Marijuana (THC) Testing

Marijuana testing detects evidence of marijuana use. Marijuana, also known as cannabis, is a plant that produces compounds called cannabinoids, such as THC. Cannabinoids have varying effects on the body and may be consumed for medical and recreational purposes.

Marijuana testing is most often performed on a sample of a person’s urine, but may also use samples of blood, saliva, or hair. Testing for marijuana use may be considered for a variety of purposes, including medical screening and employment testing.

Although marijuana use can be tested alone, this test is often combined with other substances as part of a broader screening panel, such as a 10-panel drug test. Positive results of screening panels should be confirmed by a second, more specific confirmation test.

Purpose of the test

A marijuana test is used to detect evidence of marijuana use. Testing for marijuana and other drugs may be performed for many reasons:

• Medical screening: Although it’s not common to screen hospitalized patients for drug use, marijuana testing may be used to assess patients in specialty medical settings, such as psychiatric care and substance use treatment programs.
• Employment testing: Workplaces may require that applicants be tested for the use of marijuana and other drugs. Testing is required by federal law in some workplaces, including transportation and other safety- and security-sensitive industries.
• Military testing: Random drug tests are required by the Department of Defense for members of the military. Drug tests can be ordered at other times, including when a commander believes a service member is using drugs or after a safety issue or accident.
• Athletic testing: Drug testing may also be required for professional athletes. The U.S. Anti-Doping Agency prohibits cannabinoids for competing athletes, regardless of the legality of marijuana in the location of the competition.
• Legal and forensic testing: Testing for marijuana and other drugs may be conducted in a court case or investigation. For example, drug testing may provide evidence of a crime such as child abuse or endangerment.

Marijuana testing detects evidence of marijuna use, not current intoxication or addiction. Marijuana can be detected for a period of days, weeks, or months after use. The length of this detection window depends on the amount and frequency of marijuna used as well as the sample type:

What does the test measure?

Drug testing for marijuana measures cannabinoids or cannabinoid metabolites in a sample of a person’s blood, hair, saliva, or urine. Metabolites are substances created while the body is breaking down a drug. Marijuana produces over 100 cannabinoids, but only a few cannabinoids and their metabolites are measured in marijuana testing.

Marijuana tests usually measure delta-9-THC, the primary psychoactive cannabinoid in marijuana, and/or its metabolites. Other cannabinoids, including cannabidiol (CBD), are less frequently included in marijuana testing.

Synthetic cannabinoids are man-made chemicals, produced and sold as an alternative to marijuana. While many users believe that synthetic cannabinoids are safe, these products may cause severe illness or even death. Initial urine drug screening tests do not detect synthetic cannabinoids.

When should I get a marijuana test?

Marijuana testing may be required during pre-employment testing and as a part of drug screening ordered by courts and other organizations.

Many federal employees are required to have regular drug testing as part of a drug-free workplace policy. Drug-free workplace programs are implemented in a variety of federal industries, including transportation and national security. Law enforcement officers and emergency service providers may also be required to undergo drug testing as part of a drug-free workplace program.

Drug testing requirements are impacted by federal, state and local laws. Although over half of states have legalized medical or recreational marijuana use, employers and other organizations may still penalize individuals for using marijuana. Marijuana remains illegal under federal law.

How to get tested

Marijuana testing can be performed in a medical facility or laboratory. Samples for testing can also be obtained on-site at a workplace.

Marijuana tests may be ordered by a doctor or administrator of a program that requires drug testing. Tests may also be purchased over-the-counter and conducted at home or by sending samples to testing facilities through the mail.

Can I take the test at home?

At-home drug tests are available to screen for marijuana use. At-home marijuana testing may be conducted on samples of hair, saliva, or urine. Urine and saliva drug testing may be completed in the home, while hair follicle drug testing is collected at home and mailed to a laboratory for analysis.

Testing for marijuana use at home is a form of initial drug screening and positive results require confirmation testing. An at-home drug test can be used for an initial test, while confirmation testing requires a sample to be sent to or collected by a laboratory. An at-home marijuana test is not a substitute for drug testing overseen by a health care professional.

How much does the test cost?

Depending on the setting in which marijuana testing takes place, the cost of this test may be paid for by a patient’s employer or the organization requiring the test. Marijuana testing may also be covered by a person’s health insurance when ordered by a doctor. For questions about the costs of marijuana testing, patients should talk to their doctor or an administrator in the program requiring drug testing.

At-home marijuana test kits may be purchased alone or as part of a larger drug panel with costs starting around $6.

Initial testing for drug use is most often performed on urine and requires a clean catch urine sample. Clean catch describes a method for collecting urine that prevents germs from contaminating the urine sample. For laboratory-based testing, a clean catch urine sample is collected in a laboratory, medical facility, or other testing site.

Blood samples used for drug testing are drawn from a vein in the patient’s arm. Hair samples are typically obtained from a person’s scalp.

At-home marijuana testing instructs users on collecting a sample of hair, saliva, or urine using instructions provided in the test kit.

Before the test

Before a drug test, patients should discuss testing procedures with their doctor or staff at the testing location. Procedures for collecting urine vary based on the reason for testing and the requirements of the test site.

In some cases, collection of a urine sample may be monitored or directly observed by a medical technician or trained staff member. Monitoring the collection of a urine sample involves having a trained professional check the restroom before the patient collects their sample. Direct observation is a more invasive requirement, involving a professional watching a person during sample collection. Monitoring and direct observation ensure that a patient does not tamper with the urine sample.

As it’s more difficult to tamper with samples of blood, saliva, or hair, there may be no special preparations necessary for these types of drug tests. It’s important for patients to tell their doctor if they are taking any prescription medicines, over-the-counter medications, or supplements.

When using an at-home test kit, make sure to read any instructions provided and prepare sample collection materials before obtaining a sample.

During the test

Prior to taking a clean catch urine test, patients are instructed to wash their hands and clean their genitals with a wipe or pad provided by the staff member. Patients then begin by urinating into the toilet before moving the collection container into the urine stream. Once the collection container is filled to the appropriate level, it is moved out of the urine stream and patients finish urinating into the toilet

Collecting blood for a drug test involves having blood drawn from a vein in the arm by a health care provider. For a drug test that requires a sample of hair, a small amount of hair is cut, usually from the scalp. If a person doesn’t have hair that can be collected from their scalp, hair from another part of the body may be collected instead.

Drug testing is usually painless, although patients may experience slight discomfort during a blood draw. Samples required for drug testing can usually be obtained in less than 5 minutes.

At-home marijuana tests require a sample of hair, saliva, or urine. Collecting these samples is performed in the same way as laboratory-based testing. Many at-home urine tests allow users to complete the test after collecting the urine sample. These test kits include a testing device such as a test strip that is immersed in the urine sample. Test devices and instructions vary, so it’s important to carefully conduct the test according to instructions provided in the test kit.

After the test

After a urine sample is collected, patients seal the sample container and return it to the health care provider for testing. There are no restrictions on activity after a marijuana test.

Receiving test results

Results from a marijuana test are often available within a few hours to a few business days. Depending on the reason for testing, patients may learn about their test results through their doctor, the testing site, or an administrator of the organization requiring testing. Test reports may also be sent electronically or in the mail.

Results of at-home urine tests are typically available within several minutes of conducting the test.

Interpreting test results

An initial marijuana urine test report is qualitative, meaning that it may only show a positive or negative result and not additional information about the type and level of specific cannabinoids.

Confirmatory testing uses a more specific test method and provides information about specific cannabinoids or metabolites measured, the level of these substances detected in the sample, as well as the laboratory’s reference range.

Reference ranges for marijuana testing are not universal and depend on the laboratory or agency conducting the test. In federal drug-free workplace programs, the cutoff for an initial test of marijuana metabolites is 50 ng/mL, while the cutoff for confirmatory testing is 15 ng/mL.

Testing negative on a marijuana test indicates that the cannabinoids or metabolites measured were not found in the test sample. This may be because the patient hasn’t used marijuana, the marijuana use was outside of the detection window, or that the level of this drug was below the cutoff level for a positive test result.

A positive marijuana test indicates that cannabinoids or metabolites were detected in the test sample. A positive drug test result requires additional confirmation testing conducted in a laboratory.

Some patients may be concerned about the possibility of a positive marijuana test result due to passive or secondhand exposure to mariuana smoke. Research suggests that testing positive after secondhand exposure to marijuana smoke is unlikely as metabolite levels in the body aren’t sufficient to be detected in most drug tests.

Are test results accurate?

Although no test is perfect, mariuana tests are highly accurate in detecting evidence of marijuana use. False positive results on marijuana tests are rare.

In order to reduce the risk of inaccurate test results, professionals take special precautions during sample collection, transportation, and testing. Clean catch urine samples reduce the risk of contaminating urine with germs, and transporting of test samples is carefully documented through a process called chain of custody.

When reviewing test results, patients can ask their doctor or the test administrator about the laboratory that conducted the test, the reference range usedDo I need follow-up tests?, and the reliability of marijuana testing.

Do I need follow-up tests?

Positive results on an initial test for marijuana require an additional confirmation test. Confirmation testing is especially important when a positive result on a marijuana test has implications for employment, legal issues, or medical treatment decisions.

If a patient tests positive on a marijuana test, their doctor may also suggest an evaluation for cannabis use disorder. Cannabis use disorder, also called a cannabis addiction, is seen in around 10% of people who use mariauna consistently and up to 50% of daily users. An evaluation for cannabis use disorder involves a series of questions to determine patterns in a patient’s marijuana use.

Questions for your doctor about test results

Drug testing can be a stressful process. Patients may find it helpful to ask their doctor questions about marijuana test results. Helpful questions may include:

• What is my test result?
• Will a follow-up confirmation test be required based on my result?
• Who will have access to my test result or medical record?

• 10-Panel Drug Test
• Ethanol

The resources below provide additional information about marijuana and drug testing:

• National Institute on Drug Abuse: Marijuana
• National Library of Medicine: Marijuana
• National Center for Complementary and Integrative Health: Marijuana and Cannabi…
• U.S. Food and Drug Administration: FDA and Marijuana
• CDC: Marijuana and Public Health
• National Institute on Drug Abuse: What are synthetic cannabinoids?

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