Cleveland Clinic

Acute vs. Chronic Pain

What is pain?

Pain is an uncomfortable feeling and/or an unpleasant sensation in the body. The presence of pain often is an indication that something is wrong. Pain can appear suddenly or can come about slowly.

Each individual is the best judge of his or her own pain. Feelings of pain can range from mild and occasional to severe and constant. Pain can be classified as acute pain or chronic pain.

What is acute pain?

Acute pain begins suddenly and is usually sharp in quality. It serves as a warning of disease or a threat to the body. Acute pain might be caused by many events or circumstances, including:

  • Surgery
  • Broken bones
  • Dental work
  • Burns or cuts
  • Labor and childbirth

Acute pain might be mild and last just a moment, or it might be severe and last for weeks or months. In most cases, acute pain does not last longer than six months, and it disappears when the underlying cause of pain has been treated or has healed. Unrelieved acute pain, however, might lead to chronic pain.

What is chronic pain?

Chronic pain persists despite the fact that the injury has healed. Pain signals remain active in the nervous system for weeks, months, or years. Physical effects include tense muscles, limited mobility, a lack of energy, and changes in appetite. Emotional effects include depression, anger, anxiety, and fear of re-injury. Such a fear might hinder a person's ability to return to normal work or leisure activities. Common chronic pain complaints include:

  • Headache
  • Low back pain
  • Cancer pain
  • Arthritis pain
  • Neurogenic pain (pain resulting from damage to nerves)
  • Psychogenic pain (pain not due to past disease or injury or any visible sign of damage inside)

Chronic pain might have originated with an initial trauma/injury or infection, or there might be an ongoing cause of pain. However, some people suffer chronic pain in the absence of any past injury or evidence of body damage.

What is the difference between acute and chronic pain?

There might be no known cure for the disease (such as arthritis or phantom pain) that is causing the chronic pain.
The cause of chronic pain might be unknown or poorly understood.

How is pain treated?

Depending upon its severity, pain might be treated in a number of ways. Symptomatic options for the treatment of pain might include one or more of the following:

  • Non-steroidal anti-inflammatory drugs (NSAIDs), a specific type of painkiller such as Motrin® or Aleve®
  • Acetaminophen (such as Tylenol®)
  • Narcotics (such as morphine or codeine)
  • Localized anesthetic (a shot of a pain killer medicine into the area of the pain)
  • Nerve blocks (the blocking of a group of nerves with local anesthetics)
  • Acupuncture
  • Electrical stimulation
  • Physical therapy
  • Surgery
  • Psychotherapy (talk therapy)
  • Relaxation techniques such as deep breathing
  • Biofeedback (treatment technique in which people are trained to improve their health by using signals from their own bodies)
  • Behavior modification

Some pain medicines are more effective in fighting pain when they are combined with other methods of treatment. Patients might need to try various methods to maintain maximum pain relief.

What causes chronic pain?

There are many possible causes of chronic pain. According to the Institute for Clinical Systems Improvement, chronic pain can be grouped into four main types.

  • Neuropathic (nerve-related) pain—This is pain caused by damage to or malfunctioning of the somatosensory system. This is the system made up of sensory receptors and neurons (nerve cells) in the central nervous system and the peripheral nervous system (outside of the central nervous system). One example of neuropathic pain is sciatica (pain in the back, hip, and upper thigh related to the sciatic nerve).
  • Muscle pain—Problems with the skeleton’s muscles are a frequent cause of chronic pain. Myofascial pain (muscle tissue pain) can affect areas such as the lower back, hips, legs and feet, neck, shoulders, arms, and trunk of the body. It often occurs after an injury or following repetitive motions.
  • Inflammatory pain—Inflammatory agents trigger main sensory nerves that send pain signals to the spinal cord. Causes include arthritis, tissue injury, or infection. It may also be due to conditions that occur after surgery. Symptoms may include redness, warmth, and swelling at the site of the pain.
  • Mechanical/compressive pain—Mechanical pressure or stretching activates nerve cells that are sensitive to pain. Causes may include fractures, disc degeneration, or compression of tissue by tumors, cysts, or bony structures.

A person may have multiple conditions that cause chronic pain (for example, cancer and osteoarthritis).

In some cases, people have chronic pain when there is no apparent underlying cause that can be found. This is known as psychogenic pain. Psychogenic pain does not mean that a person is “making it up” or “crazy.” The pain is very real. However, psychological factors such as anxiety, depression, excessive stress, or environmental factors are the major explanations for this type of chronic pain.

Other types of chronic pain with no apparent cause may result from changes in the central nervous system. Sometimes after a disease or injury occurs, the central and peripheral nervous systems undergo abnormal changes in their structure and function. These changes may make people extra-sensitive to pain and may produce sensations of pain well after the injuries are healed. These dysfunctional changes in the central nervous system are known as central sensitization. Once the central nervous system has become hypersensitive to pain, it is difficult to reverse the hyperactivity and the associated persistent pain.

What is chronic pain? What is the difference between chronic and acute pain?