Depression can be short-term, lasting for just a couple of weeks, or long-term, lasting for years. It is normal to feel sad, lonely, or hopeless sometimes, such as after you experience a loss or during a time in your life when you are struggling. However, it is a problem when these feelings won’t go away, cause physical symptoms, or begin to interfere with your normal daily activities. If you think you might be depressed, it is important to seek medical help as soon as possible. Untreated depression may continue for months or years, and may even threaten your life.