Acute pain is an unpleasant sensation triggered in the nervous system to alert you that something’s wrong with your body, and that you need take care of yourself. Sometimes, acute pain becomes chronic and persists for months or even years. In many instances, this happens because your physiological condition is ongoing and unresolved, for example if you have arthritis. However, often the pain doesn’t appear to be caused by any disease, injury or detectable damage to the nervous system.