Marijuana drug testing guidelines

Published Jan 29, 2019 02:26 p.m. ET

Need to take a urine test for work? Worried it could be a possibility in the future? Maybe you’re just wondering how long it will take for THC to leave your system. No matter what brought you here, these guidelines will tell you everything you need to know about the three most commonly used drug testing methods.

What are the three most commonly used drug tests?

There are currently several different kinds of testing used. The most common being urine, hair, and blood. Each method has its period in which it can reliably detect THC. THC, also known as delta-9-tetrahydrocannabinol, is the main component that these three tests seek out. It is also the active chemical in cannabis that gives you the feelings and or effects sought after by most cannabis users. Here we will break down how long it takes before the THC can no longer be detected.

Urine test

This test is very accurate. When you take a urine screening test at a doctor’s office, this type of test generally uses two-part screening meaning they test the same sample for THC twice, making it much more reliable than any urine test that is administered at home. A urine test will screen for any THC or THC related chemicals called metabolites. THC in urine will show positive if the test detects any more than 50 nanograms of THC per ml. While a urine test is incapable of giving an exact time or day that you last consumed cannabis, it can detect use up to four weeks in heavy users and close to ten days in occasional users.

Hair Test


The hair test is the least specific when attempting to determine a person's last time of use. A screening for cannabis using hairis done by removing 1-3 strands of hair approximately one inch from the base and can positively detect the use of marijuanafor up to 120 days.

Blood test

Blood testing is always done by a doctor in an office setting. This kind of test has the drawback of an incredibly short window that it is considered reliable. Typically, a blood test can detect THC for only one or two days. There are however many cases where THC could still be found as much as many as 25 days after last use in chronic users.

How to get weed out of your system

Now that we know what the numbers are, you might be wondering how to cleanse your system, is there such a thing as a weed cleanse?Is there a THC flush, or a drink that works? Typically, the answer is no. Though there is a vast market out there full of drinks and powders claiming to promise success, the majority have shown to have little to no effect on how much time THC takes to leave the system completely. So how do you cleanse your system? The most effective way to cleanse your system is to eat healthily, drink plenty of water, and exercise. All these things along while abstaining from use will help your body to naturally process the metabolites faster giving you the best chance at passing your next test.


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