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What is pain?

Pain is a sensation triggered by the nervous system in response to tissue damage or other damage to the body. Pain can be a dull, achy, stabbing, shooting, burning, or a pins-and-needles sensation. You may feel pain in a specific area of the body, such as your back, or you may feel aches and pains all over, such as when you have the flu (influenza).

The experience of pain is invariably tied to emotional, psychological, and cognitive factors.

Pain can be due to a wide variety of diseases, disorders and conditions that range from a mild injury to a debilitating disease. Pain can be categorized as acute, chronic, referred, cancer, neuropathic, and visceral.

Acute pain is experienced rapidly in response to disease or injury. Acute pain serves to alert the body that something is wrong and that action should be taken, such as pulling your arm away from a flame. Acute pain often resolves within a short time once the underlying condition is treated.

Chronic pain is defined as lasting more than three months. Chronic pain often begins as acute pain that lingers beyond the natural course of healing or after steps have been taken to address the cause of pain.

Referred pain is pain that originates in one part of the body but is felt in another part of the body.

Cancer pain is due to malignancy.

Neuropathic pain is caused by damage to the nervous system and is often perceived as tingling, burning, and pins-and-needles sensations called paresthesias.

Visceral pain is caused by a problem with the internal organs, such as the liver, gallbladder, kidney, heart or lungs.

Recent studies have found that some people with chronic pain may have low levels of endorphins in their spinal fluid. Endorphins are neurochemicals, similar to opiate drugs (like morphine), that are produced in the brain and released into the body in response to pain. Endorphins act as natural pain killers. Chronic pain most often affects older adults, but it can occur at any age. Chronic pain can persist for several months to years.

Pain can be a sign of a serious disease or condition. If you are experiencing severe pain, chest pain, difficulty breathing, bleeding symptoms, or a change in consciousness, seek immediate medical care (call 911). If your pain is persistent, or causes you concern, talk with your medical professional about your symptoms. Research into the diagnosis and treatment of chronic pain is ongoing, so ask your health care professional for the latest information.


What other symptoms might occur with pain?

Pain may occur with other symptoms depending on the underlying disease, disorder or condition. For instance, if your pain is due to arthritis, you may experience pain in more than one joint. Pain due to a compressed nerve in the lower back can even lead to loss of bladder control. Pain is often a major symptom of fibromyalgia, which is also characterized by fatigue and sleep problems.

Symptoms that might occur along with pain

The range of symptoms that may occur with pain include:

Serious symptoms that might indicate a life-threatening condition

In some cases, pain may occur with other symptoms that might indicate a serious or life-threatening condition, such as a heart attack. Seek immediate medical care (call 911) if you, or someone you are with, have any of these serious symptoms, with or without pain, including:


What causes pain?

Hundreds of diseases, disorders and conditions can cause pain, such as inflammatory syndromes, malignancy, trauma, and infection. In some cases, pain may be a symptom of a serious or life-threatening condition, such as a heart attack or cancer.

Traumatic causes of pain

Pain can be due to any kind of injury or trauma including:

  • Amputation (removal of a body part)
  • Avulsion (forcible tearing away of a body part
  • Blunt force trauma
  • Broken bone
  • Burn
  • Electrical injury
  • Eye injury, such as corneal abrasion
  • Foreign body
  • Laceration or contusion
  • Sports or orthopedic injury, such as a torn meniscus or dislocated joint
  • Sprains and strains
  • Surgery

Degenerative and inflammatory causes of pain

Pain can be due to degenerative and inflammatory disorders, such as:

Causes of neuropathic pain

Pain can be caused by peripheral or central nervous system damage or injury from the following conditions:

Other possible causes of pain

Pain can be caused by a variety of other diseases, disorders and conditions including:

What are the potential complications of pain?

Complications associated with pain depend on the underlying disease, disorder or condition. For example, pain resulting from a degenerative condition such as multiple sclerosis can lead to inactivity and its associated complications. Fortunately, pain can often be alleviated or minimized by physical therapy, basic self-help measures, and following the treatment plan outlined by your doctor.

However, in some cases the degree and duration of your pain may become overwhelming and affect your everyday living. Research into the diagnosis and treatment of chronic pain is ongoing, so contact your health care professional for the latest information.

Over time, pain can lead to complications including:

  • Absenteeism from work or school
  • Dependence on prescription pain medication
  • Pain that does not respond to treatment (intractable pain)
  • Permanent nerve damage (due to a pinched nerve) including paralysis
  • Physiological and psychological response to chronic pain
  • Poor quality of life
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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2018 Dec 20
  1. Pain: Hope Through Research. National Institute of Neurological Disorders and Stroke.
  2. Textbook of Basic Nursing, Edition 9, Rosdahl and Kowalski, 2008.
  3. Pizzo PA, Clark NM. Alleviating suffering 101--pain relief in the United States. N Engl J Med 2012; 366:197
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