It is an unpleasant sensory and emotional experienced associated with actual or potential tissue damage, or described in terms of such damage.


It cannot be actually described as a sensory phenomenon, but it should be considered as a combination of:

- a perceptive part (nociception), representing the sensory response that allows the reception and transportation of potentially harmful stimuli to the central nervous system.

- a subjective part (therefore entirely private, an individual’s personal experience with pain), which is the psychological state related with the perception of an unpleasant sensation.


Pain is normal, a vital symptom, a defense system, when it represents an alert for a tissue lesion and it is crucial in order to avoid damages.
It becomes pathological when it self-maintains by losing its initial connotation and becoming a disease on its own (painful syndrome) impacting the subject’s quality of life.