Fraser Horton
Fraser Horton
Last Updated on December 29, 2020

As marijuana use increases around the world, so does workplace drug testing. More and more employers require their employees to take mandatory drug tests to check for the presence of cannabis and other drugs in their system. 

Because of this you may ask yourself, can you help your body flush out the cannabis metabolites faster in order to pass your test? Below, we’ll go into detail as to how long marijuana stays in your system, what are the detection times for certain tests, as well as how to flush out weed from the urine faster.

How Do Drug Tests Detect Cannabis?

The cannabinoids found in THC like delta9-tetrahydrocannabinol (THC) and cannabidiol (CBD) are lipophilic, meaning when weed is consumed, the cannabinoids are stored in the fat cells of the body. Once your body metabolizes THC, the byproduct – 11-nor-9-carboxy-THC or THC-COOH – is stored in body fat. This metabolite is the evidence that gets picked up in drug tests (urine tests). 

Different testing methods have different detection times, but some factors can affect how quickly your body metabolises THC like:

  • The dosage and frequency of use (chronic users have longer detection periods);
  • Your physical activity, body mass index (BMI), metabolic rate, and weight (since females generally have more body fat than males, they may metabolise cannabinoids more slowly);
  • The type of drug test and how sensitive it is (the cutoff of the test, or the amount of THC it’s able to detect);
  • How long has it been since your last use;
  • Other underlying medical conditions.

Detection Times for Different Drug Tests

As we previously said, the length of time THC is detectable in the body depends on your biology and habits, as well as how sensitive the test is and what the cutoff levels are. We’ve listed the most common testing methods as well as a detection window for each test depending on how frequent the use is. 

The drug tests that are available on the market today include:

  • Urine tests;     
  • Blood tests;
  • Saliva tests;
  • Hair follicle tests.

Urine Testing (Urinalysis)

While different sources have different guidelines when it comes to urine testing for cannabis use, there are some approximated guidelines, and the urine sample can show different results depending on how often you use cannabis. (Kouri et al, 2000, Moeller et al, 2017, Sharma et al, 2012)

When testing for drug use, and especially cannabis use, the standard for urinalysis is the 50ng/ml cutoff (nanograms per milliliter). A study has also been done on heavy marijuana users that found traces of the metabolite delta 1-THC when doing a urine test even four weeks after use because this metabolite has an unusually long half-life.

The detection times of cannabinoids and cannabinoid metabolites in urine are the following:

  • Occasional user (from one to three times per week): 3 days;
  • Moderate user (about four times per week): 5-7 days;
  • Chronic user (uses daily): 10-15 days;
  • Heavy chronic user (uses multiple times per day): 30 or more days.

Saliva Testing

Oral fluid testing is a non invasive method of drug testing when you compare it to blood tests, and it’s more expensive than a urinalysis. It’s done by testing a swab of saliva and checking if the levels of THC are normal or not. Heavy chronic users can have a longer detection window of up to 29 days, while occasional users will test positive from 1-3 days after consuming marijuana, according to a study done by the National Institute of Baltimore in 2014.

Blood Testing

Blood tests are more expensive than other drug tests like urinalysis, and they’re also more invasive. While urine tests check for cannabinoid metabolites, blood tests look for the presence of THC, and they’re ideal for detecting recent drug use. According to an article by the Addiction Center, THC stays in the blood anywhere between 4 and 24 hours, while chronic users can test positive for up to a week.

Hair Testing

The hair follicle drug test is done by taking around 100 hairs from the crown of the head, and using dye or other hair products will have no effect on the test.

When weed is consumed, THC gets to the hair follicles through the small blood vessels, and it can be detected when doing a hair test for up to 90 days depending on how frequently the user consumed cannabis, according to a 2015 study. Because it takes seven days for the metabolites to enter the hair follicle, this method can’t be used to test for current impairment.

How to Eliminate THC Metabolites in Urine?

There’s no one-answer-fits-all when it comes to the question about eliminating THC metabolites from the urine. When it comes to drug screening, cannabis users are willing to try anything from running to taking homemade detox drinks from cranberry juice, in order to avoid positive drug test results. (Wong et al, 2013)

Detoxification can be longer in regular users and heavy users since their body stores bigger amounts of THC, compared to occasional users.

The first thing you need to do before your mandatory drug test is to stop consuming cannabis altogether, so you’re more likely to pass. Next, you should drink plenty of water in order to flush the weed out faster, but don’t overdo it, because you risk the sample looking too diluted and suspicious to the people testing you. To avoid this, some people take a B12 or B2 supplement that can darken the urine and mask their dilution attempt.

Detox Products and Home Test Kits

If you’re thinking about taking different measures apart from drinking water and exercising, you must have heard about THC detox kits. Some of them include fruit pectin which supposedly stops THC metabolites from passing in the urine and forces them out via the feces. 

Other ingredients that act as diuretics and speed up the metabolism include red clover and yellow dock root.

Detox drinks, on the other hand, work by expelling or masking the presence of THC and metabolites like THC-COOH from the urine, and are used by a lot of people who are trying to pass a cannabis drug test.

Apart from the metabolites, drug tests look at the amount of creatinine in the urine, so you might want to take it as a supplement if you’re planning on taking cleanses, teas, or niacin that lower THC through their diuretic properties.

In order to double-check if you’re good to go for your drug test at work, you may want to try a home test kit. This type of drug screening is similar to the ones used while testing in the workplace and it uses a method called immunoassay (IA) panel. The panel includes the SAMHSA-5 standard established by the federal Substance Abuse and Mental Health Services Administration. 

Final Thoughts on Detoxing Weed From Your System

Substance abuse is a big problem at the workplace, so mandatory drug testing is a common occurrence nowadays. So if you have an upcoming drug test, there’s no fool-proof method of eliminating THC out of your system quickly, although the methods mentioned here might help you detox faster and get a negative result. Since the most commonly done test is the urine test, drug tests look for THC metabolites like THC-COOH in the urine. 

In order to increase your chances of getting negative test results, you must stop using weed immediately in the period leading up to the test. Next, you might want to drink a lot of water in order to speed up the excretion of THC, but don’t drink too much or your sample might look suspicious. You could also try using different detox drinks and exercise more so you’ll be able to pass the test.

Additional Sources

Karen E. Moeller, Julie C. Kissack, Rabia S. Atayee, Kelly C. Lee, March 18, 2017, Clinical Interpretation of Urine Drug Tests, Mayo Clinic DOI:https://doi.org/10.1016/j.mayocp.2016.12.007

Kouri, E. M., & Pope, H. G., Jr (2000). Abstinence symptoms during withdrawal from chronic marijuana use. Experimental and clinical psychopharmacology, 8(4), 483–492. https://doi.org/10.1037//1064-1297.8.4.483

Sharma, P., Murthy, P., & Bharath, M. M. (2012). Chemistry, metabolism, and toxicology of cannabis: clinical implications. Iranian journal of psychiatry, 7(4), 149–156. 

Wong, A., Montebello, M. E., Norberg, M. M., Rooney, K., Lintzeris, N., Bruno, R., Booth, J., Arnold, J. C., & McGregor, I. S. (2013). Exercise increases plasma THC concentrations in regular cannabis users. Drug and alcohol dependence, 133(2), 763–767. https://doi.org/10.1016/j.drugalcdep.2013.07.031

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