A
Addiction
A chronic brain disease affecting the reward, motivation, and memory systems, characterized by compulsive substance use despite harmful consequences.
Adverse Reaction
An unexpected or harmful physical or psychological response that occurs after taking a specific drug or medication. Adverse reactions range in severity from mild side effects to life-threatening events and are an important factor in monitoring a patient’s treatment plan.
Age at Onset
The specific age at which a person first exhibits symptoms associated with a condition. Earlier onset is often associated with greater severity and more complex treatment needs.
Agonist
A chemical substance that binds to specific receptors in the brain and activates them to produce a biological response. Opioid agonists such as methadone and fentanyl replicate the effects of opioids.
Agonist / Partial Agonist
An agonist activates brain receptors fully, while a partial agonist produces a weaker, ceiling-limited response. Buprenorphine is a well-known partial agonist used in opioid treatment.
Amphetamine
A potent central nervous system stimulant prescribed for ADHD and narcolepsy. Carries a high risk of misuse and dependence due to dramatic increases in dopamine levels.
Analgesic
Any medication formulated to relieve pain without causing loss of consciousness. Opioid analgesics carry a significant risk of dependence and misuse.
Antagonist
A drug or chemical that binds to a receptor and blocks it. Naloxone and naltrexone are examples used in addiction medicine.
AOD (Alcohol and Other Drugs)
A standard abbreviation used in addiction treatment and public health to refer collectively to alcohol and all other psychoactive substances.
Assessment
A formal professional evaluation of a person’s medical, psychological, and social history conducted to determine the nature and extent of their substance use and to guide treatment decisions.
B
Barbiturate
A class of sedative-hypnotic drugs that depress the central nervous system. Largely replaced by safer alternatives due to a narrow margin between therapeutic and fatal doses.
Bath Salts
A street name for synthetic designer drugs containing substituted cathinones. Carry an elevated risk of overdose, severe agitation, hallucinations, and organ failure.
Benzodiazepine (Benzos)
A class of prescription psychoactive drugs that slow brain activity. Carry a risk of physical dependence and can be fatal in high doses, especially when combined with opioids.
Binge Drinking
A pattern of alcohol consumption defined as five or more standard drinks on one occasion for men, or four or more for women, raising BAC to 0.08 g/dL or higher.
Blood Alcohol Level / Concentration (BAC)
The percentage of alcohol present in a person’s bloodstream at a given time. In the United States, a BAC of 0.08% or higher constitutes impairment for drivers.
C
Ceiling Effect
The point at which increasing a drug’s dose no longer produces any additional therapeutic benefit. Buprenorphine has a ceiling effect on respiratory depression, making it safer than full opioid agonists at higher doses.
Central Nervous System (CNS)
Consists of the brain and spinal cord and serves as the body’s primary control network. Many addictive substances achieve their effects by altering chemical signaling within the CNS.
Chemical Dependency
A term used interchangeably with addiction to describe a state in which physical and psychological functioning has become reliant on a substance.
Chemical Dependency Treatment Facility
A licensed healthcare setting authorized to provide professional assessment and treatment for substance use disorders.
Clinical Decision Support
Electronic systems or tools that provide healthcare providers with personalized, evidence-based information at the point of care to improve treatment decisions.
Clinical Opiate Withdrawal Scale (COWS)
An 11-item assessment tool used by clinicians to measure the severity of opioid withdrawal symptoms in real time, guiding the timing and dosing of medications like buprenorphine.
Clinical Trial
A carefully designed research study in which human participants are assigned to interventions to evaluate their safety and effectiveness.
Codeine
A naturally occurring opioid used to treat mild to moderate pain and suppress coughing. Carries a real risk of dependence and misuse.
Coinsurance
The percentage of a covered medical service’s cost that a patient is responsible for paying after meeting their annual deductible.
Compulsivity
The repetitive engagement in behaviors despite knowing they are harmful. Driven by neurological changes in the brain’s reward and control circuits.
Continuum of Care
A coordinated system of services designed to meet a patient’s evolving needs across different levels of treatment intensity, from initial detox through outpatient therapy and long-term recovery maintenance.
Copayment
A fixed dollar amount a patient pays for a specific covered healthcare service, usually collected at the time of the visit.
Cost-Benefit Study
Evaluates a treatment by converting both its costs and measurable benefits into monetary terms to determine whether the benefits outweigh the investment.
Cost-Effectiveness Study
Compares two or more treatment approaches based on how much it costs to achieve a specific health outcome.
Craving
An intense, often overwhelming urge to use a substance, driven by neurological changes in the brain’s reward and memory systems.
Cross Tolerance
Occurs when repeated use of one substance reduces sensitivity to a pharmacologically similar substance.
D
DEA (Drug Enforcement Administration)
The primary U.S. federal law enforcement agency responsible for combating illegal drug manufacture, trafficking, and distribution. Also regulates prescribing of controlled substances.
Deductible
The amount a person must pay out-of-pocket for covered health services within a plan year before their insurance begins to contribute.
Denial
A psychological defense mechanism in which a person is unable or unwilling to acknowledge the severity of their substance use problem.
Dependence
A physiological state in which the body has adapted to the regular presence of a substance and requires it to function normally. Distinct from addiction.
Depressant
A class of substances that slows central nervous system activity. Includes alcohol, benzodiazepines, and barbiturates. In high doses, can dangerously suppress respiration.
Detoxification (Detox)
The medically supervised process of safely eliminating addictive substances from the body while managing withdrawal symptoms. Typically the first step in addiction treatment.
Diagnostic Evaluation
A formal clinical assessment using standardized criteria such as those in the DSM-5 to determine whether an individual meets the diagnostic threshold for a substance use disorder.
Doctor-Shopping
The practice of visiting multiple physicians without their knowledge in order to obtain more prescriptions for controlled substances. Illegal under state and federal law.
Dopamine
A neurotransmitter central to the brain’s reward system. Addictive substances work by flooding the brain with dopamine, reinforcing drug-taking behavior.
Downers
An informal term for depressant drugs including alcohol, benzodiazepines, barbiturates, and tranquilizers. Carry a significant risk of dependence and can be fatal in overdose.
Driver Alcohol Education (DAE)
A state-supervised educational intervention for individuals convicted of a first-time drunk driving offense, combining substance use education with assessment.
Drug Diversion
The illegal transfer or misuse of a legally prescribed controlled substance. Contributes significantly to the opioid epidemic.
Drug of Choice (DOC)
A clinical term referring to the primary substance for which a person is seeking treatment.
Drug Tolerance
A pharmacological phenomenon in which the body adapts to repeated exposure to a substance, requiring progressively higher doses to achieve the same effect.
DUI / DWI
Legal terms for operating a motor vehicle while impaired by alcohol or any substance. Both carry serious criminal penalties.
E
Enabling
When well-intentioned actions inadvertently shield someone with an addiction from facing the results of their substance use, ultimately removing the motivational pressure to seek treatment.
Ethanol
The type of alcohol found in all alcoholic beverages. Acts as a central nervous system depressant. Long-term excess consumption causes liver disease, neurological damage, and cardiovascular problems.
H
Health Care System
All the people, institutions, funding mechanisms, and activities organized to improve and maintain the health of a defined population.
Health Disparities
Preventable differences in the burden of disease, access to care, and health outcomes experienced by historically marginalized populations.
Heavy Drinking
Clinically defined as consuming more than 8 standard drinks per week for women or more than 15 for men, according to the CDC.
Heroin
An illegal, highly addictive opioid synthesized from morphine. Carries extreme risks including overdose, death, and transmission of bloodborne diseases.
HIPAA
The Health Insurance Portability and Accountability Act of 1996, establishing national standards for protecting patients’ medical information. Particularly relevant in addiction treatment.
I
Impulsivity
A tendency to act quickly on urges without fully considering the consequences. Both a risk factor for and a symptom of substance use disorder.
Inhalant
Any volatile chemical substance that is inhaled to produce intoxicating effects. Can cause permanent neurological damage, cardiac arrest, or sudden death even with first-time use.
In-Network
A healthcare provider or facility that has a contractual agreement with a health insurance company to provide services at pre-negotiated rates.
Intensive Outpatient Program (IOP)
A structured addiction treatment service providing several hours of therapy per day, typically three-hour sessions, three to five days per week, without requiring overnight hospitalization.
J
Joint Commission
An independent nonprofit organization that accredits and certifies hospitals and behavioral health facilities. Accreditation signals compliance with national standards for patient safety and quality of care.
L
Longitudinal Study
A research design in which the same group of individuals is tracked repeatedly over an extended period to understand how substance use develops and treatment effects evolve.
M
Meaningful Use
A federal standard defining how healthcare providers should use electronic health record technology to improve care quality, patient safety, and data exchange.
Medicaid
A joint federal and state government program providing free or low-cost health coverage. Required under the Affordable Care Act to cover substance use disorder treatment as an essential health benefit.
Medicare
A federal health insurance program primarily serving Americans aged 65 and older. Covers inpatient detox, outpatient therapy, and medications for opioid use disorder.
Morphine
A naturally occurring opioid alkaloid and one of the most potent analgesics in clinical medicine. Carries a high risk of dependence.
N
Narcotic
A substance that produces pain relief and altered consciousness by acting on opioid receptors. All prescription opioids are classified as narcotics.
Negative Reinforcement
The process by which drug use is strengthened because it removes something unpleasant, such as withdrawal symptoms or emotional pain.
Net Economic Benefit
An analysis calculating the total monetary value of an intervention’s benefits minus its total costs.
O
Opiate
A substance derived directly from the opium poppy plant, including morphine, codeine, and heroin.
Opioid
Any substance, natural, semi-synthetic, or fully synthetic, that binds to opioid receptors to produce pain relief, sedation, and euphoria.
Out of Network
A healthcare provider or facility that does not have a contract with a patient’s health insurance plan, typically resulting in higher out-of-pocket costs.
Out of Pocket
The expenses for healthcare services that a patient pays directly, including deductibles, copayments, and coinsurance.
Outpatient Rehab
A form of addiction treatment allowing individuals to live at home while attending scheduled therapy sessions. Appropriate for mild to moderate substance use disorders with stable living situations.
Over-the-Counter Drugs (OTC)
Medications purchasable without a prescription. Some OTC medications are misused for psychoactive effects and carry a risk of dependence.
P
Partial Hospitalization Program (PHP)
A structured, intensive outpatient treatment level providing psychiatric and addiction services during daytime hours, typically 6 to 8 hours per day, 3 to 7 days per week.
Pharmacogenetics
The study of how an individual’s genetic makeup influences their response to medications, including those used in addiction treatment.
Pharmacokinetics
The study of how the body processes a drug after it is administered, including absorption, distribution, metabolism, and excretion.
Positive Reinforcement
The process by which drug use is repeated because it produces a pleasurable outcome, driven largely by dopamine release.
Post-Acute Withdrawal Syndrome (PAWS)
A cluster of psychological and cognitive symptoms, including mood swings, anxiety, and irritability, that persist for weeks or months after the acute physical withdrawal phase has ended.
Precipitated Withdrawal Syndrome
A rapid and severe onset of withdrawal symptoms triggered when an opioid antagonist or partial agonist is administered before sufficient opioids have cleared the system.
Premium
The fixed monthly amount an individual or employer pays to maintain active health insurance coverage.
Prescription Drug Misuse
The use of any prescription medication in a way that differs from how it was prescribed.
Prevalence
A statistical measure describing the proportion of a given population that has a particular condition at a specific point in time.
Q
Quality-Adjusted Life Year (QALY)
A standardized metric combining quantity of life with quality of life to measure the value of medical interventions.
R
Randomized Controlled Trial (RCT)
The gold standard research design in which participants are randomly assigned to a treatment or control group to evaluate the effectiveness of an intervention.
S
Spice (Synthetic Marijuana)
A street name for synthetic cannabinoids. Despite being marketed as safe, they carry unpredictable potency and can cause psychosis, heart attack, and seizure.
Stimulant
A class of drugs that increases central nervous system activity. Common stimulants include cocaine, amphetamines, and methamphetamine.
Structured Outpatient Addiction Program (SOAP)
A clinically intensive, short-term outpatient service designed for individuals who need more structure than standard outpatient therapy but do not require 24-hour residential support.
Substance
Any psychoactive compound, including alcohol, prescription medications, and illicit drugs, that can alter brain function and carries potential for health problems or dependence.
Substance Abuse
A pattern of substance use that causes significant harm without necessarily meeting the full criteria for dependence. Largely replaced in clinical settings by “substance use disorder.”
Substance Dependence
A state in which a person’s body has physiologically adapted to a drug, requiring its continued presence to function normally.
Substance Misuse
The use of any alcohol, prescription medication, or illicit drug in a manner that poses a risk of harm. A broader, non-stigmatizing term.
Substance Use Disorder (SUD)
The current clinical diagnosis for addiction, defined by the DSM-5 as a pattern causing significant impairment across 11 specific criteria, classified as mild, moderate, or severe.
U
Uppers
Informal slang for stimulant drugs including amphetamines, cocaine, and methamphetamine. Carry a significant risk of dependence and cardiovascular damage.
W
Withdrawal
The range of physical and psychological symptoms that occur when a person who is dependent on a substance abruptly reduces or stops using it. Medically supervised detox improves safety and comfort.