How Long Does Marijuana Stay in Your System? | An In-depth Analysis

How Long Does Marijuana Stay

Marijuana, or weed as it is commonly known, is a very addictive drug that has a wide range of negative mental, social, and physical health effects. Its effects can be quite strong and are usually felt almost immediately.

However, the “high” that users get from weed does not usually last long and begins to fade soon after the users stop taking the drug. What most people do not know is that weed stays in the system for a much longer time than they assume.

Even after the user feels okay, many drug tests can detect marijuana in the system. As such, it is not unusual for a person to test positive for weed many days, or even months, after using the drug.

It is therefore very important to educate people, especially the youth, on the dangers of drug addiction. Data gathered by the Substance Abuse and Mental Health Services Administration (SAMHSA), indicates that 10% of regular marijuana users develop an addiction to the drug.

This article will explore the body’s interaction with marijuana, in particular THC. It will also look at the various factors that affect how long weed stays in the system, the drug tests commonly used, and how to beat drug tests.

What Is THC?

Tetrahydrocannabinol (THC) is a cannabinoid derived from the cannabis plant, and that has psychoactive effects on the body. There are 113 known cannabinoids in weed, but THC metabolites are the important ones when talking about the effects of marijuana or cannabis use.

According to the Substance Abuse and Mental Health Services Administration, when marijuana is abused, it is the THC that can cause acute psychosis and other negative impacts on the body.

Cannabis plants do not all have the same amount of THC concentrations, which is a major factor in determining the effects of marijuana, withdrawal symptoms, the accuracy of a drug test, and how long weed stays in the system.

How Does Your Body Process THC?


To understand how marijuana affects the body, it is important to look at how THC is processed once the weed has been ingested or inhaled.

As soon as marijuana is used, THC enters the system quickly and is absorbed by different body parts, such as the brain, body fat cells, and the heart. The liver plays a very important role in processing THC by metabolizing it to carboxy-THC (metabolites) and 11-hydroxy-THC.

The body works hard to expel as much cannabis as possible, with 65% being excreted through feces and 20% through urine. This leaves a massive 15% that is stored in various parts of the body.

With time, the body will slowly release the THC back into the bloodstream, and the liver will metabolize it. However, the process is very slow, and in individuals who take a lot of marijuana regularly, their THC levels will remain high despite the liver metabolizing as much as possible.

It is, therefore, common for positive tests to be obtained from a blood or urine sample many days or weeks after chronic users last took any marijuana. Over time, though, if drug use is brought under control, for example, in a drug treatment facility, the body can eliminate THC metabolites from the system until it is no longer detectable using any conventional drug test.

How Long Does Weed Stay in Your System?


The question that most people ask, especially when facing the possibility of a drug test, is “How long is marijuana in your system?”

To understand how long marijuana will be detectable using a urine test, hair test, or any other drug test, it is important to know what the half-life of THC is. This is the time it takes for THC levels in the body to reduce to half of their current concentrations.

The half-life of THC levels is highly affected by the frequency of use. In users who do not regularly use marijuana, the half-life of THC can be as low as 1.3 days. This is a very quick turnaround compared to between 5 and 13 days, which is how long the half-life of THC levels is in chronic users.

Another important factor is where the THC stored in the body is located. THC metabolites stored in the blood have a half-life of about 24 hours, while any THC absorbed in the body fat has a half-life of up to two weeks.

This is why, to gauge whether or not THC will be detected in the body, it is important to know the type of test that will be administered.

Four Common Drug Tests Used to Detect Marijuana

Drug Test

The legalization of marijuana use is an ongoing process throughout the United States, but many drug testing facilities still test for THC metabolites. In most cases, the result obtained from a drug test depends on the type of test administered.

There are for main methods used in THC drug testing, and these are:

  • Saliva tests
  • Urine tests
  • Blood tests
  • Hair tests

Considering that a positive drug test can have very serious consequences, for example, when investigating the causes of a fatal car accident, it is important for marijuana users to understand each of these four THC drug test methods.

Interviewing for a Job Soon?  Read how to pass a marijuana drug test.

Saliva Tests

The simplest way to detect marijuana in the system is by using a mouth swab to administer a saliva test. This is a quick and non-invasive THC drug test that is routinely used for on-the-spot tests.

When marijuana is taken, a lot of it is absorbed into the mouth. During the test, a cotton swab is used to take a saliva sample from the tongue or inner cheek. This sample can result in a positive drug test 24 hours after drug use.

Urine Tests

Since 20% of THC is excreted through the urine, a urine sample can be taken for testing to check if there is any THC in the system. A urine test is one of the most common ways of testing for THC.

The results of a urine drug test are highly affected by the frequency of use of marijuana. Urine tests can detect marijuana up to three days after use in infrequent users. Those who use marijuana moderately can receive positive test results five to seven days after using weed. However, in chronic users, a urine test can pick up THC metabolites even a month after smoking marijuana.

Blood Tests

When marijuana users take weed, THC levels rapidly increase in the bloodstream. However, the liver will actively metabolize THC and reduce the amounts in the blood very quickly. As a result, the window period for detecting marijuana using blood tests is very small.

This is why a blood test is not commonly used to test for THC. Even with chronic use, marijuana will only stay in the bloodstream for up to 48 hours before becoming undetectable.

Hair Tests

Marijuana can stay in hair follicles for even longer periods than it does in body fat. As such, a hair test can detect THC up to three months after the user last smoked marijuana. This is particularly true in chronic users of weed, but not so when it comes to light users.

The downside of hair tests is that, while they can detect THC over a much wider window period, they cannot be used to determine how much marijuana was taken. This means, in cases where the level of intoxication needs to be determined, hair tests are ineffective.

What Factors Impact How Long Weed Stays in Your System?

Marijuana Consumed

There are many things that determine how long weed, in particular THC metabolites, stays in the body. The following are some of the common examples:

Amount of Marijuana Consumed

The more marijuana that is consumed, the higher the THC levels will be in the body. There is only so much THC that the liver can remove from the blood. This means if a large amount of weed is ingested at once, it will take much longer to excrete it.

Method of Consumption

If users smoke marijuana, the drug has a direct route to the bloodstream when it is absorbed through the lungs. This means it will likely be quickly metabolized and leave the system faster.

However, in users who prefer to ingest marijuana through various edibles, it will take a lot longer for the drug to be absorbed by the body and eliminated. Such individuals are likely to test positive for THC for much longer periods.

Frequency of Use

Chronic users of marijuana will finally reach a level where the rate of consumption exceeds the rate of elimination of THC from the system. This means that even after they stop taking the drug, their bodies still have a lot of catching up to do, and will test positive for much longer.

Dosage of THC

Different cannabis plants have different amounts of THC compounds. This means a person can take a very small amount of a particular type of marijuana and test positive for THC for a longer period of time than someone who took a lot more marijuana that contained less THC.

Usually, the stronger the “high,” the more the THC in the marijuana. Therefore, users who constantly chase a more intense “high” to feed their addiction will have THC in their systems for much longer.


The rate at which the body metabolizes THC differs from one individual to the next. If a person has a high metabolism, they can expel all the THC from their systems at a much faster rate than those with a slow metabolism.


Other factors that affect metabolism, such as exercising, must also be considered. People who maintain an active lifestyle are more likely to be able to expel THC from their bodies at a much faster rate than those who lead a sedentary life.

However, users have to be careful because exercising right before a drug test will not have the effect they are hoping for. When a person exercises, the body will start breaking down fat cells to provide energy. Since fat stores cannabis metabolites, this will release any THC back into the bloodstream, resulting in a positive test.

Body Mass Index

A higher body fat concentration, or body mass index (BMI), means that a person’s body fat molecules are available in large numbers. This provides the perfect place to store THC, and when the drug tests are administered, they will pick up the compounds in the fatty tissues.


The higher levels of body fat in women generally mean that they can absorb and store a lot more THC than males. As a result, they metabolize and expel THC at a very slow rate.

Does Weed Drug Testing Have False Positives?

Yes, false positives can occur in any type of drug testing. Although common tests can detect THC accurately, false positives do happen. A false positive is when a test indicates that a person has THC in their system why they do not.

Some certain medications or products are known to cause THC false positives, such as dronabinol, ethacrynic acid, efavirenz, riboflavin, NSAIDs, promethazine, and baby soaps.

If a false positive is suspected, or if the consequences of a positive result are very serious, further tests can be administered, using more sensitive equipment, such as a gas chromatograph-mass spectrometer (GCMS).

A second positive test using more accurate equipment can leave no doubt that the person has marijuana in their system.

How to Beat a Weed Drug Test

People faced with the prospect of testing positive for a THC drug test usually look for various products and methods that can help them beat the test. One of the most popular ways of doing this is by using a detoxification kit for marijuana metabolites.

Most detoxification kits contain products such as ginseng, dandelion, and milk thistle. There has not been a lot of research on the effectiveness of these products, but, when faced with the prospect of failing a drug test, people are usually willing to take the risk.

Other common methods include using synthetic urine, submitting someone else’s urine sample, or trying to mask the presence of THC using various chemicals, such as bleach or ammonia.  A THC detox is also popular.

However, the best way to avoid a positive THC drug test is to practice abstinence and avoid taking marijuana. All other methods can be ineffective or, at times, very dangerous. Some of the chemicals that are found in certain detox kits have the potential to cause serious damage to the liver and other organs.

Help Is Available for Victims of Drug Abuse!

Marijuana drug addiction is a serious issue that requires a lot of care, understanding, compassion, and addiction treatment. Besides failing a drug test, this addiction has a lot of negative impacts on a person’s life, work, education, health, and relationships.

However, despite knowing all these things, chronic users of marijuana find it difficult to let go of their addiction, especially when it comes to dealing with the withdrawal symptoms. In most cases, a drug addict will require a lot of help from family members and friends to fight their addiction.

Those who find themselves struggling with marijuana addiction should seek help fast. Many treatment facilities across the USA are available to help addicts to kick their drug habit.