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.