One of the most frequent questions that we are asked at Zoom Testing is “How Long Does Cannabis Stay in Your System?”
Many users of cannabis are often concerned about how long marijuana or hashish will remain detectable in their body. Certainly, nobody wants to risk losing his or her driving license or to test positive as part of a workplace drug investigation.
While there is no definitive answer to this question, we can give some guidelines. However, the only certain way to know is by carrying out a test with a cannabis drug test kit.
How long does THC stay in your system?
The detection times for cannabis in the body vary greatly, depending on the type of drug testing carried out. The other important factor is how intensively the product was consumed prior to testing.
There are four types of drug testing for cannabis that are commonly used – blood, saliva, urine and hair testing.
There are also a number very important factors that will influence how long THC will be present in your urine. These include:
- Body Fat
- Amount Used
- Frequency of Use
Since these factors can vary greatly for each individual, there are no definitive guidelines to tell you how long you can test positive for THC.
Detection times of Cannabis in Blood
THC is only detectable in blood for a few hours after last use. However, the degradation metabolite of cannabis, THC-COOH, can be detected for a longer period of time if the person being tested has taken the drug regularly.
A blood test for cannabis is normally only carried out by the police. This may happen after a road accident or traffic incident. Or it may be a follow-up test after a positive urine test for cannabis.
Detection times of Cannabis in Saliva
Detection of cannabis in saliva can be difficult as the drug is only detectable for a few hours. After this time, a saliva test for cannabis will come up negative. This is because a saliva drug test only checks for THC and not the degradation product / metabolite of cannabis, THC-COOH. Therefore, a saliva drug test for cannabis is best used when you suspect that use of the drug has taken place only a few hours before the test.
Detection times of Cannabis in Urine
How long cannabis is detectable in urine will depend on a number of factors. The most important variable is the how often the drug has been used by the person being tested.
If a person is being tested for cannabis, and they have only used the drug once, we can say with relative certainty that the detection time for the drug in urine will be 1-3 days after consumption.
The detection time for the drug becomes substantially greater if the person being tested has used cannabis more than once or heavily over a period of time.
Detecting the metabolite THC-COOH
A urine test for cannabis detects the metabolite THC-COOH. For regular users of cannabis, the metabolite will build up in the body faster than it can be eliminated in urine. This means that regular cannabis users will potentially be able to produce positive drugs tests for up to 2-3 months after last use of the drug.
On a urine drug test for cannabis, THC will appear as a positive within 2-5 hours of use. In the table below, we estimate how long the drug will take to leave the body based on frequency of use. We have not taken into account the weight and body fat of the cannabis user, which can affect the results:
- A one-time user of cannabis may show positive for 1-6 days
- A moderate user may show positive for 7-13 days
- Frequent users can show positive for 15 or more days
- Heavy users of cannabis can show positive for 30 or more days
- In extreme cases, some heavy users have reported being positive 45-90 days after quitting
A urine drug test for cannabis is often used by employers for workplace drug screening. This type of test can also be used by the police for testing drivers of vehicles. A Zoom Testing Cannabis (THC) urine test allows you to test urine samples for traces of THC, in the same way that an employer or the police would do.
Detection times of Cannabis in Hair
Hair has a way of keeping a permanent record of substances consumed. This means that if you have long hair, then you have a greater chance of testing positive for cannabis if you have been using the drug.
Normally, hair grows at a rate of about 1cm per month. So, if your hair is 6cm long, then potentially that provides a 6-month record of drug consumption.
A Hair Follicle Test for THC can be ordered for home testing, with the hair sample being sent to a lab for testing and analysis. Such a test can be carried out for both private and legal reasons.
Is It Possible To Fool A Cannabis Test?
You might have come across ways to fool a cannabis drug test, but most of them are urban legends. Here are a few of the not recommended techniques:
- Cleansing Your System: Some people try drinking large amounts of water or other liquid. They then pee numerous times prior to their test. This, whilst ingesting vitamin B-12 to give the urine back its natural colour. This might help to dilute the urine and eventually reduce the THC percentage found in it; however, the THC metabolites aren’t fully eliminated.
- Taking Drug Masking Agents: There are herbal teas and a number of substances available for sale that claim they will clean any traces of cannabis from the body. This has not been scientifically proven. The drawback is that they need to be used for long periods, but the body will naturally get rid of the THC anyway.
- Interfering With the Test: This is when a foreign substance is added to the urine to pollute the sample. Bleach, salt, Visine and detergents have been reported to be used, however, they are easily detected in the tests. There are urine test adulterants available for sale, but they are not foolproof. If the lab does a separate test for these substances, they are easily detectable.
Short Notice Drug Test? The Probability of Failure is High
For employers, workers who abuse drugs and alcohol present a serious risk. Most employees have a drug policy in the workplace that randomly test current employees and it is for all new employees.
If you recently smoked cannabis and have to take a urine test in a short time-frame for employment or other reasons, there is a high likelihood you will fail the test. The probability is even higher for regular cannabis smokers.
Even if your state has legalized the use of cannabis for recreational purposes, you could still be fired for failing that drug test.
The only way to guarantee that you will pass the test is to not smoke cannabis or ingest any products with cannabis.
This post has been updated since its original publication in 2017.