Pain is a signal from the body that something is wrong.

Sarah's Story

Sarah woke up Monday morning with pain in her throat. She did not mention it to her mother before heading for school, and the pain continued to worsen during the day. By evening Sarah could barely swallow, and when her mother looked into her mouth, she saw that Sarah's tonsils were red and inflamed.

The pain did not go away, and on Thursday morning, her mother took Sarah to the doctor. After taking a history and examining Sarah's throat, the doctor used a swab to collect a culture * . The culture indicated that Sarah had strep throat (a contagious infection caused by bacteria called Group A beta-hemolytic Streptococcus pyogenes), and the doctor prescribed a course of antibiotics as treatment. After a few days on the antibiotics, the pain went away, and after 10 days, Sarah's strep throat was healed.

Without the pain that accompanied her sore throat, Sarah and her mother might not have realized that Sarah had an infection that, if left untreated, could have made her seriously ill.

What Is Pain?

Pain is one of the body's signals that something is wrong. In Sarah's case, the pain of a sore throat was the harbinger of a strep infection. Pain is an unpleasant, uncomfortable feeling conducted from the site of an injury by the nervous system * to the brain. Pain serves several functions: as a warning of an injury; as a means of preventing further injury; and as a cause of reduced activity to allow healing to proceed.

In the brain, the pain messages first enter the thalamus, a part of the brain that diverts nerve impulses to the proper areas of the brain. Pain signals are routed to three areas of the brain: the frontal cortex, the thinking and reasoning part of the brain; the somatosensory cortex, the part of the brain that handles physical sensations; and the limbic system, the part of the brain that controls the emotions.

The body releases natural chemicals that can intensify the perception of pain, such as prostaglandins, compounds that have many functions in the body, including to sensitize the nerve cells in the spinal cord to pain. The analgesic (pain-killing) aspirin blocks the receptors on the cells that are keyed to receive prostaglandins and thus interfere with its effect, relieving pain. Endorphin, another neurotransmitter *

Medical professionals use pain intensity scales to help determine the level of pain a person is suffering.

Medical professionals use pain intensity scales to help determine the level of pain a person is suffering.
Public Domain.

Each person experiences pain in a unique way. How pain is interpreted and handled is affected by a variety of factors, such as age, gender, emotional state, previous experiences of pain, and attitude. Upbringing and social or cultural background can also affect a person's experience of pain, such as the famous British “stiff upper lip” expectation that a person would not show a reaction to pain.

What Are the Two Main Types of Pain?

The human body can experience acute pain, which strikes quickly and leaves quickly (usually within six weeks), such as after a fall, or chronic pain, which can also strike quickly but lingers, sometimes for years.

An example of acute pain is the pain of a sprained ankle. After the stretching of the ankle's ligaments, the pain receptors in the area signal the brain. The brain responds by not putting weight on the injured joint so as not to cause additional damage.

Acute pain can often be successfully treated with over-the-counter pain medications called analgesics. Some analgesics not only relieve pain but also reduce inflammation.

However, intense pain can be the sign of a life-threatening condition. A feeling of pressure, fullness, squeezing, or pain in the center of the chest or pain that is radiating down one or both arms or into the jaw may signal a myocardial infarction (heart attack). Someone experiencing such symptoms should seek medical help immediately.

A doctor will ask the patient to describe the location of the pain and indicate its severity, perhaps by using a scale from 0 to 10 (0 being no pain, 10 being worst), words (such as no pain, mild, moderate, and severe), or faces that by their expressions show the extent of the pain. The doctor may order tests or procedures, such as x-rays, MRIs * , or laboratory tests, to determine if the pain is the result of an injury, such as fractured bone, or an infection or a heart attack. Once the underlying cause is treated, pain usually disappears.

Chronic pain may come and go or be a constant lingering ache, but it occurs over a period of six months or more. For people who suffer from migraine headache, the pain comes on suddenly and can be incapacitating. On the other hand, people with fibromyalgia * experience a constant pain throughout the body. More than 100 million Americans live with chronic pain, and 58 percent of chronic-pain sufferers report experiencing anxiety or depression. Chronic pain affects people's quality of life.

The most common types of chronic pain are lower back pain, migraine headaches, neck pain, and facial pain. Arthritis * , fibromyalgia, and cancer all cause chronic pain, as can diabetes * and shingles (a painful contagious rash). Chronic pain can result from an initial injury, such as a back injury suffered during a car accident, but for an unknown reason the central nervous system continues to send pain messages after the injury heals.

How Is Pain Treated?

Pain can be relieved by medications called analgesics. There are two main groups of analgesics that are available without prescription: nonsteroidal anti-inflammatory drugs (NSAIDs) and acetaminophen * . Although they are available over the counter (OTC), both groups must be taken with caution; excessive doses of acetaminophen can cause liver damage, and NSAIDs can damage the stomach.

Stronger pain relievers, such as narcotics, are available only with a prescription because they can cause physical and psychological dependence. They may be administered by mouth or intravenously.

The pain of childbirth is acute but can be relieved in a number of ways. A woman in labor may opt for an epidural or a spinal block, in which a local anesthetic is injected into the lower part of the body to block pain signals. A woman may control pain with behavioral techniques such as relaxation exercises and controlled, rhythmic breathing.

Like acute pain, chronic pain can be treated with pain relievers. In some cases, such as fibromyalgia, antidepressant medications * can be helpful. Exercise and alternative therapies such as acupuncture (a technique to relieve pain by inserting and manipulating fine needles in the skin) can also help to relieve chronic pain. Research continues to explore ways to relieve the suffering of people who experience chronic pain.

See also Appendicitis • Autoimmune Disorders: Overview • Broken Bones (Fractures) • Burns • Cancer: Overview • Carpal Tunnel Syndrome • Cerebral Palsy • Chronic Illness • Collagen Vascular Diseases: Overview • Crohn's Disease • Diverticulitis/Diverticulosis • Ear Infection (Otitis) • Ebola Virus Disease • Endometriosis • Fibromyalgia • Gastroenteritis • GERD (Gastroesophageal Reflux Disease) • Gout • Growing Pains • Guillain-Barré Syndrome • Headache • Hemorrhoids • Hernia, Gastrointestinal • Inflammatory Bowel Disease • Intestinal Infections • Intestinal Obstruction • Kidney Stones • Knee Injuries: Overview • Lou Gehrig's Disease (Amyotrophic Lateral Sclerosis) • Lupus • Multiple Sclerosis (MS) • Muscle Spasms and Cramps • Muscular Dystrophy • Parkinson's Disease • Pelvic Inflammatory Disease (PID) • Peptic Ulcer • Repetitive Stress Syndrome • Sciatica • Scleroderma • Shingles (Herpes Zoster) • Slipped (Herniated) Disk • Spina Bifida • Spinal Cord Injury • Sports Injuries: Overview • Temporomandibular Joint (TMJ) Syndrome • Tendinitis • Tennis Elbow (Epicondylitis) • Wounds


Books and Articles

ACPA Resource Guide to Chronic Pain Medication & Treatment, 2015 Edition. American Chronic Pain Association. (accessed August 24, 2015).

Foreman, Judy. A Nation in Pain: Healing Our Biggest Health Problem. New York: Oxford University Press, 2015.

Nelsen, Eleanor. “Teaching the Nervous System to Forget Chronic Pain.” NOVA Next. August 13, 2014. (accessed August 11, 2015).

Steiner, Brian. “Treating Chronic Pain with Meditation.” The Atlantic. April 1, 2014. (accessed August 11, 2015).


MedlinePlus. “Chronic Pain.” U.S. National Library of Medicine, National Institutes of Health. (accessed August 11, 2015). (accessed August 11, 2015).


American Academy of Family Physicians. PO Box 11210, Shawnee Mission, KS 66207-1210. Toll-free: 800-274-2237. Website: (accessed August 11, 2015).

American Chronic Pain Association. PO Box 850, Rocklin, CA 95677. Toll-free: 800-533-3231. Website: (accessed August 11, 2015).

International Association for the Study of Pain (IASP). 1510 H St. NW, Suite 600, Washington, DC 20005-1020. Telephone: 202-524-5300. Website: (accessed August 24, 2015).

* culture (KUL-chur) is a test in which a sample of fluid or tissue from the body is placed in a dish containing material that supports the growth of certain organisms. Typically, within days the organisms will grow and can be identified.

* nervous system is a network of specialized tissue made of nerve cells, or neurons, that processes messages to and from different parts of the human body.

* neurotransmitter (NUR-o-tranz-mit-er) is a chemical substance that transmits nerve impulses, or messages, throughout the brain and nervous system and is involved in the control of thought, movement, and other body functions.

* MRI, which is short for magnetic resonance imaging, produces computerized images of internal body tissues based on the magnetic properties of atoms within the body.

* fibromyalgia (fi-bro-my-AL-ja) is a group of disorders that are characterized by achy, tender, and stiff muscles.

* arthritis (ar-THRY-tis) refers to any of several disorders characterized by inflammation of the joints.

* diabetes (dye-uh-BEE-teez) is a condition in which the body's pancreas does not produce enough insulin or the body cannot use the insulin it makes effectively, resulting in increased levels of sugar in the blood. This can lead to increased urination, dehydration, weight loss, weakness, and a number of other symptoms and complications related to chemical imbalances within the body.

* acetaminophen (uh-see-te-MIHnoh-fen) is a medication commonly used to reduce fever and relieve pain.

* antidepressant medications are used for the treatment and prevention of depression.

Disclaimer:   This information is not a tool for self-diagnosis or a substitute for professional care.

(MLA 8th Edition)