The Facts

Everyone has experienced pain at some time or other. A cut, a sports injury, childbirth, surgery, or kidney stones all can produce varying degrees of pain. In these cases, the pain has a known cause and resolves when the cause is no longer there. This type of pain is acute pain. Acute pain performs a function – it warns the body of a problem or injury.

Chronic pain, which is pain lasting months or recurring over years, is much different. The pain itself rarely continues to perform any useful function. Chronic pain can be quite disabling, often preventing people from working and enjoying life. It can lead to people feeling isolated, angry, frustrated, and guilty.


Many medical conditions or injuries can cause chronic pain. Some people will continue to experience pain long after recovering from an initial injury, such as a back injury. Other chronic pain is caused by chronic diseases such as arthritis or cancer, or by a lesion that does not heal. Some people have pain that does not have an identifiable cause. This is not to say that the pain is not real. Whatever the cause, chronic pain is real and should be treated.

The following conditions may be associated with chronic pain:

  • cancer
  • fibromyalgia
  • spinal injury
  • headaches
  • back injury
  • arthritis
  • nerve inflammation or damage

Sometimes pain can be felt in a part of the body that is no longer there. This is called phantom limb pain, which develops as a result of amputation. When pain in one part of the body is felt in another part of the body, it is called referred pain.

The internal organs are not very responsive to pain; instead, pain in these areas may be felt more as a diffuse pain (i.e., pain spread over a large area), which is not easy to localize.

Acute pain results when a disease or injury sends a signal to special sensory nerve endings called nociceptors. Nociceptors are located in the skin, as well as in other structures including blood vessels and tendons. Pain signals travel from the nociceptors, through the sensory nerves, and up the spinal cord to the thalamus in the brain. The signal is then sent to the cerebral cortex, the part of the brain that processes thought.

On the way to the brain, natural body chemicals can change the pain signal. Substance P makes the pain signal stronger. Endorphins make it weaker. Pain is not actually felt until the message or signals get to the brain. Chronic pain can originate at many points in the above pathway.

In some cases, chronic pain may arise from injury to the nerves in our body. This type of pain is called neuropathic pain and is often the result of direct injury or disease of the nerves. Neuropathic pain is different from acute, nociceptive pain – people often complain of burning or radiating pain rather than dull, aching pain.

The cerebral cortex and the limbic system, which are the brain areas controlling emotion, process pain signals. How much pain is felt depends on a number of factors. Factors that increase how badly pain is felt include the following:

  • previous bad experiences with pain
  • insomnia
  • anxiety
  • depression

Anxiety can make pain much worse. Not knowing the cause of pain makes people anxious. The pain often seems less severe once they have a diagnosis of their medical condition. Worry about the seriousness of their condition can often also increase the severity of the pain.

Symptoms and Complications

Living with chronic pain can create a vicious cycle of anxiety, dependence on other people, and sleep deprivation. Chronic pain can make it unpleasant for people to live their daily life normally; it saps their energy and often negatively affects employment.

People suffering from chronic pain might stop social activities because of the pain. They might feel dependent on other people to help with daily tasks such as shopping. Sleeping can be difficult for someone who is in pain, or worried about being in pain. Constant pain and/or sleep deprivation can lead to depression or worsen existing mood disorders. Chronic pain may also cause a decrease in libido and appetite, as well as weight loss.

Making the Diagnosis

Pain that lasts 3 months or longer, or pain persisting over 1 month after an injury resolves is considered chronic pain.

Although it can be hard to describe pain exactly, your doctor needs to know how it feels and where it's coming from, what aggravates the pain, how it impacts your daily life, and what makes it better. Doctors often use pain scales to help rate the intensity of the pain and imaging tests to find out more about its possible causes.

Treatment and Prevention

Treatment for chronic pain blocks the pain signal anywhere in the pathway from the skin to the spinal cord nerves and from the spinal cord to the thalamus and cortex. Treatment ranges from traditional medications to complementary therapies.

Painkillers, also called analgesic medications, are often used to lessen chronic pain. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and naproxen can provide some relief.

Acetaminophen is also commonly used. These medications are usually tried first. If they are ineffective, stronger medications such as opioids might be added.

Opioids (also referred to as narcotics) such as morphine and codeine reduce certain types of pain. Opioids have caused concerns because they have been linked to dependence and addiction. They are strong analgesics and have significant potential to become habit-forming, and they can cause drowsiness, nausea, constipation, dizziness, and itching.

Although many people are afraid of becoming addicted to opioids, addiction is uncommon when the medication is used appropriately. Addiction involves a psychological need to abuse drugs that is different from tolerance (needing higher doses of medication to keep the same level of pain control) and dependence (experiencing withdrawal symptoms if the medication is stopped suddenly).
Other medications such as corticosteroids reduce the pain of bone cancer and anticonvulsant medications relieve the pain of damaged nerves. Some types of antidepressants are also helpful for nerve-related pain.

A number of complementary therapies are used in addition to medications in the management of chronic pain, including an individualized physical therapy program. Stretching and exercises to improve range of motion can allow for gradual improvements in physical functioning. An exercise program should be tailored specifically to a person’s needs and limitations.

Transcutaneous electrical nerve stimulation (TENS) directs electrical energy through the skin using electrodes. Though it is not know exactly how TENS helps with pain, it is thought that the energy starts a natural reaction in the spinal cord that relieves the pain. Not all people respond to TENS, but it does provide some pain relief for certain individuals.

If someone suffers from chronic pain that's carried by one or more specific nerves, they can have a nerve block, which temporarily or permanently stops the pain signal from traveling along that particular nerve. An injected anesthetic blocks the nerve from carrying the pain signals. People can also have the nerves destroyed by surgery or by hot or cold treatments. The pain can return, however, and some people may lose feeling or movement in the part of the body controlled by the destroyed nerve.
In extreme cases, implantable nerve stimulators can be placed in the spinal cord to change the sensation from pain to parasthesia (tingling).

Acupuncture is used to treat many painful conditions, including migraine and back pain. In acupuncture, the acupuncturist will insert thin needles just under the skin at specific points on the body. Acupuncture probably stimulates natural anti-pain chemicals in the spinal cord. Relaxation and meditation techniques can help relax muscles, relieve anxiety, and help reduce pain.

Biofeedback may relieve chronic pain. In biofeedback, an instrument measures breathing, heart rate, and other specific bodily responses and feeds them back in the form of light or sound. People can then learn to control these bodily responses through relaxation and cognitive techniques.

Various forms of psychological treatments have been used to help relieve chronic pain. Cognitive therapy can help people substitute positive thoughts for negative ones. Behaviour therapy tries to change the activity level of people with chronic pain.

*All medications have both common (generic) and brand names. The brand name is what a specific manufacturer calls the product (e.g., Tylenol®). The common name is the medical name for the medication (e.g., acetaminophen). A medication may have many brand names, but only one common name. This article lists medications by their common names. For information on a given medication, check our Drug Information database. For more information on brand names, speak with your doctor or pharmacist.

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