In This Book May Cause Side Effects, Dr. Helen Pilcher explores the "nocebo" effect—the shadow side of the placebo—and shows how our convictions can sometimes quite literally harm us.

Take the COVID vaccine. If you experienced side effects from your COVID vaccine, there is a 76 percent chance that these were caused by your belief that you would experience them—not by the mRNA circulating in your system.

Or, even more extreme, take the case of Sam Shoeman: Although his diagnosis of late-stage esophageal cancer turned out to be erroneous, he was nonetheless dead in months. The power of words, especially from health-care providers, is so formidable that even a wrong diagnosis can actually kill.

Our health, or lack of it, is as much about our expectations of illness and its causes as it is about damaged cells or wayward hormones. And because we can never fully step outside our cultural context, it’s only by understanding these effects that we can hope to prevent them.

From "hex deaths" to TikTok "illfluencers" to mysterious disorders with very real symptoms but no obvious physical cause, This Book May Cause Side Effects explores the many ways expectations can shape our health. Although the nocebo effect has always existed, the internet age has helped it spread faster than ever.

Thankfully, Dr. Pilcher also explains what we can do about it. She walks us through steps we can take individually and collectively to avoid invoking the nocebo, like reevaluating our relationship with technology, setting up risk-minimizing guidelines in health-care settings, and even crowbarring open-label placebo therapies and nocebo-blocking medicines into the pharmacological toolkit.

Smart, surprising, and full of unforgettable true stories, This Book May Cause Side Effects reveals the hidden ways our expectations influence our bodies—and what we can do to take back control.