Acute pain is pain that comes on quickly and usually lasts a short time. It serves as a warning of injury or illness. Acute pain can range from mild to severe and is often caused by an injury or sudden illness. Examples of things that may cause acute pain include:

A broken bone
Dental work
Surgery
Childbirth
Burns and cuts
Gallstones
Chronic pain is defined as pain that lasts longer than 3 months. Some experts define it as lasting longer than 6 months.

Chronic pain is different than acute pain in that it is not easy to find the cause. Diagnosis can reveal no injury in the body at all, and yet the patient can be experiencing very debilitating pain.

One way that chronic pain begins is from an injury. Scientists have found that repeated pain from an acute injury changes the way the brain lets you know you have pain. Even after the injury has healed, pain messages replay over and over again.