Pain is classified into physical and psychological pain. Physical pain is nociceptive, inflammatory, or neuropathic. Pain can be categorized into acute or chronic pain depending on the duration of pain and mechanism of onset. Acute pain heals as the underlying cause is resolved and includes naturally curable nociceptive and potentially curable neuropathic pain. Chronic pain is caused by incurable conditions or requires a long time to heal and is persistent: it includes chronic nociceptive pain, established neuropathic pain, and psychogenic pain. The therapeutic strategies for pain depend on the underlying pathological conditions: (1) For nociceptive pain, analgesics, narcotic analgesics, and nerve block are indicated. (2) For neuropathic pain, supplementary analgesics, but not analgesics, are indicated, and some narcotic analgesics are also effective: the recommended supplementary analgesics include calcium channel alpha-2-delta ligands, tricyclic antidepressants (TCAs), and serotonin-noradrenaline reuptake inhibitors (SNRIs). (3) For psychogenic pain, analgesics and nerve block are not indicated, except in the setting of a placebo effect: in paticular, narcotic analgesics should not be used. Psychological therapy, tranquilizer administration, cognitive behavior therapy, and patient education are indicated for this kind of pain.