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What Are Drugs?

Drugs are chemicals or plant products that affect the mind and body. Drugs include legal substances such as alcohol and tobacco, as well as over-the-counter medications, prescription medicines, and illegal substances.

When used appropriately, prescription and over-the-counter medicines treat medical conditions and improve a person’s health. However, problematic usage of drugs can lead to health risks, including addiction. Substance use can be separated into two general categories, depending on how the drug is obtained:

  • Drug use: Drug use refers to using any illegal drug. People who use these substances ingest, inhale, smoke, or inject them into their bodies. Illegal drugs are often used for their mind-altering characteristics but may be taken for other purposes, such as weight loss or enhancing athletic performance.
  • Drug misuse: Drug misuse refers to the use of medication in a way that is unhealthy or differs from what is recommended by a doctor. Drug misuse includes problematic usage of alcohol, tobacco, and over-the-counter medicines, as well as misuse of prescription drugs.

Drug use and misuse can lead to the development of an addiction. Addiction, also called a substance use disorder, is a chronic disease in which repeated drug use leads to changes in the brain. Addiction is complex, involving the brain, genetics, as well as a person’s environment and life experiences. A person with an addiction continues to use drugs compulsively, despite negative consequences.

Patients concerned about drug use, misuse, or addiction should discuss concerns with their doctor or a mental health professional. There are many effective treatment options for substance use disorders and addiction.

The Role of Drug Tests

Drug testing looks for evidence that a person has used or misused drugs. The most common use of drug testing is in the workplace. Employers may require a drug screening before hiring an applicant. Random or periodic drug testing may also be required after an employee is hired.

Employers may conduct drug testing when drug use is suspected based on symptoms observed in the workplace. An employee may also be tested for drug use after an accident or incident on

the job. Return-to-duty testing is performed after an employee has had an extended absence and is ready to return to the workplace.

Drug screening may be used in many other contexts, including:

  • Legal or forensic testing: Drug testing may be performed as part of an investigation or court case to provide evidence of a crime or in cases of child abuse or endangerment. Additionally, testing may be used to determine if a person is drinking and driving or publicly intoxicated.
  • Medical testing: Patients may be tested for drug use or misuse as part of a medical assessment. For example, patients awaiting an organ transplant may receive drug testing and become ineligible if they receive a positive result. Doctors may also order a drug test for critically ill patients experiencing a potential overdose.
  • Treatment adherence: Drug testing may be ordered to monitor adherence to court-ordered treatment programs, as a term of probation, while participating in a substance abuse treatment program, or as part of an ongoing custody or parental rights case.
  • Monitoring for prescription drug misuse: A doctor may order a drug test to monitor patients who have been prescribed certain drugs that have a potential for misuse, including opioids for pain.
  • Athletic testing: Professional athletes often have to take a drug test to screen for drugs or other substances that are considered performance-enhancing.
  • Military testing: Periodic or random drug tests may be required for members of the military.

Who should get testing?

Drug testing may be required in many contexts, including employment, organized sports, and medication management, as well as police investigations and court cases. Doctors may also recommend a drug test if a patient is receiving treatment for a substance use disorder.

Legal and ethical issues are important when considering the use of drug tests. Because of the sensitive nature of drug testing and potential implications of drug testing results, patients should be provided the opportunity to consent to drug testing whenever possible. Complex legal and ethical questions can arise in specific situations such as:

  • Drug testing minors: Although it’s legal in some locations for a parent to have their child tested for drug use without the child’s consent, the American Academy of Pediatrics recommends that doctors don’t test children for drugs without the child’s knowledge or consent, unless medically necessary.
  • Drug testing during pregnancy: When considering drug testing during pregnancy, it’s important for pregnant patients and their doctors to discuss federal and state patient confidentiality laws and potential consequences if substance use is detected. The American Society of Addiction Medicine recommends that doctors get the consent of pregnant women before drug testing, except during emergencies.

Getting test results

Drug tests are typically reported as positive or negative. Positive results indicate that evidence of a drug was detected at or above the reference range for each test. A negative test result indicates that evidence of the drug was not detected or was below the threshold for a positive test result. There are several considerations to keep in mind when interpreting drug test results:

  • Confirmatory testing may be necessary: Positive results on an initial drug test usually need to be confirmed with additional testing. Confirmatory testing uses a different type of drug test and improves the accuracy of drug testing by reducing the risk of false positive test results, where a person tests positive despite not using a drug.
  • Drug tests may not evaluate intoxication: Positive test results do not always mean that a person is currently intoxicated. Drug tests may detect drugs at a lower threshold than what would be required to produce physical effects. Additionally, some drug tests can detect the use of drugs for days or weeks after use, at which point the drug’s intoxicating effects have subsided.
  • Risk of false positive results: Medications and certain foods may produce false positive results. Examples include poppy seed ingestion causing positive opioid test results and over-the-counter cold medicine resulting in positive PCP test results.
  • Risk of false negative results: False negative results, when a person tests negative for drugs despite drug use or misuse, can occur for several reasons such as improper sample collection or testing, patient attempts to subvert or falsify a drug test, or the use of a drug not evaluated in a specific test. For example, amphetamine testing does not test all types of amphetamines. Commonly used amphetamines, such as MDMA and methamphetamine may not be detected on all amphetamine drug tests.

Types of Drug Tests

There are many types of drug tests. Drug tests differ from one another in the type of drug they detect, the type of sample necessary for testing, and whether they look for the presence of the drug itself or drug metabolites. A drug metabolite is the substance that remains in the body after a drug is broken down (metabolized).

Although urine is the most commonly used test sample for drug testing, drug testing may be performed on a variety of other test samples, including blood, hair, feces, sweat, breath, and saliva. Urine drug testing is often preferred because testing is inexpensive, noninvasive and detects a wide range of drugs. Hair follicle drug testing may be used to test for chronic or long-term drug use.

Drug tests are able to detect evidence of drug use within a specific timeframe called a detection window. Detection windows vary based on many factors, including the length and amount of use and the rate at which the drug is metabolized and eliminated from the body. The following drugs may be included in drug testing:

Drug testing may look for only one drug, but often tests for multiple drugs simultaneously through the use of test panels. Although the drugs included in a drug panel test vary based on the medical facility and location, the most common panel used to evaluate patients for illegal drug use detects evidence of five substances: amphetamines, cocaine, marijuana, opioids, and PCP.

10-panel drug test detects a wider variety of illegal and prescription drugs. In addition to the drugs detected in a 5-panel drug test, a 10-panel drug test detects barbiturates, benzodiazepines, methaqualone, methadone, and propoxyphene.

Getting Drug Tested

Drug testing is performed in a wide variety of settings, including hospitals, laboratories, and other medical settings. Testing may also be conducted at both inpatient and outpatient drug treatment centers.

Patients who are required to receive drug testing should discuss requirements with their employer or program administrator. Other patients interested in drug testing should talk with their doctor to determine if drug testing is appropriate in their case.

At-home testing

At-home drug testing is available for a variety of drugs. When considering at-home drug testing, it’s important to understand that at-home drug testing is not a substitute for testing administered by a health professional and may not include a second confirmatory drug test. Some at-home test kits offer instructions for sending a sample to a laboratory for confirmation testing after a positive result.

Options for at-home drug testing include tests that detect specific drugs, as well as drug panel tests that look for evidence of multiple drugs in one sample.

Parents may be interested in at-home drug testing for children and adolescents. The American Academy of Pediatrics cautions parents against using at-home drug testing in children and adolescents. At-home testing hasn’t been shown to reduce drug use in research studies, comes with the potential for misinterpreting test results, and may negatively affect the relationship between children and parents.

Sources and Resources

Additional resources related to drug use and misuse and drug testing are available in the following links:


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American Society of Addiction Medicine. Definition of addiction. Published 2019. Accessed May 24, 2021. https://www.asam.org/Quality-Science/definition-of-addiction

ARUP Consult. Drug plasma half-life and urine detection window. Published January 2019. Accessed May 24, 2021. https://www.aruplab.com/files/resources/pain-management/DrugAnalytesPlasmaUrine.pdf

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Mahajan G. Urine drug testing for patients with chronic pain. In: Fishman S, ed. UpToDate. Updated November 13, 2019. Accessed May 25, 2021. https://www.uptodate.com/contents/urine-drug-testing-for-patients-with-chronic-pain

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