Complex regional pain syndrome type 1 (CRPS1) is a form of complex regional pain syndrome in which the pain is disproportionate to any known inciting event and is characterized by continuous pain, allodynia, or hyperalgesia as well as edema, coloration (changes in skin blood flow), or abnormal sudomotor activity in the region of pain. Onset of CRPS1 symptoms may occur within a few days to a month after an injury or trauma to the affected limb.