Acute pain has a distinct warning and protection function, since it is caused by external or internal injury or damage and the pain intensity correlates with the triggering stimulus. Acute pain is of short duration (defined as <3months). Patients can tolerate acute pain to a certain extent; however, inadequately treated acute pain is a risk factor for severe medical complications and for developing chronic pain.1-2

Chronic pain has lost its warning and protective function and exists uncoupled from the causative event. This means that the pain intensity no longer correlates with the causal stimulus. The pain has become a disease on its own and provides a special therapeutic challenge.3

The table below gives a brief overview about the differences between acute and chronic pain:4,5


Acute Pain Chronic Pain
Short duration Longer duration (>3 month)*
Physiological warning and protective function Has lost warning and protective function; is now a disease
Signals tissue damage Uncoupled from the causative event
Disappears when underlying cause of pain has been treated or has healed Intensity no longer correlates with the causal stimulus
Clearly located Cause may not be known

*this is the criterion used to define pain as ‘chronic’ 3



1Thomas MA. Pain management – the challenge. Ochner J 2003;15-21.
2 Wells N, Pasero C, McCaffery M. Improving the quality of care through pain assessment and management. In: Patient Safety and Quality: An Evidence-Based Handbook for Nurses. Ed: Hughes RG. Rockville, Maryland: Agency for Healthcare Research and Quality, 2008.
3 IASP, 1994. Part III: Pain Terms, A Current List with Definitions and Notes on Usage (pp 209-214). Classification of Chronic Pain, Second Edition, IASP Task Force on Taxonomy, edited by H. Merskey and N. Bogduk, ISAP Press, Seattle, 1994.
4 Cleveland Clinic. Acute vs. Chronic Pain. Available at: Accessed 8 September 2015.
5 International Association for the Study of Pain. Unrelieved pain is a major healthcare problem. Available at: Accessed 8 September 2015.