanding, and, of course, treatment. But our current approach to diagnosis too often pathologizes difference, increases our anxiety, and changes our experience of our bodies for the worse. Through the moving stories of real people, O'Sullivan compares the impact of a medical label to the pain of not knowing. She explains the way the boundaries of a diagnosis can blur over time. Most importantly, she calls for us to find new and better vocabularies for suffering and to find ways to support people without medicalizing them.