Question: What is the best diagnosis code for allodynia? Oklahoma Subscriber Answer: Allodynia is characterized by the patient feeling pain caused by a stimulus that is not usually painful (such as light). Allodynia is covered by the more general term hyperesthesia, or an increased sensitivity. Your diagnosis options are: Note: Hyperalgesia is a condition sometimes tied to allodynia. Hyperalgesia is an increased response to a stimulus that normally is somewhat painful to begin with (such as a pin prick). You report hyperalgesia with diagnosis R20.8.