A drug test involves testing a biological sample, such as urine or hair, for the presence of a legal or illegal drug. There are several possible uses for a drug test, the most common of which is for pre-employment screening. The most commonly tested drugs include amphetamines, cocaine, marijuana, opioids and PCP.
A drug test uses a biological sample (such as blood or urine) to detect the presence or absence of a legal or illegal drug. Drug tests are ordered and performed in a variety of settings with a variety of techniques.
Drugs include legal substances such as alcohol and tobacco, as well as over-the-counter medications, prescription medications and illegal substances. A single drug test can’t determine the frequency and intensity of substance use and, thus, can’t distinguish casual substance use from substance use disorders.
Your body metabolizes (breaks down) various drugs at different rates, so the timeframe for detecting certain drugs in your system can be very specific and vary widely from substance to substance.
Urine drug testing (UDT) is the most common test for detecting drugs.
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You may need a drug test for several reasons. The most common use of drug testing is in the workplace. Employers may require a drug screening for various reasons, including:
Another common use of drug testing is for the diagnosis, treatment and monitoring of alcohol use disorder and substance use disorder. As a tool for monitoring, drug testing can help determine treatment adherence, monitor abstinence and detect early relapse.
You may need this testing for court-ordered treatment programs, as a term of probation or while participating in a substance use disorder treatment program.
Other uses for drug testing include:
There are several kinds of drug tests based on the biological sample they use and the types of drugs they detect.
Different types of drug tests based on the sample used include:
When a drug enters your body, your gastrointestinal tract absorbs and distributes it to the rest of your body. Your liver and other organs metabolize the drug (break it down). Metabolic processes cause the drug to turn into different chemicals, called metabolites. After a certain amount of time, the drug and/or its metabolites leave your body, mainly through your urine.
A drug test screens for certain drugs and/or their metabolites in a biological sample (such as urine or blood).
The metabolic processes happen at different speeds for different drugs. Because of this, each drug and its metabolites have a different timeframe in which a drug test can detect them.
For some drugs like amphetamines, the main (parent) drug will be detected in urine. For most other drugs, metabolites will be detectable for a longer time than the main drug.
A drug test may look for only one drug, but most drug tests often test for multiple drugs with one sample. Although the drugs included in a drug panel test vary based on the reason for the test, the most common panel used to evaluate people for illegal drug use detects the presence or absence of five substances:
Other commonly tested substances include:
Yes. Some kits can test urine samples in the privacy of your own home. Some kits may use breath, saliva or hair instead. The accuracy of these products is variable. They generally are less sensitive than the formal tests done in a laboratory. This means that a home test could be negative, but a laboratory test could be positive with the same sample.
The American Academy of Pediatrics cautions parents against drug testing their children at home. Research studies have shown that at-home testing doesn’t reduce drug use. At-home testing also comes with the potential for misinterpreting results, which may negatively affect the relationship between children and parents.
There’s nothing you need to do to prepare for a drug test.
Drug testing can be an emergency test, a scheduled test or it may be conducted randomly (for example, to meet ongoing employment requirements).
Depending on the circumstances, you may be asked to identify medications or supplements you’re taking.
Drug testing can be performed from small samples of your blood, hair, saliva, breath or, most commonly, your urine (pee).
For a urine sample, you’ll pee into a clean container provided to you. In some instances, you may need to provide your urine sample in the presence of a nurse or technician to make sure that the sample did indeed come from you.
For a blood sample, a phlebotomist will draw a small amount of blood from a vein in your arm or hand.
After the provider has collected the sample, they’ll send it to a laboratory for analysis
The time it takes to get the results of a drug test varies based on the reason for the test (for example, if it’s for an emergency or employment screening) and the type of drug test.
Urine and blood drug tests usually have a quicker turnaround time for results than hair drug testing.
Ask the institution that requested the drug test about when you can expect results.
Drug test results are typically reported as positive or negative.
A positive result indicates that a drug was detected at or above the reference range for that test. A negative result indicates that the drug wasn’t detected or was below the threshold for a positive test result.
There are several considerations to remember when understanding a drug test’s results.
A positive result on a drug test simply means that the person had a detectable amount of a substance present during a certain window of time. A positive result doesn’t necessarily mean that the person is currently intoxicated or experiencing the effects of the substance. A positive result also doesn’t necessarily mean that the person has a substance use disorder.
Positive results on an initial drug test usually need to be confirmed with additional testing. Confirmatory testing uses a different type of drug test. It improves the accuracy of the overall drug testing by reducing the risk of false-positive results (when someone tests positive for a drug even though they never used it).
Medications and certain foods may produce false-positive results. For example, consuming poppy seeds can cause a positive opioid test result, and taking over-the-counter cold medicine can cause a positive result for PCP.
A negative result on a drug test simply means that the particular substance couldn’t be detected. This could be because its level wasn’t sufficient enough to be detected or that the substance use didn’t happen during the detection window. A negative result doesn’t, however, rule out recent substance use or a substance use disorder.
False-negative results (when a person tests negative for drugs despite drug use or misuse) can happen for several reasons, including:
A note from Cleveland Clinic
Drug testing has a wide range of applications. Though it can be stressful to get a drug test, know that healthcare providers and officials carefully analyze and interpret the results. In most cases, a positive drug test result requires another test, known as a confirmatory test, to rule out a possible false-positive result. If you have questions about the drug test process or when to expect results, talk to the person in charge of ordering the test.
Last reviewed by a Cleveland Clinic medical professional on 08/05/2022.
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