Acute pain, for the most part, results from disease, injury to tissues, or inflammation.
Acute pain generally comes on suddenly, for example, after trauma or surgery, and may be accompanied by anxiety or emotional distress. The cause of acute pain can usually be diagnosed and treated. Acute pain is self-limiting, meaning, it is confined to a given period of time and severity. In some rare instances, acute pain can become chronic pain.
Chronic pain persists over a longer period of time than acute pain and is resistant to most medical treatments. It can and often does cause severe problems for patients, such as physical disability. Chronic pain can be made much worse by environmental and psychological factors.
Source: NIH Publication No. 01-2406, Pain: Hope Through Research, NINDS, December 2001