Opioids are powerful painkilling drugs that are usually prescribed to treat acute pain or cancer pain. In some cases, these morphine-like medications may be used to treat chronic pain that is not related to cancer, such as severe joint pain or pain related to nerve damage.

Opioids include natural opiates (derived from the opium poppy plant) and synthetic narcotics. Exactly how they relieve pain is unclear, but they appear to:

• Block pain messages to the brain
• Change the brain’s interpretation of pain

Although opioids are effective in providing pain relief, many physicians do not prescribe them because they fear their patients may become addicted and because of stringent regulations by the U.S. Drug Enforcement Agency.

Opioids are powerful medications often used to manage pain. Sometimes referred to as narcotics, these drugs include natural opiates (derived from the opium poppy plant) and synthetic narcotics. Centuries after they were first used by physicians, opiates remain among the most effective analgesics available. They are often used to relieve pain associated with cancer, terminal illness, severe injury or surgery.

The sensation of pain occurs when trauma to the body (caused by illness or injury) activates specialized nerves, which carry pain messages to the spinal cord. The messages are then relayed to neurons, which carry them to the brain.

Opioids relieve pain by attaching to specific proteins called opioid receptors that are found in the brain, spinal cord and gastrointestinal (GI) tract. They work in two ways:

• Blocking pain messages to the brain. In the spinal cord, opioids disrupt the transmission of pain messages between neurons. This keeps the pain signals from reaching the brain.
  
  
• Changing the brain’s interpretation of pain. In the brain, opioids work by acting on brain regions involved in interpreting pain messages. Rather than blocking pain messages, they change how a person experiences feelings of pain.

However, exactly how opioids exert their anti-pain effects remains unclear.

Opioids are available only by prescription, but many physicians do not prescribe them for chronic pain conditions because they fear their patients may become addicted.

New research by the Centers for Disease Control and Prevention (CDC) found that, as the number of opioid prescriptions has risen in recent years, so have fatal overdoses. Between 1999 and 2002, prescription opioids caused more overdose deaths than cocaine or heroin, the CDC reported in 2006. Still, the agency cautioned that the findings should not cause physicians or patients to have unwarranted fear about using opioids to control pain.

Opioids are available as tablets, capsules, lozenges, syrups, patches, suppositories and injections.

Opioids are sometimes referred to as narcotics. They include morphine and other natural and synthetic chemicals that are similar to morphine in structure. Opioids include:

• Natural opioids
  
  
• • Morphine. Often used before or after surgery to block severe pain. Sometimes referred to as the “gold standard” among opioids, it is the drug against which all others in this class are compared.  However, it is not more effective than other opioids.
    
    
  • Codeine. Usually used to treat pain that is milder than pain treated with morphine.
    
    
• Semisynthetic opioids
  
  
• • Oxycodone. Commonly used alone or in combination with aspirin or acetaminophen.
    
    
  • Hydromorphone. Derived from morphine in the 1920s. It is as effective as morphine and is often better tolerated.
    
    
• Synthetic opioids
  
  
• • Fentanyl. Produces faster onset and shorter duration of pain relief than morphine when its given by injection, but not when given in transdermal or orally disolving forms.
    
    
  • Meperidine. Used less often than some other opioids because it is associated with a higher incidence of side effects. Because of this, its use is generally contraindicated for any type of pain.
    
    
  • Propoxyphene. A relatively weak opioid that provides much less pain relief than other opioids. Therefore its use is not generally recommended.

Other prescribed opioids include hydrocodone, levorphanol, methadone and oxymorphone. There is also an analgesic called tramadol that contains a weak opioid.

Opioids are usually prescribed to manage conditions and procedures such as:

• Cancer pain
• Terminal illness
• Severe injury and trauma pain
• Severe musculoskeletal pain, such as back pain, neck pain or other joint pain
• Surgical and postsurgical pain
• Postpartum (after-labor) pain
• Sickle cell anemia crises
• Severe dental pain
• Painful diabetic neuropathy
• Migraines or other headaches

Though other medications such as acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs) are often used with arthritis, recent research indicates that controlled-release opioids can ease pain in people with moderate to severe osteoarthritis.

Opioids are sometimes used to treat severe diarrhea or severe coughing. Opioids are also used to block pain during numerous medical and dental procedures and may be used just before or during an operation to help anesthesia work more effectively.

Patients who have certain conditions should inform their physician of the fact before using opioids. Such conditions include:

• Alcohol or drug addiction
• Emotional problems
• Brain disease or head injury
• Emphysema, asthma or other chronic lung diseases
• Enlarged prostate (benign prostatic hyperplasia) or problems with urination
• Gallbladder disease or gallstones
• Colitis
• Heart disease
• Kidney disease
• Liver disease
• Underactive thyroid (hypothyroidism)
• History of seizures

Opioids may affect the part of the brain that mediates feelings of pleasure. As a result, people who take these medications often experience feelings of euphoria that can lead to addiction in some users. Patients with a history of psychological problems or substance abuse have a greater risk for opioid addiction.

Opioid medications rarely cause addiction when used correctly under a physician’s close supervision for acute pain and cancer pain. However, there is a risk of addiction, which is also called psychological dependence, when opioids are used to treat chronic pain, even in patients with no history of drug abuse. 

People who use opioids over an extended period may develop two conditions that are often confused with addiction: tolerance and physical dependence. Neither of these is a form of addiction.

Chronic use of opioids may result in the user developing a tolerance to the drug. When this occurs, increasingly higher amounts of the opioid are required before the user obtains the same initial effect.

Physical dependence may occur in patients who use opioids for more than a few weeks. When a person’s body becomes dependent upon an opioid, the body requires the substance to avoid going into withdrawal. To avoid withdrawal, patients need to gradually taper off using opioids rather than quitting them “cold turkey.” Symptoms of withdrawal associated with opioids include:

• Restlessness
• Muscle pain and bone pain
• Insomnia
• Diarrhea
• Vomiting
• Cold flashes (including associated “goose bumps”)
• Involuntary leg movements

Use of opioids also may cause patients to experience other side effects. Some of the more common side effects include:

• Drowsiness
• Constipation
• Itching
• Mild dizziness, lightheadedness or fainting
• Unclear thinking
• Nausea and vomiting
• Dry mouth
• Sedation
• Decreased levels of the hormone testosterone, causing reduced sex drive
• Cardiovascular effects, such as accelerated heart rate
• Depression of respiration and cough reflex
• Gastrointestinal disorders
• Decreased motor response rate
• Urinary retention

In addition, opioids slow activity in the respiratory center of the brainstem. If taken in high doses, opioids can cause severe respiratory distress and may even result in death. If opioids are used for an extended periods they can actually increase pain. This condition is known as hyperalgesia. The mechanism that causes this is unclear. The current thinking is that it may be due to the effects of opioids on chemical receptors in the brain.

Patients should seek immediate medical care if they experience any of the following more serious side effects related to opioids:

• Extreme restlessness or nervousness
• Confusion
• Dizziness
• Severe weakness
• Extreme drowsiness
• Cold, clammy skin
• Breathing difficulties
• Low blood pressure
• Slow heartbeat
• Convulsions
• Constricted pupils (miosis)

Patients should consult their physician before taking any additional prescriptions, over–the–counter medications, nutritional supplements or herbal medications. Of particular concern are drugs and substances that can severely reduce respiration when combined with opioids. These substances include:

• Alcohol
• Antihistamines
• Barbiturates
• Benzodiazepines

Opioids can be used safely to ease acute pain and cancer pain in children. These drugs are frequently prescribed for pain relief in pediatric patients, though only some have been specifically approved by the U.S. Food and Drug Administration (FDA) for this purpose. The FDA notes that common pediatric uses of opioids include acute trauma or illness, burns, surgery and procedures, mechanical ventilation, cancer pain and sickle cell anemia crises.

There is limited research on the use of opioids for the treatment of chronic pain in children, and the effects of extended continuous opioid use on them are unclear.

One recent research project found that an opioid delivered through a skin patch helped children with cancer and other severe pain, with no more adverse affects than reported in adults.

Dosage adjustments may be necessary when prescribing opioids for children to prevent symptoms such as unusual excitement and restlessness. Newborns are more sensitive to the depressant effects of opioids such as morphine, and it may take longer for infants to clear opioids from their bodies. In addition, children under age 2 who use opioids may be prone to breathing problems.

People should never give opioids to children unless under supervision and guidance of a pediatrician.

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about opioids:

1. Are opioids the best choice to relieve my pain? Why?
   
   
2. What are my alternatives?
   
   
3. How do opioids work to relieve my pain?
   
   
4. What are my risks when using opioids?
   
   
5. What is the name and dosage of the opioid I am being prescribed? How and when should I take it?
   
   
6. Can this drug interact with my other medications?
   
   
7. What should I do if I miss a dose or take too much?
   
   
8. At what point should I report side effects to you?
   
   
9. Can I drink any alcohol when using this opioid?
   
   
10. I’ve heard that opioids are highly addictive. Is this true?
    
    
11. Will my body become dependent upon opioids?
    
    
12. Is it OK if I drive or operate machinery while using opioids?