About the 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 also be ordered 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.
Testing for marijuana, especially in urine, detects evidence of 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 marijuana used as well as the sample type:
Testing SampleEstimated Detection Window
| MARIJUANA USE DETECTION WINDOWS | |
|---|---|
| Blood | Up to 7 days |
| Hair | Up to 90 days |
| Saliva | Up to 24 hours |
| Urine | Up to 3 days (up to 6 weeks in heavy users) |
What does the test measure?
Drug testing for marijuana measures cannabinoids or cannabinoid metabolites in a sample of blood, hair, saliva, or urine. Metabolites are substances created while the body is breaking down a drug. Marijuana produces over 100 different 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.
When should I get THC testing?
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. These 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, which remains illegal under federal law.
Finding a Marijuana Test
How can I get a Marijuana test?
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, 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 may be paid for by your employer or the organization requiring the test. Marijuana testing may also be covered by your health insurance when ordered by a doctor. For questions about the costs of marijuana testing, talk to your doctor or an administrator in the program requiring drug testing.
Taking a Marijuana Test
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 your arm. Hair samples are typically obtained from your scalp.
At-home marijuana testing instructs you on how to collect a sample of hair, saliva, or urine using instructions provided in the test kit.
Before the test
Before a drug test, discuss testing procedures with your 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 you collect your sample.
Direct observation is a more invasive requirement, involving a professional watching during sample collection. Monitoring and direct observation ensure that you don’t 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 you to tell your doctor if you 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, you’ll be instructed to wash your hands and clean your genitals with a wipe or pad provided by the staff member. You’ll then need to begin 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 you can 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 you don’t have hair that can be collected from your scalp, hair from another part of the body may be collected instead.
Drug testing is usually painless, although you may experience slight discomfort during a blood draw. Samples required for drug testing can usually be obtained in less than five 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 you to complete the test after collecting the urine sample. These test kits include a 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, you seal the sample container and return it to the health care provider for testing. There are no restrictions on activity after a marijuana test.
Marijuana Test Results
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, you may learn about your test results through your 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, and the laboratory’s reference range.
The cut-off levels for distinguishing positive from negative specimens is not universal and depends on the laboratory or agency conducting the test commonly either 20 ng/mL, 50 ng/mL, or 100 ng/mL. In federal drug-free workplace programs, the cutoff for an initial test of marijuana metabolites is 50 nanograms per milliliter (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 you haven’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. Also, a positive drug test result requires additional confirmation testing conducted in a laboratory.
You may be concerned about the possibility of a positive marijuana test result due to passive or secondhand exposure to marijuana 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.
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?
Additional Resources
- National Institute on Drug Abuse: Cannabis (Marijuana)
- National Library of Medicine: Marijuana
- National Center for Complementary and Integrative Health: Cannabis (Marijuana) and Cannabinoids: What You Need To Know
- U.S. Food and Drug Administration: FDA and Cannabis: Research and Drug Approval Process
- CDC: Marijuana and Public Health
- National Institute on Drug Abuse: What Are Synthetic Cannabinoids?
