How Long Does THC Stay In Your System?

In the following article, you will learn about the most important drug tests and how far back they go to indicate marijuana consumption. However, there are a certain caveats you should know about.


Such factors are:

  • how often the applicant uses marijuana
  • the dosage of THC in the applicant’s body
  • the date of the last consumption session
  • the applicant’s metabolism
  • the applicant’s digestive function particularities

How long does THC take to disappear from one’s blood?

The studies conducted so far show that THC levels drop in the blood, depending on the method used to administrate the drug.

Keep in mind that each person has their own particular traits and even in regards to their drug use habits, there are no two people who share the exact same profile. This means that while you know that THC levels lower with time, your own habits, like how often you smoke, or how much you smoke, can greatly influence the final results of any study of this kind.

Here are some interesting findings you may want to learn about:
for instance, if you choose to smoke marijuana, the THC levels in your blood will show a spike, and then they will lower below the standard threshold of 50 ng/mL used by most tests
however, if you eat marijuana, in the form of brownies, the THC levels will elevate, reaching a peak within four hours
the metabolite identified by drug tests, THC-COOH, does not dissipate as fast as THC from your blood

Hair screening tests

The hair follicle drug test was designed to determine if the applicant is a long time user and it is not as efficient for one time users or casual users. Check out our homepage to learn more.

image of thc detection timesThese tests can establish if a person has used weed for the last week or more. Complex equipment and procedures are used in order to establish the presence of a metabolite named TC-COOH in the applicant’s blood. This metabolite is a byproduct of THC and it is used by drug screening companies to establish marijuana use. The threshold used for this metabolite is 50 ng/mL.

This value is not usually reached when the person getting tested is a casual smoker. To understand how unreliable these tests are for identifying casual users, take a look at these numbers: 85% of regular smokers were identified by these tests, and only 52% of those using weed up to five times weekly. The data was provided by the Cannabinoid Concentrations in Hair from Documented Cannabis Users.

Studies also show that eating marijuana instead of smoking it can determine tests to return a negative result, despite actually using the drug.

Urine screening tests

image of the urine drug test resultsCompanies often use urine sample to identify marijuana users.The same metabolite makes the subject of urine screening tests, and the same threshold applies.  However, since urine is quite sensitive to drugs, especially marijuana, urine screening is preferred by many companies. Basically, when the body eliminates THC-COOH through urine, this will appear in the sample provided for testing.

Unlike hair screening, urine screening is more accurate for casual users. Even a person who has used marijuana just once can be detected with the help of such a test.

Interesting enough, studies conducted so far show that different levels of THC-COOH can be identified in various persons, with great changes from one hour to the next. Such differences are important to speak about since they play a role in what kind of results you can get from a urine test.

The composition of a person’s urine can change a great deal due to various factors. For instance, if you drink a lot of water, the urine will be less concentrated, and smaller amount of various substances will be present in it. Also, those with a faster metabolism may eliminate THC-COOH from their bodies in a more efficient manner.

Since urine testing is particularly dangerous for casual users, it is recommended to avoid using marijuana a few days in advance.

Blood screening tests

Unlike the other tests that focused on identifying the presence of THC-COOH in the sample, a blood test will show the presence of THC, which is the main compound in the actual drug.

Blood screening has its drawbacks and it can only identify marijuana use for a few days before. For this reason, these tests are mostly used for events like crimes and accidents. Also, they are a good choice for spot testing in companies where drug use can lead to terrible consequences in case employees use marijuana or other illegal substances.

For situations when abstinence is imposed by a court of law, blood tests are also preferred.

Saliva screening tests

From all four types of drug tests, this is considered the most inaccurate for identifying marijuana consumption.

Here are some of the caveats of these tests, as they were identified by the Rosita Project, an important research project back in 2006:

  • not all applicants can provide enough saliva for testing
  • the equipment used cannot accurately provide results.

However, if the companies making this kind of equipment work on its improvement, saliva screening may become a reliable method to identify marijuana use.