Treatments are designed to help people fight diseases or their symptoms, and they are supposed to make us feel better. However, some treatments can have unpleasant side effects. But did you know that we can sometimes feel side effects because we expect them to happen? Imagine that you have a cold and your parents give you a pill to help you get better. If they tell you that the pill could give you a headache, you might feel the headache coming on as soon as you take it—but if they had not told you, you might not have felt the headache at all. Such negative expectations are the driving force behind what is known as the nocebo effect. This article explains what the nocebo effect is, how it works, and how we can combat it.