Acute pain begins suddenly and is usually sharp in quality. It serves as a warning of disease or a threat to the body. Acute pain may be mild and last just a moment, or it may be severe and last for weeks or months. In most cases, acute pain does not last longer than six months and it disappears when the underlying cause of pain has been treated or has healed. Unrelieved acute pain, however, may lead to chronic pain. Acute pain may be caused by many events or circumstances. These circumstances are explored below.