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How Long Does Weed Stay in Your System?

First things first: when we say “weed” or “marijuana” testing, what we’re actually talking about is a THC drug test (THC, of course, being the psychoactive component of marijuana that gives you that “high” feeling).

It’s not possible to answer this question with a sweeping generalization. For one thing, the amount of detectable THC in your system will depend on many factors, such as your biology, dosage, and frequency. To paint a more accurate picture, let’s have a look at how long marijuana can last in different parts of your system in the context of popular THC tests, such as:


Hair follicle tests are known for being among the most sensitive drug testing options, and for a good reason. A hair follicle drug test can detect drugs up to 90 days after use. When you use any kind of drug—marijuana included—it seeps into your bloodstream and eventually becomes a part of the cells in your hair. It usually takes about a week for the evidence of drug use to become detectable in hair follicles.

Hair follicle tests often occur in a clinical setting, but an employer may also use an at-home kit to carry out the test within the workplace. The test works by collecting and examining a number of hairs from different areas of your scalp.


A blood test for marijuana can usually detect THC for up to 1 to 2 days after use. However, this varies considerably depending on the frequency and level of drug use. If you are a heavy user of marijuana, it may be detectable in your blood for a longer period.

As THC is detectable in the bloodstream immediately after use, it is often the test of choice to use following a work accident or investigation.


The urine test is the most popular test type for THC, so how long does THC stay in urine? THC is detectable in urine testing for anywhere from 3 days to 30 days or longer. The range is wide and hard to predict because it depends heavily on how frequently a user partakes in marijuana.

If you are familiar with cannabis baking, then you are probably aware that marijuana is fat-soluble. This means that the body is very skilled at holding on to traces of THC, meaning that it can take a long time to leave your body altogether. That’s why there is such a wide date range associated with the urine test—everyone’s body is different.


The frequency of drug use will also play a big part in how long marijuana in the saliva is detectable. While occasional users seem to carry detectable levels for 1 to 3 days, heavy users may have THC detected in their saliva for as long as 30 days after use. A saliva test may also be called a “mouth swab test”.

So, how long does it take weed to leave your system? The answer to that is a big “it depends”.

How Much Weed Do You Have to Smoke to Fail a Drug Test?

Now that we know the detection windows for the most popular blood tests, it begs the question: just how much weed do you need to smoke to receive a failing grade? This question is equally difficult to answer, but there are some benchmarks to keep in mind.

For example, we know that some drug tests are sensitive enough to detect even a small amount of THC, depending on the person. Here are a few factors that will determine how detectable an individual’s level will be:


Obviously, the higher the dose of marijuana, the more likely it will be to be detected. The problem is that calculating a weed dosage is not always easy. Although we know that the average American joint contains around 0.3 grams of marijuana, this does not accurately tell us how much marijuana the average smoker will ingest, as they may be sharing the joint and therefore only ingesting a portion.

Frequency of smoking

As mentioned above, several of the commonly-used tests will detect THC use for a more extended period if the individual undergoing testing uses weed with a high frequency. For example, how long THC stays in urine will vary greatly depending on how frequently a user partakes.

Physiological properties and unique body chemistry

Studies have shown that an individual’s unique physiological attributes, such as sex, may affect how the body absorbs cannabis. Other factors such as genetics may also affect how long THC is detectable in your body.


Exercise will work more effectively for those with a higher metabolism because individuals with a higher metabolism can break down THC faster.

Can You Get THC Out Of Your System Faster?

There is no proven instant antidote for accelerating the removal of THC from your body—the best way to detoxify before a drug test is by abstaining for a prolonged period. In other words, if you don’t smoke weed, THC won’t show up on a test. Kinda obvious. However, some individuals have found the following methods helpful in breaking down THC to get it out of your system more quickly:


Some people believe that hydrating after THC use helps decrease its detection levels. However, the matter of whether or not you can “flush” out THC traces by hydrating heavily before a drug test remains scientifically controversial. There are not extensive studies on the matter.


Exercise can affect the length of time that THC is detectable. Because THC is stored in fat, burning fat through exercise may help release it from your system.

Healthy diet

Eating foods that are high in sodium, fat, or sugar can slow down your body’s metabolism and prolong the breakdown of THC. You can help expedite the process by choosing healthy, nutritious meals and snacks.

Detoxing kits

If you are worried about an impending drug test, you may be curious about the products on the market that offer “THC detoxing.” While some THC detoxing kits may work, contrary to popular belief, many don’t aim to “flush” THC from the body. They instead work by masking THC with other vitamins and proteins, which can lead to void drug test results. Also, THC detox products are not approved by the FDA, which means that many options on the market are overpriced, inefficient, and even dangerous.

Can CBD Show Up On Drug Tests?

CBD is the second most prominent cannabinoid in cannabis, but it’s not the same thing as THC. This is because many CBD products contain negligible levels of THC. Therefore, in most cases, CBD products will not cause a positive result on a THC drug test. Just make sure that you read the label carefully—if you are using a product that includes a mixture of both CBD and THC, or a full-spectrum CBD product, this runs the risk of being detected on a test.

Final Thoughts

Marijuana testing is a fickle business. It can be hard to definitively answer how long THC stays in the urine because the way that cannabis is stored in the body varies widely by the individual. The sensitivity of various tests can also vary widely. As a general rule, it’s fair to assume that most infrequent to moderate users of marijuana can expect all traces of weed to be undetectable in their system after 30 days for a urine test. However, the detection periods for other methods may be longer. The only way to be 100% sure that you’ll pass a THC urine test is to stop using THC entirely.