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Monday June 26, 2017

By Michael Walters

Image of a cannabis joint smoking in a turquoise and yellow ash tray Health/Science

Whether you fear an imminent drug test or simply want to know more about marijuana’s effect on your body, you’ve likely wondered how long cannabis stays in your system. Not only will this information help you avoid the negative consequences of testing positive, but it also helps you decide whether you personally want to use cannabis. So, how long does cannabis remain in the body?

The Short Answer

For most people, cannabis stays in the body in large enough quantities to be detected for no more than a month, and often as little as 10 days. Specific detection times, however, vary based on how long you have used the drug and what type of test you take.

The most common detection methods include:

  • Urine Tests

    If you've only used cannabis once, a urine test can detect it within 7 days. If you use it regularly, detection times can range from a week to 100 days, though they usually fall under 30.

  • Blood Tests

    Of more limited duration than urine tests, blood exams can detect cannabis in repeat consumers between 2 and 7 days after the last time they used it. If you have only used it once, these tests typically work for 24 hours.

  • Hair Tests

    This method is of limited value on single users, but for repeat users, it can detect cannabis for months afterwards – sometimes years for heavy consumers.

  • Saliva Tests

    These exams have not yet been shown to work, whether for repeat or single users.

Different methods have different detection times because they don't search for the same thing. Urine tests, for example, detect THC-COOH, which is not psychoactive, while blood tests look for the psychoactive version of THC. This makes blood tests better for measuring actual impairment.

While these are the average detection times, they may not be accurate for you as an individual. Heavy users, for example, might take much longer for THC to leave their system. Because of this, it is important to consider the following information.

Urinalysis is the most common method of drug testing.

Factors for Finding Cannabis

The length of time cannabis stays in your system and your likelihood of testing positive both depend on a wide variety of factors. These include:

  • Body Fat Content

    Cannabinoids, or chemical compounds responsible for the effect of cannabis on the brain, store themselves in fat cells. Thus, the higher a percentage of body fat you have, the longer it will be in your body. In general, this means that people with higher body mass indices (BMIs) will have cannabis in their system for longer, though BMI is not perfectly correlated with body fat content.

  • Exercise

    While exercising does not increase the total amount of time that cannabis stays in your system, it may increase your likelihood of testing positive on a drug exam. When you exercise, your body burns fat, releasing chemicals stored in that fat into the bloodstream. Thus if you exercise shortly before taking a drug test, it is more likely to find the substance. However, exercising weeks before an exam is recommended because it will burn fat cells containing cannabinoids.

  • Hydration

    If you are dehydrated when you take a drug test, there will be less water in your urine or blood, meaning that cannabinoids will make up a higher percentage of the sample. As with exercise, this technically does not make it stay in your system longer, but it can cause you to test positive at a later date than you otherwise would.

  • Drug Strength

    Different varieties of cannabis have different levels of strength. The stronger it is, the higher a concentration of THC it has. This can leave more cannabinoids in your body, which may take longer to eliminate.

  • Metabolism

    An individual’s metabolism affects the rate at which their body eliminates cannabis. It also affects the amount of body fat they have, further influencing cannabinoid detection.

  • Other Factors

    Height, age, gender, and the method you used to ingest cannabis all affect how long it can be detected in your system.

Based on this information, many people think they can find ways to lower their probability of testing positive for cannabis use. While it is true that lowering your amount of body fat and staying fully hydrated can improve your odds, quick fixes have a poor track record of helping people pass drug tests.

Many people, for example, try to flush out their systems with water immediately prior to being tested; this has limited effectiveness at best, especially on short notice. The most reliable way to avoid positive results is to not use cannabis if you expect to be tested within the next month, and to moderate the strength of the drug when you do use it.


Michael Walters Michael Walters

After graduating from the University of Wisconsin-La Crosse with a degree in Writing and Rhetoric, Michael started his journey in the cannabis industry managing content, communications, and technical writing for one of Colorado's largest dispensary chains. In 2016, Michael pivoted to the ancillary sector to become PotGuide's Content Manager and was responsible for overseeing all of PotGuide’s editorial endeavors and content marketing strategies. Now, Michael is PotGuide's Director of Content & Marketing, focusing his efforts toward new educational content and exciting media endeavors.

With a life-long passion for cannabis knowledge and education, Michael devoted himself to becoming a subject matter expert on marijuana at an early age. Now, Michael has worked in the marijuana industry for over four years helping break down negative stigma and promoting safe cannabis practices. An avid consumer himself, Michael has worked tirelessly to improve content marketing strategies for cannabis businesses and is devoted to creating meaningful content that is useful to a wide variety of marijuana consumers. Follow Michael on LinkedIn and Instagram for updates and insights.

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