When a peripheral nerve is irritated enough, it becomes hypersensitive to the noxious stimuli, which results in increased painfulness or hyperalgesia. Health care professionals recognize both primary and secondary forms of hyperalgesia. What is primary hyperalgesia?

Primary hyperalgesia definition:

This refers to a response or sensitivity to a stimulus which causes pain as one get injured at that instant as they experience the pain.

This occurs when someone get hit by something or they get burnt anything that causes pain on their tissues and the nerves secondary hyperalgesia is the further pain that exist after a person has been injured and the wounds haven't healed those pains that the person continue to feel on around their tissues is secondary hyperalgesia.