An antidepressant is a medicine doctors give for depression — a mental illness that can make a person feel hopeless, empty, or unable to enjoy things for a long stretch, not just a sad week. The name says against depression, and that is the main job it was named for. Though actually doctors also use some of these medicines for anxiety, for looping unwanted thoughts, or for certain kinds of pain, so the tidy name is narrower than real use. They are not sleeping pills, not calm-you-down drinks, and not a switch that turns a mood on the same day. They work slowly, often over a few weeks, by changing how chemical messengers in the brain are used. Some people talk loosely about happy pills. That phrase is unkind and untrue: the medicine does not manufacture happiness, and it is not a one-swallow cure. People may take it for a while and then stop with a doctor's help, or they may need it longer. That is a medical decision, not a moral one.