Commonly Used Terms

  • Acute Pain – Pain that usually starts suddenly and has a known cause, like an injury or surgery. It normally gets better as your body heals and lasts less than three months.
  • Analgesics – Pain relieving medications including over-the-counter medications like acetaminophen (Tylenol®) or ibuprofen (Advil®) and prescription opioids.
  • Analog – Drugs that are similar in chemical structure or pharmacologic effect to another drug, but are not identical.
  • Benzodiazepines – Sometimes called “benzos,” these are sedatives often used to treat anxiety, insomnia, and other conditions. Combining benzodiazepines with opioids increases a person’s risk of overdose and death.
  • Chronic pain – Pain that lasts 3 months or more and can be caused by a disease or condition, injury, medical treatment, inflammation, or an unknown reason.
  • Drug misuse – The use of illegal drugs and/or the use of prescription drugs in a manner other than as directed by a doctor, such as use in greater amounts, more often, or longer than told to take a drug or using someone else’s prescription.
  • Drug addiction – The preferred term is substance use disorder. When referring to opioids, see the Opioid Use Disorder (OUD) definition below and text box discussing the difference between “tolerance,” “dependence,” and “addiction.”
  • Extended-release/long-acting (ER/LA) opioids – Slower-acting medication with a longer duration of pain-relieving action.
  • Fentanyl – Pharmaceutical fentanyl is a synthetic opioid, approved for treating severe pain, typically advanced cancer pain. It is 50 to 100 times more potent than morphine. However, illegally made fentanyl is sold through illicit drug markets for its heroin-like effect, and it is often mixed with heroin or other drugs, such as cocaine, or pressed in to counterfeit prescription pills.
  • Heroin – An illegal, highly addictive opioid drug processed from morphine and extracted from certain poppy plants.
  • Illicit drugs – The nonmedical use of a variety of drugs that are prohibited by law. These drugs can include: amphetamine- type stimulants, marijuana/cannabis, cocaine, heroin, other opioids, and synthetic drugs, such as illicitly manufactured fentanyl (IMF) and ecstasy (MDMA).
  • Immediate-release opioids – Faster-acting medication with a shorter duration of pain-relieving action.
  • Medication-assisted treatment (MAT) – Treatment for opioid use disorder combining the use of medications (methadone, buprenorphine, or naltrexone) with counseling and behavioral therapies.
  • Morphine milligram equivalents (MME) – The amount of milligrams of morphine an opioid dose is equal to when prescribed. Calculating MME accounts for differences in opioid drug type and strength.
  • Naloxone – A drug that can reverse the effects of opioid overdose and can be life-saving if administered in time. The drug is sold under the brand name Narcan or Evzio.
  • Narcotic drugs- Originally referred to any substance that dulled the senses and relieved pain. Some people use the term to refer to all illegal drugs but technically, it refers only to opioids. Opioid is now the preferred term to avoid confusion.
  • Nonmedical use – Taking prescribed or diverted prescription drugs (drugs not prescribed to the person using them) not in the way, for the reasons, in the amount, or during the time-period prescribed.
  • Non-opioid therapy – Methods of managing pain that does not involve opioids. These methods can include, but are not limited to, acetaminophen (Tylenol®) or ibuprofen (Advil®), cognitive behavioral therapy, physical therapy, acupuncture, meditation, exercise, medications for depression or for seizures, or interventional therapies (injections).
  • Non-pharmacologic therapy – Treatments that do not involve medications, including physical treatments (e.g., exercise therapy, weight loss) and behavioral treatments (e.g., cognitive behavioral therapy).

    “Opiates” vs. “opioids” Although these terms are often used interchangeably they are different:

    Opiates refer to natural opioids such as heroin, morphine and codeine.

    Opioids refer to all natural, semisynthetic, and synthetic opioids.

  • Opioid – Natural, synthetic, or semi-synthetic chemicals that interact with opioid receptors on nerve cells in the body and brain, and reduce the intensity of pain signals and feelings of pain. This class of drugs includes the illegal drug heroin, synthetic opioids such as fentanyl, and pain medications available legally by prescription, such as oxycodone, hydrocodone, codeine, morphine, and many others. Prescription opioids are generally safe when taken for a short time and as directed by a doctor, but because they produce euphoria in addition to pain relief, they can be misused and have addiction potential.
  • Opioid analgesics – Commonly referred to as prescription opioids, medications that have been used to treat moderate to severe pain in some patients. Categories of opioids for mortality data include:
    • Natural opioid analgesics, including morphine and codeine;
    • Semi-synthetic opioid analgesics, including drugs such as oxycodone, hydrocodone, hydromorphone, and oxymorphone;
    • Methadone, a synthetic opioid that can be prescribed for pain reduction or for use in MAT for opioid use disorder (OUD). For MAT, methadone is used under direct supervision of a healthcare provider;
    • Synthetic opioid analgesics other than methadone, including drugs such as tramadol and fentanyl.
  • Opioid use disorder (OUD) – A problematic pattern of opioid use that causes significant impairment or distress. A diagnosis is based on specific criteria such as unsuccessful efforts to cut down or control use, or use resulting in social problems and a failure to fulfill obligations at work, school, or home, among other criteria. Opioid use disorder is preferred over other terms with similar definitions, “opioid abuse or dependence” or “opioid addiction.”
  • Overdose – Injury to the body (poisoning) that happens when a drug is taken in excessive amounts. An overdose can be fatal or nonfatal.
  • Physical dependence – Adaptation to a drug that produces symptoms of withdrawal when the drug is stopped.
  • Prescription drug monitoring programs (PDMPs) – State or territorial-run electronic databases that track controlled substance prescriptions. PDMPs help providers identify patients at risk of opioid misuse, opioid use disorder, and/or overdose due to overlapping prescriptions, high dosages, or co-prescribing of opioids with benzodiazepines.
  • Tolerance – Reduced response to a drug with repeated use.
What is the difference between “tolerance,” “dependence,” and “addiction”?

Opioid tolerance occurs when a person using opioids begins to experience a reduced response to medication, requiring more opioids to experience the same effect.

Opioid dependence occurs when the body adjusts its normal functioning around regular opioid use. Unpleasant physical symptoms occur when medication is stopped.

Opioid addiction (Opioid use disorder (OUD)) occurs when attempts to cut down or control use are unsuccessful or when use results in social problems and a failure to fulfill obligations at work, school, and home. Opioid addiction often comes after the person has developed opioid tolerance and dependence, making it physically challenging to stop opioid use and increasing the risk of withdrawal.

CDC Guideline for Prescribing Opioids for Chronic Pain