Drug tests are widely used to indicate the presence of certain substances in the body. Depending on available resources, drug tests can be completed using urine, saliva, hair, or blood samples. For optimal reliability, drug tests should involve a screening (immunoassay). Positive immunoassay results should be confirmed with a GC-MS (Gas Chromatography-Mass Spectrometry) test.
- The overall rate of positive urine drug tests stayed the same between 2021 and 2022. However, changes in marijuana legalization have led to a rise in positive marijuana drug test results.
- In order to be considered reputable, laboratory drug tests should consist of an initial screening followed by a more precise test to verify any positive results.
- While mostly reliable, at-home drug tests may incorrectly yield preliminary positive results. Urine samples should be sent to a laboratory for confirmation if this occurs.
- How and where drug tests can be performed varies with individual state law, with some states offering more freedom for randomized drug testing than others.
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Understanding drug tests
A drug test is intended to identify any misuse of illegal substances or prescription drugs. Drug tests use samples of urine, saliva, sweat, blood, and hair to detect traces of specific drugs through immunoassay testing.[1]
These drug tests are most often used to detect the use of illegal substances such as cocaine or methamphetamines, but can also be used to detect the misuse of prescription drugs such as opioid painkillers or benzodiazepines, as well as general substances of abuse such as alcohol.[1]
Drug tests or screens can detect specific substances or can be used to identify a broad range of substances, depending on the type of test used.
- Common drugs screened for in tests include:[1]
- Alcohol
- Amphetamines (meth)
- Barbiturates (amobarbital)
- Benzodiazepines (Xanax, Valium, etc)
- Cocaine
- Marijuana (THC)
- Opioids (heroin, oxycodone, hydrocodone, codeine, fentanyl)
- Phencyclidine (PCP)
- Steroids
These are the drugs that are most commonly tested using what is called a 10-panel drug test. Other types of drug tests screen for more substances, such as 14-panel tests, and others that look for smaller groups of drugs but with more concrete results, such as 5-panel tests.
Other names for drug tests
Drug screen, drug test, drugs of abuse testing, substance abuse testing, immunoassay testing, toxicology screen, tox screen, and sports doping tests are all terms that are used to describe drug tests. However, it is important to note that there is a difference between drug testing and drug screening.
Drug testing vs screening
While the two terms may be used interchangeably, there is a difference between drug testing and drug screening. To be considered reputable, the drug testing process should consist of two steps. The first step is called an immunoassay, which involves measuring the presence of a certain substance in the blood based on reactions from immune system markers such as antibodies and antigens.[5]
Since this is a less precise measure, the immunoassay is considered a screening. If someone’s immunoassay results are negative, they are considered to be negative for the presence of the drugs tested, and the testing ends there.
However, if someone receives a positive result from the screening, laboratory professionals will then perform a confirmatory test using alternative methods. The confirmatory process measures a different blood sample through gas chromatography-mass spectrometry (called a GC-MS test).[5][1]
This second test is considered much more precise, meaning it is extremely unlikely to produce a false negative or false positive result. Therefore, to accurately determine whether or not drugs are present in someone’s blood, it is important to perform both screening and testing.
Drug testing facts
All information shown is from analysis reported by Quest Diagnostics:[2][6][8]
- In 2024, the industries with the highest positivity rates were retail and other services, both coming in at 5.9%.
- The highest marijuana positivity rates (8%) were seen in retail workers, with those in real estate, rental, and leasing coming in next highest at 6.2%.
- Overall positivity rates for cocaine are much lower; the highest rates for this substance (0.39%) were within the construction industry.
- Healthcare and social assistance workers tested positive for opiates more often than other industries, with a positivity rate of 0.19%.
- Individuals working within educational services had the highest positivity rate for amphetamines (2.2%), including amphetamine and methamphetamine.
- Individuals in educational services had the lowest positivity rates for marijuana (1.8%) and cocaine (0.05%,) while those in transportation and warehousing had the lowest positivity rates for opiates (0.05%) and amphetamines (0.74%).
- Out of the federally mandated urine drug tests performed this year, a total of 2.3% were positive.
- The positivity rates in the general U.S. workforce were more than double the rate of those that were federally mandated (5.6%).
- In 2024, a total of 12.6% of urine drug tests were completed for cause. This means workplace administrators had justification to perform a drug test on certain individual(s).
- 4.5% of all drug tests performed in 2024 were due to an accident. These numbers have remained relatively consistent over the years, ranging between 4.3% and 4.6% since 2020.
Types of drug test
While urine testing is the most common form of drug test owing to its ease of use, relative accuracy, and ready availability, there are several other types of drug tests used for specific drug screening or further accuracy. These include:
Panel drug tests
A panel drug test is a normal drug test; the “panel” refers to the number of drugs being screened for. For example, a 5-panel screening will test for 5 specific drugs, and a 12-panel screening will test for 12. Most home drug panel test kits are performed with urine sampling for ease and accuracy, though other samples are also used in lab settings. Learn more about the different types of drug panel tests here:
At-home drug tests
Due to their convenience, at-home drug tests are becoming more common. They test someone’s urine for the presence of certain drugs, not the quantity of any substances that have been found.
At-home drug tests involve initially testing the urine yourself. If this portion of the test yields a preliminary positive result, you must send the same urine sample to a laboratory for further testing.[3]
Preliminary positive at-home drug test results can occur due to certain prescription medications, dietary supplements, and even foods or beverages consumed just before the test. Other factors, such as not following the test directions properly and mishandling or improperly storing the urine sample or the test, can also lead to preliminary positive results in the absence of drug use.[3]
While at-home drug tests are considered fairly sensitive, their accuracy can be impacted by any of the above factors. Therefore, it is essential to send any preliminary positive urine samples to the laboratory in order to confirm test results.
Drugs that don't show up on screening tests
While 5, 10, and 15-panel tests are designed to detect the most common and easily identifiable drugs, many substances are difficult to detect or can’t be detected at all. These include;
- Psychedelics/hallucinogens - substances such as LSD, psilocybin, DMT, and mescaline are extremely difficult, if not impossible, to detect in drug screenings as they are metabolized extremely quickly. Hair follicle tests may be used to detect psychedelics, but this is rare, as they are expensive and time-consuming.
- GHB - Gamma hydroxybutyrate, better known as GHB or the date rape drug, is almost completely undetectable in the system within 12 hours of consumption. This makes it hard to determine if it was used in cases of date rape, making convictions difficult.
- Designer drugs - Research chemicals or designer drugs are compounds found in various synthetic substances (such as bath salts or “spice”) that are very hard to detect with standard drug tests. These substances are often highly modified to give unique highs or to mimic the effects of other substances, such as meth or cocaine.
When you may be required to do a drug test
Drug testing is used in many areas to identify drug misuse, such as by employers, sporting institutions, academic settings, and in legal cases. Despite popular misconceptions, drug tests are not used to identify a substance use disorder, addiction, or dependence. How and where drug tests can be performed varies with individual state law, with some states offering more freedom for randomized drug testing than others.[4]
Common areas drug tests are used for include:
- Employment - It is becoming increasingly prevalent for employers to screen candidates for substance abuse with drug tests before employing. Some employers also perform regular drug tests throughout employment, as well as testing after a work-related accident, to ensure drugs or alcohol were not involved. For a full rundown on how to create a drug-free workplace, visit our Drug and Alcohol Resources for Employers page.
- Sports - Professional athletes are often screened for performance-enhancing drugs such as steroids or any other substance that may give them an edge in competition.
- Law enforcement - There are several instances in which a drug test may be used in legal settings. This includes breathalyzing suspected DUI drivers, as part of evidence in a court case, random prison screenings, and others.
- Entering drug treatment - Addiction treatment centers will often screen new patients to identify what substances they may currently have in their system. This is especially important for those undergoing medically assisted detox, as it will ensure the correct course of medication can be administered safely.
- Monitoring prescription drug use - A doctor may order a drug test if you are on a course of medication that is potentially addiction-forming or if you have a history of drug abuse.
- Educational settings - Some schools and higher education settings have the right to administer drug tests if they have reasonable doubt about a student's potential drug use. Drug testing in educational settings is often more common in student-athletes, especially those on a sports scholarship.
- The military - Recruits and soldiers may be randomly tested for drugs to make sure they are combat effective.
In all of the above cases, drug tests may be scheduled in advance or ordered randomly without advanced warning. Read here to learn more about how drug tests work.
Drug tests and young people
In some cases, such as in schools, random drug tests are performed. Since individuals in K-12 settings are underage, it is important for professionals to be aware of ethical and legal considerations that may impact testing procedures.
If a child or adolescent is considered competent and able to make their own decisions, professionals are required to obtain their consent before drug testing.[7] However, there are instances when the consumption of substances (e.g., drugs or alcohol) may impair someone’s cognitive abilities.
In this case, healthcare professionals should use their clinical judgment to determine if the youth is at risk of injury, illness, or other safety concerns. If this risk is present, a clinician may conduct a urine drug test on a young person without consent as part of a comprehensive medical assessment.[7]
Preparing for a drug test
Most drug tests are performed at random so that those being tested don’t have time to influence the results. To ensure that results are read as accurately as possible, it is important to be 100% honest and clear with whoever is administering the test about any substances or over-the-counter medications you have taken, so that test results are read clearly.
You should also avoid certain foods and herbal remedies that may generate a false positive on a test. Food and drug products that may interfere with drug tests include poppy seeds (for opioid tests), hemp products (marijuana), sleep aids (barbiturates), hay fever remedies (amphetamines), and diet pills (amphetamines).[5]
Be sure to know the reason you are being tested and what you are being tested for before you start. Seek any additional information from the test provider or organization asking for the test if you are unsure or uncomfortable.
Understanding drug test results
A negative result for any drug test indicates that none of the drugs screened for were identified or that their presence was below the cutoff point in the person's system.[4]
A positive result means that a substance or substances were detected in the system. A positive result will often require a follow-up test to either determine more accurately what drugs were detected or to rule out a false positive result.
If a positive result comes in for a drug you are prescribed by your doctor, such as benzodiazepines, your employer cannot legally penalize you. This does not apply to marijuana, even if it is legal in your state, and your employer has the right to penalize you if it falls within their drug policy to do so.
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