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How long does marijuana (THC) stay in your system

Last reviewed by Editorial Team on September 4th, 2018.

Marijuana Facts

Marijuana or herbal cannabis is a drug or substance that is used for both recreational and medicinal purposes. The principal component of marijuana that warrants its use recreationally is known as tetrahydrocannabinol (THC).

The amount of THC in marijuana determines its potency and therefore, determines the duration and severity of its effects on the body . THC has a psychoactive or mind altering effect which changes normal brain activity or function, which is why most people use it to get the feeling of being “stoned” or “high”. Marijuana exists in different forms which includes synthetic, endogenous form and plant form.

The plant form is the most commonly used type due to ease of availability and access. The plant forms include sativa and indica. Marijuana is prepared from shredded leaves, stems and dried flower buds from the cannabis plant.

thc drug test

How long does marijuana (THC) stay in your blood, saliva, urine, hair, brain, breast milk or your entire system

Marijuana users and non- users alike seek to answer one question, “How long does marijuana stay in your system even if you smoke once ” To answer this question, one has to first understand that marijuana is just like any other drug. It therefore undergoes the same processing mechanism by the body, just like other drugs. This is known as pharmacokinetics or simply, “What the body does to the drug.”

What happens when marijuana (THC) enters the body?

THC has to undergo administration, distribution, metabolism and finally excretion. Marijuana is administered by inhalation, smoke, a paste and other different forms. Thereafter it is distributed in the body and then metabolized or broken down into simpler constituents or metabolites which the body can actually get to use.

Finally, the body gets rid of it via different excretory organs such as the kidneys and the skin, which then gets released into the urine, sweat, saliva or even the hair.

It is quite difficult to determine exactly how long the marijuana stays in your system. However, this can be determined using drug tests that are performed on body samples such as the urine, hair, blood, nails and saliva.

The drug can be detected in the body within a specific detection window, which is simply the length of time in days following substance usage, that sequentially collected samples will continue to produce positive drug test results.

To understand how this detection process works, one needs to know that the active component of the marijuana, THC, is actually absorbed by the fatty component of different organs in our body, including the brain. Factors that affect the detection window include the drug dosage, the route of entry, frequency of use and rate of metabolism. In addition, the test sensitivity and specificity also affect the detection window.

How long THC is found in urine?

The most commonly used detection sample is urine because it has higher detection of cannabis metabolites, has a longer detection time and is much cheaper because urine samples are easy to collect. However, there are also factors that determine how long the THC stays within your urine. These include, your weight, your body fat, how much “weed” you have used and how often you use the “weed”.

THC appears positive in the urine sample within 2 – 5 hours of use. The amount of time it remains in the urinary system is dependent on how often you use the marijuana. Let us classify frequency of use by: one timers, moderate users, frequent users, heavy users and heavy pot smokers. According to research done to determine how long marijuana stays in your body, the average is that it stays for several days ranging from 3 – 30 days after use.

Specific time frames in relation to frequency of use are: 1- 6 days for one time users, 7- 13 days for moderate users, 15 days or more for frequent users, 30 days or more for heavy users and a whopping 45- 90 days for heavy pot smokers AFTER QUITTING! Therefore, heavy pot smokers can quit smoking pot today but the urine will still continue to show THC for the next 45- 90 days.

Detection time for THC in saliva and hair follicles

Drugs tests that use saliva will give a positive THC result within 1 hour of use but positive results only last up to a maximum of 12 hours after use. The hair drug test shows positive results for THC 7 days after use but can go up to a maximum of 90 days, in some cases up to 3 years from the time it was used because of the fact that THC can be stored in the hair follicles.

Cannabis has a long half- life of about 67 days, which makes it particularly difficult to determine whether a positive result in a chronic cannabis user is due to a new episode of abuse or due to continued excretion of the residual drug. However, the half- life varies depending on the quantity of THC in the type of cannabis being used.

It is also worth noting that the more one takes the marijuana, the longer it will linger on within your system and the higher the chances of it getting detected in different tests. For example, chronic marijuana users that smoke a joint once every 6 weeks will have positive THC results for many years to come. This is because the THC will have bound to the body fats, as well as the hair follicles, so if one keeps smoking pot and does not have a hair-cut, the samples will continually give positive THC results.

How to get weed out of your system? Detoxification of marijuana

marijuana cleanse

Following drug abuse, there are unpleasant effects or personal decisions that prompt the user to seek withdrawal from the use of marijuana.
According to the DSM-IV-TR diagnostic criterion, cannabis intoxication is based on:

  • Recent use of cannabis
  • Clinically significant maladaptive behavioral or psychological changes (e.g, impaired motor co-ordination, euphoria, anxiety, sensation of slowed time, impaired judgement, social withdrawal) that developed during, or shortly after cannabis use.
  • Two (or more) of the following signs, developing within 2 hours of cannabis use:
    • Conjunctival injection
    • Increased appetite
    • Dry mouth
    • Tachycardia
  • The symptoms are not due to a general medical condition and are not better accounted for by another mental disorder.

From the diagnostic criteria described above, detoxification follows the level of intoxication. However, it should be noted that marijuana detoxification has unestablished and inconclusive research. Therefore, guidelines for marijuana detoxification are not fully and reliably established.

The insufficient availability of standard detoxification guidelines can be attributed to the fact that marijuana’s main active component, THC, is fat soluble. Therefore, it is quite difficult for researchers to develop a regimen or drug that will completely rid the user of the THC from the body fats, as well as the THC in the brain.

Cannabis intoxication can be classified as acute intoxication and chronic intoxication. Acute intoxication is observed within 45 minutes up to 2 hours of marijuana use by inhalation and includes physiological signs such as palpitations, dizziness, cough, tachycardia, xerostomia and increased sensitivity to light. Psychological signs include increased mental activity and talkativeness.

Acute intoxication presents with the sensations such as improved social sensitivity, improved self-awareness, enhanced sexual experiences and a feeling of calm and relaxation. Chronic intoxication presents in users that abuse marijuana every 6 weeks for at list 2 years and has a major effect of altering cognitive processes.

Chronic intoxication is characterized by intermittent episodes of acute intoxication and has certain implications on the user such as that of not being able to perform activities without using cannabis and there is diminished intellectual capacity.

Cannabis use is also associated with delirium which is characterized by impaired cognition and performance of tasks, resulting in impairment of memory, perception, attention deficit and slowed reaction time. High dose of marijuana is associated with impaired levels of consciousness.

The detoxification process seeks to reduce and eventually eliminate the above symptoms and signs. Despite insufficient data, detoxification of cannabis uses the same principles as that of detoxification of other substances of abuse. The process of detoxification combines both pharmacological and psychotherapeutic methods.

The major difficulty with getting rid of the cannabis is that its active component, THC, binds to fats in the body. Psychological counseling has proven to be the most effective method of dealing with marijuana abuse and it has long term results, as it addresses the patients’ attitude towards the use of the drug and also seeks to change the behavior pattern that prompted the user to begin taking the marijuana in the first place.

The psychotherapeutic method is commonly used and involves abstinence and support. Abstinence is divided into 3 phases which are medical, psychological and social phases.

During the medical phase, the patient can be hospitalized, or can be carefully monitored by qualified healthcare providers on an outpatient basis by the use of urine drug screens, which can detect cannabis for up to 4 weeks after use and the use of pharmacological agents to lessen the withdrawal symptoms.

During hospitalization, the marijuana user is treated with activated charcoal, in the case of marijuana overdose which is commonly due to ingestion of cannabis. Intra venous fluids are also used to balance the patients fluid levels and the withdrawal side effects are commonly treated with benzodiazepines.

The psychological phase involves withdrawal effects that are experienced such as intense dreams during sleep, which can cause sleep disturbances. The social phase involves the last phase of abstinence, which involves the patients’ reduced interaction with social situations or environment, that initially contributed to the start of the abuse of marijuana.

For example, during the social phase, the marijuana addict can avoid interaction with friends that have continued to abuse marijuana. Support can be achieved through the use of individual, family, and group psychotherapies.

Despite extensive research, there are no recommended drugs for detoxification of marijuana. However, certain drugs will ease the process of withdrawal symptoms if the drug user is adherent to the regimen being used. Pharmacological agents that have shown to help in withdrawal of marijuana abuse includes anticonvulsants such as valproate sodium and antidepressants such as fluoxetine, mirtazepine and nefazadone.

It should be noted that these drugs only help to reduce the cravings but however, they increase irritability, anxiety and tiredness. Ironically, oral THC and lithium carbonate have shown better results in detoxification of marijuana. THC, in combination with lofexidine, helps reduce withdrawal symptoms and also reduce depressive episodes associated with withdrawal. This combination also reduces sleep problems, anxiety and cravings.

Other remedies and adjuncts used in the management of detoxification of marijuana include use of shampoos, capsules, mouthwashes and teas. All these remedies work principally as diuretics, thus they work by diluting the THC constituents in the urine.

This method helps to reduce the detection of the THC in the urine, but it also alters the composition urine such as the creatinine levels. Another method that helps the process of detoxifying marijuana from the body is by physical exercise. This will help burn the fats that are the storage places for the THC.


In conclusion, marijuana stays in the system for an average of 4 weeks, depending on the type of marijuana being used and how frequently it is used. In heavy marijuana smokers, it can stay for a period of more than 90 days, following the last use. It stays for longer in the body because its active component, THC, is fat soluble and hence it is stored in the body fat.

The detoxification process of marijuana intoxication depends on whether the user is in the acute or chronic phase. However, regardless of the phase, the process involves psychotherapeutic counseling as well as pharmacological methods. Detoxification of marijuana is particularly a slow process because of the binding capacity of the THC to fats in the body.

  • Alison M. Diaper, Fregus D. Law & Jan K. Melicher. Pharmacological Strategies For Detoxification. British Journal of Clinical Pharmacology, February 2014.
  • Grotenhermen Franjo. Clinical Pharmacokinetics Of Cannabinoids. Journal Of Cannabis Therapeutics, Vol.3(1) 2003, Hűrth, Germany.
  • Hahn RK, Abers L et al. Psychiatry (2003-2004 Edition). Current Clinical Strategies Publishing. California, USA.
  • Paul L, Cary MS. The Marijuana Detection Window: Determining The Length Of Time Cannabinoids Will Remain In Urine Following Smoking. A Critical Review Of Relevant Research And Cannabinoid Detection Guidance For Drug Courts. National Drug Court Institute. April 2006. Vol.IV.No 2
  • Semple D, Smith R et al. Oxford Handbook Of Psychiatry (2005) 1st Edition, Oxford University Press, Oxford, UK.
  • Thomas Lundqvist. AGuide To Quitting Marijuana And Hashish, Drug Addiction Treatment Centre Lund University Hospital.Lund, Sweden.
  • Winstock A, Lea t. Management Of Cannabis withdrawal. National Cannabis Prevention and Information Center, Sydney South West Area Health Service.

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