Both type I and type II varieties of complex regional pain syndrome share a common diagnostic criteria. They both consist of having a spontaneous onset of pain that is not limited to the distribution of a single nerve, a history of edema, or abnormal sweating. The only difference lies in the nature of the inciting event.

CRPS types I and II share the common diagnostic criteria shown below.

1. Spontaneous pain or allodynia/hyperalgesia is not limited to the territory of a single peripheral nerve, and is disproportionate to the inciting event.
2. There is a history of edema, skin blood flow abnormality, or abnormal sweating in the region of the pain since the inciting event.
3. No other conditions can account for the degree of pain and dysfunction.

The two types differ only in the nature of the inciting event. Type I CRPS develops following an initiating noxious event that may or may not have been traumatic, while type II CRPS develops after a nerve injury.