Chronic Pain involves multiple pathophysiological mechanisms with peripheral and central components. Multiple levels of the nervous system with multiple neurotransmitters are involved in pain transmission. Therefore, it is not easy to plan effective pharmacological therapy for chronic pain and pain treatment often involves the use of one or a combination of agents with analgesic action.  

Chronic Pain can be nociceptive or neuropathic. Nociceptive pain usually is treated with anti-inflammatory or analgesic medications. Neuropathic pain typically is treated with medications that influence neurotransmitters (e.g. antidepressants, antiepileptic drugs), and treatment with opioids is reserved for patients with refractory neuropathic pain. Unfortunately, there is no truly effective medicines for certain types of pain.