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

What Is THC ?

THC, or delta-9-tetrahydrocannabinol, 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.

Effects of THC

The potential effects and risks of marijuana and THC use include: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?

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 Weed 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 Weed Stay in Your Hair?

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

How Long Does Weed Stay in Your Blood?

The window of detection for weed in a person’s blood may be up to 12 hours. Marijuana remains in the bloodstream for a short amount of time, so blood tests for marijuana detection aren’t typically used.

That’s because while the THC reaches the bloodstream quickly (within minutes of inhalation), the THC concentrations in the bloodstream rapidly decrease roughly 3-4 hours after ingestion.¹²

Factors that Impact Weed Detection Time

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 THC 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 Weed Smoke 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

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 and risk of experiencing marijuana withdrawal if use is suddenly stopped.^9,10

If you’re concerned about an inability to quit using marijuana, we can help. Recovery First offers addiction treatment in South Florida that incorporates various 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 levels of addiction treatment  designed to meet you where you are, from inpatient rehab to intensive outpatient therapy.

Call us at to learn more about our Florida substance abuse programs, ways to pay for rehab, and how we can help you find freedom from addiction today.