How Long Does Marijuana Stay in Your System?

  • The marijuana detection window varies between different parts of your body
  • Usage frequency, dosage, BMI, and other factors affect how long marijuana stays in your system
  • A medical marijuana card can’t necessarily safeguard you during workplace testing

Does marijuana stay in your system for only 3 days? Why do some people say it’s detectable even 30 days after you’ve last taken this popular, but regulated product? Both of these timelines are actually correct. Multiple factors determine the exact period of time you’ll have to wait before drug testing won’t pick up any THC traces.

For any person enjoying marijuana—occasionally or regularly—this presents a problem if you may be given a blood or urine test for situations such as a job application. To help you navigate these tricky situations, we’ve compiled a clear but concise summary of the topic.

How Long Does Weed Stay in Your System?

Compounds of marijuana can be present in various parts of your body. This is why there are multiple tests created to determine whether someone recently used marijuana.

For each part of the body as well as the different bodily fluids, there’s a different length of time that these compounds will remain there before leaving your body completely. Therefore, the type of test that is done will affect how long after marijuana usage you’ll still have positive tests.

How Long Does Marijuana Stay in Urine?

Urine testing is a popular method of testing for marijuana.

THC (tetrahydrocannabinol) or its metabolites like THC-COOH (11-Nor-9-carboxy-THC) will be excreted into your urine and can be picked up in a test. However, the timeline of how long it will be present varies between users, with the frequency of use being a determining factor.

  • If you’re an infrequent user, usually a urine test will detect the compounds a maximum of 5 days after the last usage.
  • Heavy users have a detection window of 15 days, but chronic users can test positive for up to 30 days. The 30-day timeline also applies to users with high percentages of body fat.

Note that some urine tests are designed to pick up tetrahydrocannabinol THC while others look for the metabolites of THC. The type of urine test can affect the outcome because metabolites will stay in urine longer and may therefore be detected even if a THC urine test comes up clean.

How Long Does It Take for Marijuana to Leave Your Saliva?

A saliva test looks for THC, not its metabolites, which means there’s less time during which you’ll produce positive results. For this test, a swab will be used to obtain some saliva from the inside of the mouth.

As mentioned above, metabolites show presence longer than THC, the parent drug. However, the detectable particles are usually not present for longer than 72 hours.

How Long Does Marijuana Stay in Your Blood?

Blood tests are invasive and not that popular for marijuana testing for multiple reasons, since the compounds leave the blood sooner compared to fluids like urine. In addition, a blood test may show the presence of the substance, but not necessarily how much of it is present in someone’s system. Usually, these tests are only used as part of accident investigations, immediately after an incident.

Although the blood renewal system of an individual will play a role, in general, a person using marijuana occasionally will have positive blood during the 24 hours after consumption. But note, some people can have negative tests in as little as 12 hours. If you’re a frequent user it will take around 7 days for your blood to seem marijuana-free.

 How Long Does Marijuana Stay in Your Hair?

Hair follicles testing is very different from the fluids above. A test may be able to pick up traces of marijuana, in the form of metabolites, as long as 90 days after someone has last consumed marijuana.

A testing facility may need at least 1.5 inches of hair, since a shorter strand will shorten the detection period. The facility will use a piece of hair closest to the scalp.

Do note that with less frequent marijuana users, tests may not be as accurate and effective.

How Long Does Marijuana Stay in Your System

What Factors Affect How Long Marijuana Stays in Your System?

The answer to a question such as ‘how long does marijuana stay in your system’ can’t have a simple answer. Too many factors are at play and to help understand some of their influence, here’s a quick reference guide of multiple factors that could impact your test.


Consider how much marijuana you consume but also the potency and type of weed. This affects dosage, or rather, the amount of THC your body contains. The more there is, the longer and harder your body has to work to first break it down and then eradicate or expel it.

Consumption Method/Product Type

The way you enjoy consuming marijuana can have an indirect impact on the amount of time it stays detectable. With some methods, you may not realize what a large dosage of THC you’ve taken. For example, you’ll wait a while to feel any effect when you enjoy edibles, but smoking has a very early onset. This could lead to you eating more, thinking you haven’t taken enough, and elevating THC levels drastically.

Frequency Of Use

Because of cumulative effects, regular users may have a longer detection window than first-time or occasional users. In general, a regular user is seen as someone who uses marijuana more or less daily.


For users that have high metabolisms the detection window will be shorter than for someone whose body metabolizes slowly. This is because metabolism affects how quickly any substance, including THC is broken down and eliminated.

Body Fat

THC is a fat-soluble compound. Some of it can bind to fat molecules and stay in your body for a longer time than other particles that are already broken down and expelled from your system. Therefore, your body mass index BMI reading can give you an indication of whether you’ll have shorter or longer detection windows than others with similar usage levels.

Hydration Rate

Your body’s water percentage can affect how long marijuana stays in your system because it affects processes in your body. For example, your organs function better at a high hydration level, so you could excrete marijuana compounds faster if you hydrate more.

Exercises: Can You Sweat Out THC?

Your level of exercise can affect how long marijuana is detectable but to a minor degree. With excessive exercise, you may sweat out some THC. However, its metabolites are likely to stay behind and if a drug test is focused on them rather than THC, technically there will still be marijuana in your body.

How Long Does Marijuana Stay in Your Blood

What Tests Are There to Detect Marijuana?

Over the years, multiple tests using the fluids and hair discussed above have been developed to test for marijuana. Well-known tests include:

  • Fluid tests, using urine blood, or saliva
  • Duquenois-Levine reagent test which changes color
  • Azo dyes that are sensitive to some cannabinoids
  • Neurological testing which measures the frequency of alpha waves

These tests can be for medical or athletic screening but are also used for employment testing and to test military personnel. It can be part of legal and forensic investigations too.

What Dosage of THC Is Detectable?

The dosage of THC that a test can detect depends on the test. For example, a saliva test can still pick up Delta 9 THC at a ratio of 0.5ng/mL while a cannabis hair test can detect at 1pg/mg.

Will Medical Marijuana Make Me Fail a Test?

Like any other cannabis product, medical marijuana contains THC and this can be detected in a drug test. Therefore, you may fail a test by getting a positive marijuana reading. However, whether someone like an employer could discriminate against or fire an employee because of the outcome depends on state laws and company policies.

With marijuana use still being a controversial topic in many countries, drug tests that also check for marijuana will still be around for a long time. Luckily, with knowledge comes power. If you’re more aware of facts like how long it takes for marijuana to leave your system completely, you can still enjoy this beneficial natural substance without putting your career or other life opportunities at risk.

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Heather Wilson is a passionate cannabis enthusiast who has dedicated over four years of her life to working as a budtender. With a deep understanding of the difference between marijuana strains, cannabinoids, terpenes, and their effects, she has helped countless customers find the perfect product for their needs.

In addition to her work as a budtender, Heather is also an enthusiastic cook who loves to try new recipes incorporating cannabis. Whether she's whipping up a batch of infused cookies or cooking a delicious meal with cannabis-infused oil, Heather is always eager to explore the culinary possibilities of this versatile plant.

For Heather, cannabis is more than just a recreational substance. She uses it for her health and is an advocate for safe and responsible use. With a strong desire to spread awareness about the benefits of cannabis and fight the stigma that still surrounds marijuana, Heather is a true champion of this misunderstood plant.

Through her work and cooking, Heather is helping to change the conversation around marijuana and show the world that this plant has a lot to offer, both medically and recreationally. Heather joined with Brian to found Concept420 in 2022.

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