Opioids are a class of drugs that includes heroin, hydrocodone, oxycodone, and other morphine-derived drugs. Use of such drugs can cause tolerance, dependence, and addiction, and for some people, result in what is referred to as opioid use disorder (OUD).
Opioid Tolerance
Opioid tolerance occurs when a person using opioids begins to experience a reduced response to the medication, requiring more opioids to experience the same effect. Psychological tolerance can develop quickly, meaning a user must take more of the medication to achieve the same effect, often in doses significantly higher than a therapeutic dose. In contrast, analgesic tolerance develops slowly and patients with stable pain may be able to stay on the same dose for months or years.
Opioid Dependence
Opioid dependence occurs when the body adjusts its normal functioning around regular opioid use (CDC, 2021, January 26). Dependence is often part of addiction, but they are not the same thing.
If a drug is abruptly reduced or stopped, those who are dependent experience unpleasant physical withdrawal symptoms. Depending on the drug, these symptoms can be mild to severe and can usually be managed medically—or avoided by slowly tapering the drug dosage downward (NIDA, 2020, June). Dependence can resolve after medically supervised withdrawal (formerly called detoxification).
Opioid Addiction
Opioid addiction 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. Addiction often comes after a person has developed opioid tolerance and dependence, making it physically challenging to stop opioid use and increasing the risk of withdrawal (CDC, 2021, January 26).
Addiction is a treatable, chronic medical disease involving complex interactions among brain circuits, genetics, the environment, and an individual’s life experiences. People addicted to opioids use substances or engage in behaviors that become compulsive and often continue despite harmful consequences (ASAM, 2019).
Prevention efforts and treatment approaches for addiction are generally as successful as those for other chronic diseases (ASAM, 2019). As with other chronic diseases, addiction often involves cycles of relapse and remission. Without treatment or engagement in recovery activities, addiction is progressive and can result in disability or premature death (ASAM, 2015).
Understanding the difference between dependence and addiction provides a better grasp of the issues related to opioid use and abuse.
Opioid Use Disorder
The DSM-5 defines opioid use disorder (OUD) as a disorder characterized by loss of control of opioid use, risky opioid use, impaired social functioning, tolerance, and withdrawal. Tolerance and withdrawal do not count toward the diagnosis in people experiencing these symptoms when using opioids under appropriate medical supervision. OUD covers a range of severity and replaces what DSM-IV termed opioid abuse and opioid dependence.
Generally, those who are dependent on opioids vary between feeling sick without the drug and feeling the desired high after taking the drug. Being addicted to the drug (having OUD) motivates a person to do whatever it takes to get and take the drug in order to avoid withdrawal symptoms. Prescription Drug Monitoring Programs (PDMPs) are designed to identify patients who are drug-seeking or at risk for opioid use disorder.
People with opioid use disorder who follow detoxification with complete abstinence are likely to relapse. While relapse is a normal step on the path to recovery, it can also be life threatening, raising the risk for a fatal overdose. An important way to support recovery from heroin or prescription opioid use disorder is to maintain abstinence from those drugs (NIDA, 2018, June).