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How Long Does Marijuana (THC) Stay in Your System?

How Long Does Marijuana (THC) Stay in Your System?

Marijuana is the most commonly abused recreational drug in United States. A survey conducted in 2015 revealed that over 50% Americans have consumed marijuana at some point in their lives. Being considered less dangerous, its social acceptance is steadily increasing. Also, its legalization in certain states has further worsened the condition. The misconception that abuse of marijuana is not associated with any significant side effects needs to be addressed. The truth is, marijuana is an addictive drug and there have been many cases of marijuana addiction in the past. The recent studies have revealed that its long term abuse can cause permanent damage to mental health. It can not only harm memory but can also impair cognitive abilities. THC is the main chemical component present in cannabis associated with the feelings of euphoria and resulting side effects. When the use of marijuana is completely quit, THC tends to stay in the system for a while as the body works to remove it. Therefore, it becomes important to understand as to how long does Marijuana stays in your body.

How long does marijuana stay in your system?

Marijuana is a drug obtained from the plant ‘Cannabis sativa’. The dried leaves, stem and flowers of this plant are often filled in cigarettes and smoked. Occasionally, the dried marijuana seeds are also smoked. However, it is not a common practice since marijuana seeds do not contain significant amounts of the active chemical ‘THC’. Thus the seeds fail to produce any noticeable effects. Apart from marijuana obtained from cannabis sativa, a new product is also available in the market named as ‘synthetic marijuana’. However, it is a completely different product with completely different active ingredients. Synthetic marijuana is actually made from dried plant leaves sprayed with synthetic cannabinoids. THC, which is the main chemical present in herbal marijuana, is not present in synthetic marijuana. It can be more harmful than herbal marijuana.

After quitting the use of marijuana, THC tends to stay in the system for some days. It is particularly true in case of long term users. Some studies suggest that marijuana stays in the system for 25 days; others claim that it can persist for up to 11-15 weeks. It shows that the time taken for the removal of marijuana largely depends upon the amount and duration of its consumption.

  • Acute/Occasional/Infrequent users:

In case of infrequent or occasional users, the time taken for the removal of THC is short. Studies suggest that cannabinoids are unlikely to be detectable after a period of 4 days in case of infrequent users. An occasional user is likely to clear off most of the metabolites from marijuana within a period of 7 days. However, it does not mean that no trace of the drug will be left in the body, it only means that the concentration of the chemicals from the drug will drop to such a level that it will be no more detectable on a drug test.

  • Chronic/Long Term/Frequent users:

Although there are conflicts among individual studies and it is hard to establish a definite period, in case of most long term users, it takes about 10 days for the removal of most of the metabolites from the drug. However, the chemicals from the drug are still not completely removed; their level is only reached below threshold so they are no more detectable by a drug test. In case of some more sensitive tests, it may take 21 days before the drug becomes undetectable in the body.

It is clear that THC has a long half life and it takes quite some time for its removal. Passing a drug test can be a difficult task for long term abusers.

Factors that determine how long marijuana stays in your system:

According to Ryan Vandrey, an associate professor of psychiatry and behavioral science at Johns Hopkins University, there is no typical window of detection for marijuana. The duration for which it stays in the body is highly variable from person to person and it varies based on the frequency of use and the amount of use. Some factors that influence the time taken for its removal include:

  • Dosage of the drug (amount of THC):

The dosage of the drug taken, or the amount of THC administrated in the body is proportional to the time taken for its removal. If a person has smoked more quantity of marijuana, the window of detection will also be prolonged.

Establishing the amount of marijuana consumed can be a tricky task. Even a small amount of marijuana rich in THC is enough to elicit an extreme response. So while consuming the drug, it is important to keep in mind the concentration of THC present which determines how long does Marijuana stays in the body.

  • Frequency of use:

As stated earlier, long term and frequent users are likely to retain the drug in their system for longer periods of time. This is because with prolonged use, body is supplied with excessive amounts of THC that tend to accumulate in certain body tissues such as fat and hair. Over time, the stored drug is gradually released and removed from the body. As a result, the person tests positive for a much longer period. Greater the amount of stored THC and its metabolites, longer will be the time taken for its removal.

  • Mode of administration:

Marijuana can be consumed in a number of ways such as:

  • Smoking it in the form of joints of blunts
  • Eating marijuana containing brownies or gummies

The mode of administration influences the way THC is absorbed, metabolized and excreted   from the body.


In case of smoking, THC is directly absorbed in the blood via lungs. As a result, the effects produced by it are quick. The blood levels of THC reach their peak values within 10 minutes of smoking and they are just as quick to fall. In case of most occasional or first time users, the drug levels drop by 60% after the last puff. Within 3-12 hours, the levels fall below detectable range.

Oral ingestion:

Consuming marijuana edibles such as brownies or candies produces slow and long lasting effects. As the drug is slowly absorbed into the blood from GIT, it may take 1-5 hours to feel the effects. The time taken for the drug to reach its peak values in the blood depends upon the concentration of THC in the oral formulation. Usually, the blood levels of the drug begin to fall within 24 hours of last consumption. However, some metabolites from the drug may be present in the blood for as long as 50 hours post ingestion.

  • Individual factors:

Individual factors such as age, gender, metabolic rate etc also influence the clearance rate of the drug. Some people are likely to clear off the drug faster than the others even after consuming the same amounts.

  • Height/weight/age/gender:

Factors like height, weight, fat content, gender and age of the user influence the time taken for its removal. People with more fat content have a hard time removing the drug from their system since it gets accumulated in fat cells. Likewise, people with more body mass are quicker to remove it than the people who take high amounts compared to their body mass.

  • Metabolic rate:

Metabolic rate of a person plays a key role in determining the time taken for THC removal. People with an active metabolism excrete the drug at a faster rate. People with slow metabolic rate take longer to convert THC into its metabolites.

  • Polysubstance abuse:

Taking other substances in combination with marijuana can slow down its clearance rate. It is commonly combined with alcohol and the body has to work to remove both the substances simultaneously. However, some supplements can be helpful to speed up the process of THC removal.

  • Active lifestyle:

An active and healthy lifestyle can facilitate the process of THC removal. Doing regular exercise and yoga can help to speed up metabolic rate. Heavy marijuana consumers with an inactive lifestyle may take longer to clear the drug from their system.

Marijuana metabolism and time taken for its removal from the body:

Since THC is the main chemicals associated with the euphoric effects produced by the drug, it is the chemical that is detected during drug tests. The time taken for the absorption and reaching peak values varies depending upon the mode of administration. In case of smoking, blood concentrations peak within 10 minutes while in case of consuming edibles, it may take up to 5 hours. Likewise, when smoked, marijuana is removed from the system faster as it is distributed throughout the body and is metabolized by the liver.

THC is a fat soluble compound so it is often stored in fat cells. As it passes through heart, liver, lungs and brain, these organs tend to retain the chemical and that may last for much longer periods compared to blood. In case of regular users, THC may persist in tissues for up to 4 weeks.

Liver is the main organ involved in the metabolism of THC. Other organs like lungs, brain and kidney may also aid the process. In most of the cases, about 80 to 90% drug is removed within 7 days. Studies show that 60% of the drug is excreted via feces while 20% is excreted via urine. However, individual variations may occur.

Half life of THC:

Half life is the time taken for the removal of half of the drug consumed. Since THC is water insoluble but highly soluble in fat, it tends to accumulate in fatty tissues of the body. As a result, it tends to have a longer half life. The average half life of THC is estimated to be 3-4 days. It means that it takes around 3-4 days for most people to remove half of the drug from their body. However, the half life is subject to significant individual variations. Above mentioned factors like metabolic rate, age, gender, overall health, frequency and dosage of use can affect half life of THC.

Different types of drug tests used to detect marijuana (THC) in system:

A number of drug tests are used to detect THC in the body of the user. The threshold value of THC and its metabolites for detection is 50ng/ml. however; some tests can detect as low amounts as 20ng/ml.

  • Urine tests:

Urine tests are most commonly performed for the detection of metabolites of THC since they are non-invasive and easy to perform. Urine samples are collected from suspects and tested for the presence of an inactive metabolite ‘THC-COOH’. For most urine tests, threshold value for the metabolites is set at 50ng/ml.

Urine tests are usually effective for 1 to 3 days after marijuana consumption, and knowing how long does Marijuana stays in your urine can be helpful. Metabolites start to show in urine within 2-5 hours of consumption. The accuracy of urine test is decreased after a week but it can still be used in some cases.

  • First time user: A first time user may test positive on a urine test for up to 7 days.
  • Moderate user: An occasional user may test positive on a urine test for up to 14 days/2 weeks.
  • Regular user:Regular users tend to test positive for marijuana for up to 21 days or 3 weeks.
  • Heavy users:long term heavy users may test positive for marijuana for as long as 60 days/2 months after cessation.
  • Hair tests:

A sample of hair is collected from the user and tested in laboratory for the presence of THC. In case of long term users, THC is build up in hair. The advantage of using a hair test is that it may detect marijuana for up to 3 weeks. However, it does not detect a recent marijuana use.

  • Saliva tests:

Salivary fluid is taken and tested for the presence of THC within 1-2 hours post ingestion. However, salivary tests are not as accurate as urine tests. Also, the short detection window makes them seldom used.

  • Blood tests:

Because of their invasive nature and difficulty to perform, blood tests are rarely used, but still you need to be aware as to how long does Marijuana stays in your blood. They are used to determine if THC is present in the blood. Blood tests are usually used by law enforcement agencies to determine if someone is driving under the influence of marijuana. A blood test can be used for up to 3 days after last drug use. In case of long term users, it can be applicable for up to 4 weeks.

Harmful effects of marijuana:

ong term abuse of marijuana is associated with a number of harmful effects such as:

  • Slow respiratory rate
  • Drowsiness
  • Poor coordination
  • Memory deficits
  • Cognitive deficits
  • Mood swings
  • Hallucinations
  • Anxiety
  • Paranoia
  • Panic attacks
  • Impaired judgment
  • Psychosis

Apart from these effects, cancer causing potential of marijuana is a topic of discussion these days. The question is:

Does marijuana really cause cancer?

Unfortunately, not enough studies are currently available to deny or confirm marijuana’s cancer causing potential. The chemical components in marijuana’s smoke are same as in tobacco’s smoke with a difference of main active ingredient. In case of marijuana, main active ingredient is THC while in case of tobacco, it is nicotine. The cancer causing potential of tobacco has been confirmed after years of research. Marijuana smoke may as well prove to be carcinogenic one day.