Pain is the symptom that most often opens the clinic door
Pain is a distressing feeling tied to actual or potential tissue harm—an IASP definition that includes sensory and emotional halves. It pushes animals to withdraw, guard, and learn avoidance. In wealthy countries it is the top reason people see physicians, reshaping memory, mood, and work.
The International Association for the Study of Pain describes pain as an unpleasant experience, both sensory and emotional, linked to real or potential tissue damage or resembling it. Its evolutionary job is protective: pull away from harm, shield an injured part while it mends, and learn to avoid a repeat. Usually it fades once the cause is gone and healing is done, but it can outlast both, and it sometimes appears with no detectable injury or disease at all.
Clinicians sort pain into three broad kinds. Nociceptive pain comes from inflamed or damaged tissue triggering pain sensors called nociceptors, and is split into superficial and deep types. Neuropathic pain comes from damage or malfunction in the nervous system itself, and patients often call it burning, tingling, electric or stabbing. Nociplastic pain arises without clear evidence of tissue or nerve damage. Pain that clears quickly is acute; the association labels pain chronic when it persists or recurs beyond 3 months, as can happen with rheumatoid arthritis or cancer.
Some forms are strange. In allodynia, a normally harmless touch, pressure or temperature hurts. Phantom pain is felt in an amputated limb and counts as neuropathic. It affects close to 82 percent of upper-limb amputees and 54 percent of lower-limb amputees; one study found 72 percent had it eight days after surgery and 67 percent six months later.
Pain is the leading reason people consult a doctor in most developed countries. It erodes concentration, working memory, mental flexibility and processing speed, and raises the odds of irritability, depression and anxiety. Simple over-the-counter painkillers help in 20 to 70 percent of common acute cases, such as the ache after a tooth extraction, while social support, cognitive behavioural therapy, excitement or distraction can change how intense or unpleasant it feels. The English word, first recorded as peyn in 1297, descends via French and Latin from a Greek term for a penalty or price paid.
Source: Pain
