Hyperalgesia is an extreme sensitivity to pain, which in one form is caused by damage to nociceptors in the body's soft tissues.

Hyperalgesia can be experienced in focal, discrete areas, or as a more diffuse, body-wide form. Conditioning studies have established that it is possible to experience a learned hyperalgesia of the latter, diffuse form. The focal form is typically associated with injury, and is divided into two subtypes:

• Primary hyperalgesia describes pain sensitivity that occurs directly in the damaged tissues.
• Secondary hyperalgesia describes pain sensitivity that occurs in surrounding undamaged tissues.

Hyperalgesia is induced by Platelet Aggregating Factor (PAF) which comes about in an inflammatory/allergic response.

One unusual cause of focal hyperalgesia is platypus venom.