Some GP's never prescribe opiates for chronic pain conditions and diseases, and yet others are quite happy to give you them.
If your pain is not relieved with analgesics like NSAIDS (Non steroidal anti-inflammatory drugs) Tricyclics (anti-depressants), or Paracetamol then opiates such as Morphine, Codeine, Hydrocodone, or Oxycodone, may be used.
They say that some GP's may even ask you to sign a 'contract' for opiate drugs, outlining the appropriate use of the drugs and possible side effects, to confirm that you understand completely what is involved.
The big debate between the two types of pain relievers is the possible 'addiction' factor with opiates. However although these drugs carry a heightened risk of addiction, research has apparantly shown that providers concerns that patients will become addicted to them is largely unfounded, especially when being used for chronic pain.