How long does marijuana stay in your bloodstream?

How long weed remains in your bloodstream can be a very important question. If you use marijuana products and you are involved in a traffic stop or a traffic accident you could be required to provide a blood sample to test for THC, the psychoactive component of marijuana. A positive test could result in your arrest for driving under the influence or in some states, for using an illegal substance.

It turns out that the answer to the question of how long pot or THC remains or can be detected in your bloodstream is not a simple one. A whole lot of factors determine how long cannabis products stay in your bloodstream and your body.

What is marijuana?

The answer to the question as to how quickly marijuana will clear out of your bloodstream is a difficult one but before we even get to that, let’s be sure that we understand what we are talking about. Marijuana is made from the dried flowers or buds of the Cannabis plant, most commonly the Cannabis sativa plant. The psychoactive component of marijuana or weed is THC or Tetrahydrocannabinol, which is what causes the so-called “high” from using it. Marijuana is usually consumed by smoking a so-called “joint” or by consuming an edible such as a gummie or a cookie or a brownie but it can also be consumed in coffee and tea as well. CBD or Cannabidiol is a non-psychoactive part of marijuana which is now legal in all 50 states of the USA and does not show up on blood or urine tests for weed.

Tests for marijuana

The blood test

Blood testing is primarily used in the investigation of traffic stops and road accidents for the detection of marijuana. There is no reliable breath test for marijuana like there is for alcohol. The test used for the detection of the blood levels of cannabinoids that is THC itself or its metabolites including THC-COOH is a two-dimensional gas chromatography-mass spectrometry test and is very specific for both THC and it’s main metabolite THC-COOH. The blood test is different from the EMIT test commonly used to test urine which measures only THC-COOH. In general, after a single use of marijuana blood tests will be negative in about 24-72 hours.  However, a 2009 study, published in the journal Addiction, found that cannabinoids were present in the blood of 6 of 25 chronic weed users even after 7 days of supervised abstinence.

The urine test

The most common test for marijuana, the EMIT urine test, does not actually test for THC itself but tests for THC-COOH, which is a metabolite of THC formed when THC is broken down in the liver. THC-COOH then passes back into the bloodstream and is filtered out of the blood by the kidneys and thus appears in the urine. A urine test for THC-COOH is said to be positive if the amount is 50 nanograms per milliliter or more. THC-COOH is fat soluble and stays in the body much longer than THC itself so that urine tests are a better measure of previous marijuana use but blood tests are a  better measure of current or very recent use. Marijuana tests required by employers are almost always urine tests because obtaining blood samples for testing is invasive and difficult.

Factors which affect how long marijuana stays in the bloodstream.

  • What is the strength of the marijuana product that you use?
  • How frequently do you use it?
  • Do you smoke it or use an edible like cookies or brownies?
  • How much body fat do you have?
  • How fast is your metabolism?
  • How much exercise do you do?
  • What type of food do you eat and when?
  • What type of test must you undergo, such as saliva, blood, or urine?

How long does it take Cannabis to leave the bloodstream and the body?

So, let us discuss those factors which affect how long cannabis products stay in the bloodstream and the body. Perhaps the most important factors are the concentration of THC in the weed that you are smoking or the edibles that you are eating and how often you use them. Unfortunately, the US Food and Drug Administration considers marijuana a Schedule I Drug which means it has no recognized benefit and has the potential for abuse and addiction. As a result, there is no FDA control over marijuana and no standardized way of measuring the strength of THC in any product one might use. In short, you have no reliable way to know the concentration of THC in any Cannabis product.

How often you use marijuana

Regardless of the concentration of THC in any marijuana product, the frequency of use is the major factor in determining how long THC-COOH can be detected in a urine sample. Frequent use results in a gradual accumulation of greater and greater amounts of THC and thus greater and greater amounts of THC-COOH. In general, if you use weed only once your blood will only test positive for 24 hours or so but urine will test positive for about 5-8 days afterward. On the other hand, if you are a chronic smoker, using marijuana say several times almost every day, you could test positive for many weeks or in some cases even 2 or 3 months after you stop using it! As mentioned, chronic users can even show positive blood tests 7 days after supervised abstinence.

Body type and metabolism

Body type and metabolism also play a role in determining how long marijuana or more correctly THC-COOH can be detected in your blood or urine. THC-COOH is stored in fat cells and people with large amounts of body fat will store more of it and therefore it will appear in blood or urine specimens for longer. People with high percentages of body fat also tend to have a lower metabolism and therefore burn THC-COOH more slowly and so that also contributes to it being detected for longer periods especially in urine specimens.


Exercise, especially vigorous exercise, will increase your metabolic rate and therefore burn THC-COOH more quickly and reduce the amount of time it will be detected in your blood or urine. Vigorous exercise causes your fat cells to burn and they then release the THC-COOH, so it is suggested that vigorous exercise should be done at least a few days before a urine test to avoid releasing THC-COOH from fat cells and unintentionally increasing the amount in your urine.

High fiber foods

Foods high in fiber tend to attract THC-COOH into the gastrointestinal system and promote its elimination via the colon thus reducing the amount in a urine specimen. Pectin, a complex starch that is often used to thicken foods such as jellies, is a high fiber substance which can be used to reduce THC-COOH excretion by way of your urine and cause it to be eliminated by way of the colon and feces.

As I think you can see, there is no reliable answer to how long marijuana or it metabolite THC-COOH will be detectable in a blood or urine specimen but, unfortunately, only sustained abstinence can guarantee a negative test. In general, THC is cleared from the bloodstream more quickly and THC-COOH is cleared from the urine much more slowly. Also, you will most likely not have advanced warning of an upcoming blood test because they are usually only used for traffic stops or road accidents BUT that should be a warning that it is dangerous to use marijuana products if you are contemplating driving a motor vehicle. In fact, after using weed is recommended not to drive a motor vehicle or use dangerous power tools or climb on ladders or in general do anything where judgment and coordination are involved.

How to help pass a test for Cannabis.

So, what can you do if you are faced with a required urine test by your employer on short notice if you are a regular user of weed? Of course, stop using it as quickly as possible but what else could you do to help you pass the test? One of the best ways is to use one of a number of commercially available detox drinks or pills. These drinks are combinations of a number of vitamins, diuretics and other substances designed to actually aid in detoxifying your body from THC-COOH. It is important for you to follow the directions for use of these products very carefully because the timing of their use is very important in determining how effective they will be. Simple aspirin, when taken 4-6 hours before a urine test, can reduce the measured amount of THC-COOH by as much as 50%. Drinking large amounts of water shortly before the urine test has also been suggested as a way to “flush out” THC-COOH but if the urine specimen becomes too dilute it will be declared not valid and another test will be required and you will be suspected of having manipulated the test.

If you have time, get one of the commercially available home test kits and test your urine to be sure that you are “clean.” In that way, you can be confident of passing a test required by your employer. There are no home tests for blood levels of THC or its metabolites but usually, you won’t have advanced notice of such a test although if a home urine test kit shows negative, a blood test will surely be negative too. Sometimes blood tests are required by employers or others if a urine test gives a questionable result to in that case you might have advanced warning of an upcoming blood test.

As you can see, there is no clear cut answer to how long marijuana or THC or its main metabolite THC-COOH stays in the bloodstream or how long it will show up in blood or urine tests but you now know the various factors which go into determining that length of time. Now you can be prepared to take any blood or urine test and be pretty confident of successfully passing it! Good luck!!!

Marijuana Detox Help