Acute Pain:
Very effective.

Chronic Pain:
Often ineffective. 5 out of 6 patients with persistent pain take regular pain killers, but an estimated 70% continue to feel severe pain.

Pain killers include simple analgesia such as paracetamol, non-steroidal anti-inflammatory medications (aspirin, ibuprofen and diclofenac) and stronger opiate based compounds such as codeine and morphine.