How Long Weed Stays In Your Body

Allie Adams
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Whether a bus driver, a nurse, an athlete, or mandated for court-ordered purposes, there are many reasons an individual would need to take a drug test to know whether or not cannabis, or its main component, THC, is present in their system. But with so many conflicting reports, it’s hard to know exactly how long weed stays in your system, and how long it will take to pass a drug test and get a negative result.   Buckle up, because we’re going to dive into the nitty-gritty of all the factors that contribute to how long cannabis stays in your system. And with so many different testing methods, we’ll also take a look at how your usage levels and other factors affect specific testing results.   Almost half of all adults in the USA say they have tried cannabis at least once, and nearly 30% consume on a regular basis, according to a Gallup poll Even with such widespread use, many employers do not allow their employees to test positive for weed, especially in industries such as transportation–think bus drivers and airline pilots, and healthcare–think nurses and hospital workers. Many court-ordered drug treatment programs also regularly test for weed, in addition to other substances, so knowing how long THC stays in your system is important if you choose to consume.

What is THC?

TCH weed
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THC is the abbreviation for delta-9-tetrahydrocannabinol, and is one of the main psychoactive compounds found in theCannabis Sativa L. plant. While THC is responsible for the intoxicating effects of cannabis, it is not the compound that urine drug tests, the most common test, actually detect. It is important to note that urine tests “detect the non-psychoactive marijuana metabolite THC-COOH, which can linger in the body for days and weeks with no impairing effects. Because of THC-COOH’s unusually long elimination time, urine tests are more sensitive to marijuana than other commonly used drugs”, according to the California NORML Guide to Drug Testing   This distinction is an important one: just because THC gets you high doesn’t mean it is the compound that stays in your system.

How Long Does Cannabis Stay in Your System?

It’s hard to say exactly how long weed stays in your system on an individual level due to a variety of factors such as frequency of use, body mass index, physical activity level, and personal body physiology. However, there are some general guidelines for each type of test. Not surprisingly, frequency of use was the biggest determining factor in how long weed actually stays in your system, with some reports stating that weed can be detected for up to 100 days in the urine test of a heavy user. Below is a chart to quantify some of these guidelines: 

How Long is Cannabis Detectable in a Drug Test?


How the Different Tests Compare?


Cannabis makes its way to the hair follicle via the bloodstream, sweat and sebum. While detectable for 90+ days, a hair follicle test is considered one of the least dependable forms of cannabis drug testing because the presence of surface secondhand smoke can result in a false positive.


The saliva test is popular in roadside testing due to the short window of detection (0-24 hours). According to Healthline , “Weed can enter the saliva through smoking and exposure to smoke. However, its metabolites are only present in saliva when weed has been smoked or ingested.” The test is administered via an oral swab on the inside of the mouth.


Because cannabis retains the highest concentration for the longest period of time in urine, a urine test is the most widespread choice of cannabis drug test, and is considered the most accurate for detecting long-term use. Urine tests can be administered in a lab or an at-home kit that is sent to a lab for results.


Unlike urine tests which detect THC-COOH as mentioned prior, a blood test detects THC. A study by Therapeutic Drug Monitoring suggests that in some chronic users, THC can still be detected in your blood for up to 25 days after your last use. A blood test is administered in a lab via a blood sample.

3 Key Factors That Affect How Long Weed Stays in Your System?

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As we talked about above, there are many different physiological attributes that affect how long cannabis is present in the body. Because THC and other compounds in weed bind to fat cells, body mass index and weight are the two cornerstones of cannabis storage timeframe in the body. Those, however, are not the only factors that contribute to the length of time cannabis remains detectable in the body

1. Body Mass Index

Simply put, the more fat you have, the easier it is for cannabis to be stored in your body and the longer it will take to clear. This isn’t to say that someone with a higher BMI and fast metabolism can’t clear cannabis from their body as someone with a lower BMI, but it’s a good measuring rod.

2. Metabolism

The faster your metabolism, which is simply the chemical changes that take place within the body, the faster cannabis can clear your system. The speed of metabolism is affected by age, weight, and genetics among other things.

3. Frequency and Potency

The more often you use cannabis, the longer it takes to clear the body. Additionally, the stronger the weed you are consuming, the longer it takes to clear the body. It is thought, although not proven, that consuming high levels of THC via ingestion takes longer to exit the body than by simply smoking.

While testing methods differ and many factors can affect the amount of time THC or any cannabis compound stays in your system, it’s important to take note of personal body physiology and allow enough time to completely clear weed from your system.

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