How Long Does Marijuana Stay in Your System?

With changing marijuana laws in numerous states, use of the drug is growing. According to the Substance Abuse and Mental Health Services 2019 National Survey on Drug Use and Health, use of marijuana by individuals in the U.S. aged 12 years old or older grew from approximately 11% (nearly 26 million) in 2002 to 17.5% in 2019 (more than 48 million).1

Increasingly relaxed societal views on the harms of marijuana have led to more and more people trying the substance. The same 2019 survey showed that past-year initiation of marijuana use among adults age 26 and older grew significantly from 90,000 in 2002 to 887,000 in 2019.1

However, even with increasing acceptance of weed, it’s not legal everywhere, and even in places where it is, drug tests may be required for employment or other reasons. This leaves many people wondering just how long marijuana stays in their system. While there are estimates, there is no exact answer to how long weed will show up on a urine or other test. Marijuana’s drug’s detectability is impacted by many factors such as the frequency of use and the dose.2,3

The only way to ensure you pass a drug test for marijuana is to not use marijuana.

What Is THC?

THC, or delta-9tetrahydrocannabinol, is the primary psychoactive component of marijuana.4 THC is largely responsible for the euphoric high associated with marijuana, but its use can result in other short-term effects, including:5

  • Altered visual perception.
  • Changes in sensing time.
  • Mood changes.
  • Cognitive impairment.
  • Memory problems.
  • Hallucinations or delusions (more likely with high-dose use).
  • Psychosis (more likely with regular use of high-potency weed).

How long Does THC Stay in Your System?

Man smoking a joint

While the immediately noticeable effects of weed tend to wear off within a matter of hours, the THC compound itself stays in the system for a significant period of time (days or weeks); both THC and its metabolites can be detected on a drug test for longer than you may think.6,7

Even if you only use marijuana occasionally, THC can remain in your system for up to 10 days. If you use marijuana regularly, THC may stay in your system for weeks or even a month. If you’re a chronic user, it may remain even longer.6

How Long Does Marijuana Stay in Your Urine?

The timelines given below are only an estimate, as different testing assays may result in variable windows of detection.

Generally, light or moderate use of marijuana could result in positive urine test results for a window of approximately 4-7 days.8 In heavier users, urine screening may detect prior cannabis use for much longer (24-27 days).2, 3

How Long Does Marijuana Stay in Your Blood or Hair?

Blood and hair tests may be able to detect marijuana use for an even longer time period. For example, a hair follicle test may be able to detect THC metabolites in a heavy user for up to 3 months.3

Factors that Impact Detection Time

Drug test for THC

The amount of time that marijuana (THC) can be detected on a drug screen is variable, meaning it is not always the same.2,3

Factors that influence how long a drug test will be able to detect the compounds in marijuana include: 2,3

  • The amount of marijuana ingested.
  • The frequency of the marijuana use (occasional or chronic use).
  • How sensitive the drug test is.
  • The type of test (urine, hair, blood).

Are False-Positive Results Possible?

A false-positive result may occur in some rare cases. For example, certain medications may show positive results. One such medication is an anti-nausea medication sometimes prescribed for patients undergoing chemotherapy, dronabinol.6

Other medicines and herbal supplements that contain cannabidiol may also give false-positive results.6

Can Secondhand Marijuana Cause a Positive Test?

Some people wonder if being exposed to secondhand marijuana smoke will result in a positive drug test. This is possible but unlikely. Certain research has shown that secondhand smoke exposure has resulted in positive tests; however, this research was conducted in unrealistic conditions. A normal exposure to secondhand marijuana smoke is not likely to produce the level of marijuana compounds in the system that would be detectable in most tests.2

Help for Marijuana Addiction

If you’re unable to control your marijuana use and find yourself in a repeating cycle of using and trying to evade drug tests, you may need help.

Society’s beliefs about marijuana are changing, and many people use under the assumption that marijuana is harmless or that marijuana addiction is not possible. However, the National Institute on Drug Abuse (NIDA) states that between 9% and 30% of people who use marijuana have some form of marijuana use disorder, which reflects an inability to control marijuana use despite the harmful consequences. Young people are particularly at-risk, according to NIDA; those who use marijuana under the age of 18 are 7 times more likely to develop a marijuana use disorder than those who begin in adulthood.5

The rising potency of marijuana may also contribute to an increased risk of addiction for users. Many products now have higher THC levels than they did in the past, and this raises both the physical and psychological dangers as well as the addiction potential.9,10

If you’re concerned about an inability to stop using marijuana, we can help. Recovery First offers behavioral therapies, such as cognitive-behavioral therapy, which have been shown to be effective in the treatment of marijuana use disorder.11 We also offer different programs designed to meet you where you are, from inpatient rehab to intensive outpatient therapy. Call us at 954-526-5776 to learn more about how we can help you find freedom from addiction.


  1. Substance Abuse and Mental Health Services Administration. (2020). Key substance use and mental health indicators in the United States: Results from the 2019 National Survey on Drug Use and Health (HHS Publication No. PEP20-07-01-001, NSDUH Series H-55). Rockville, MD: Center for Behavioral Health Statistics and Quality, Substance Abuse and Mental Health Services Administration.
  2. Miller, S. C., Fiellin, D. A., Rosenthal, R. N., & Saitz, R. (2019). The ASAM Principles of Addiction Medicine, Sixth Edition. Philadelphia: Wolters Kluwer.
  3. Taylor, M., Lees, R., Henderson, G., Lingford-Hughes, A., Macleod, J., Sullivan, J., & Hickman, M. (2017). Comparison of cannabinoids in hair with self-reported cannabis consumption in heavy, light and non-cannabis usersDrug and alcohol review36(2), 220–226. 
  4. What is Marijuana? (2020). What is Marijuana?
  5. National Institute on Drug Abuse. (2019). Marijuana DrugFacts.
  6. University of Rochester Medical Center. (n.d.). Cannabinoid Screen and Confirmation (Urine).
  7. National Institute on Drug Abuse. (2020). What are marijuana’s effects?
  9. National Institute on Drug Abuse. (2020). Is Marijuana Addictive?
  10. National Institute on Drug Abuse. (2020). Marijuana Concentrates DrugFacts.
  11. National Institute on Drug Abuse. (2020). Available Treatments for Marijuana Use Disorders.

About The Contributor

Scot Thomas, M.D.
Scot Thomas, M.D.

Senior Medical Editor, American Addiction Centers

Dr. Thomas received his medical degree from the University of California, San Diego School of Medicine. During his medical studies, Dr. Thomas saw firsthand the multitude of lives impacted by struggles with substance abuse and addiction, motivating... Read More

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