Table 1.

Different types of pain

Type	Pathophysiology	Characteristics	Examples
Based on underlying pathophysiology
Nociceptive pain	Activation of nociceptors in response to noxious stimuli	Sharp, burning pain (somatic) or dull, aching pain (visceral)	Back pain, headaches, neck pain, shoulder pain, pain due to burns and injuries
Neuropathic pain	Central sensitization or neuronal damage	Severe, burning, shooting or numbing pain, increased sensitivity to stimuli (hyperalgesia and allodynia)	Peripheral neuropathy, diabetic neuropathy, trigeminal neuralgia, complex regional pain syndrome (CRPS), neuropathic pain due to spinal injury
Mixed pain	Nociceptive and neuropathic origin	Severe, shooting pain or dull, aching pain or pain with mixed characteristics	LBP with radiculopathy, cancer pain
Based on duration
Acute pain	Activation of peripheral nociceptors, accompanied by release of COX enzymes and prostaglandins	Lasts from few seconds to less than 6 months	Injuries, headaches, sprains, postoperative pain, back pain
Chronic pain	Sensitization at the level of spinal neurons via multiple mechanisms	Lasts for ≥6 months	Chronic primary pain, cancer pain, posttraumatic and postsurgical pain, neuropathic pain, headache and orofacial pain, visceral pain, musculoskeletal pain
Breakthrough pain	Pain in a well-treated patient due to movement (incidental), spontaneous or resulting from weaning off of drugs or effect of drug	Lasts from few seconds to hours	Cancer pain
Based on etiology
Cancer pain	Caused due to cancer itself (brain tumors, breast cancer), drug treatment (chemotherapy, radiation) or associated disease (neuropathy)	Acute or chronic pain of mild, moderate or severe intensity with/without breakthrough pain	All types of cancers
CNCP	May have multiple etiologies	Moderate-to-severe pain with/without restricted mobility	Rheumatoid arthritis, osteoarthritis
Based on location
LBP	Caused due to bad posture, strains/sprains, underlying disease (malignancy or infection) or referred pain (kidney or gall stones)	Mild and moderate-to-severe pain with/without impaired movement or physical function	Acute LBP, herniated disk, spondylosis
Neck pain and shoulder pain	Caused due to strains, sprains, incorrect posture and compression of spinal cord or injuries	Mild and moderate-to-severe pain with/without impaired movement or physical function	Axial neck pain, cervical radiculopathy
Headaches	Caused due to incorrect posture, stress, migraine or underlying disease (tumors)	Headache associated with migraine may present additional symptoms (aura), visual problems or vertigo	Tension-type headaches, migraine headaches
Referred pain	Type of visceral pain that radiates to surrounding regions	May be sharp, pulsating pain or dull, aching pain depending upon the origin	Angina (jaws and shoulders), stones (abdomen and back)

Abbreviations: CNCP, chronic noncancer pain; COX, cyclooxygenase; LBP, low-back pain.