Fraser Horton
Fraser Horton
Last Updated on October 18, 2021

Maybe you smoked weed recently and you’re scared that your psychoactive escapade will show on your pending drug test. Naturally, you might be wondering about the length of time needed for the body to detox from cannabis use. 

First-time marijuana smokers have all kinds of questions when it comes to cannabis consumption, and one of the most common ones is how long can weed be detected after consuming it only once and how long does it take for THC to leave your system

The answer depends on whether you’re an occasional or a chronic user, as well as on the testing method used. 

Previously, we have covered the subject of passing a drug test if your last use was just a week ago, and in this article, we’ll focus on the detection time after a single use of marijuana.

How Does Your Body Metabolize Cannabis?

The two main cannabinoids found in weed are THC and CBD, the former being the psychoactive ingredient that produces psychoactive effects when it’s absorbed in the bloodstream.

Once in your body, this active ingredient is absorbed into the bloodstream, with some THC being stored in fatty tissues and organs for a while. 

After absorption, THC is broken down into more than 80 metabolites in the liver. The most important among them are 11-OH-THC (11-hydroxy-delta-9-tetrahydrocannabinol) and THCCOOH (11-nor-9-carboxy-delta-9-tetrahydrocannabinol). 

These are the exact metabolites that will show in drug tests since they stay in the body for a longer amount of time. As time passes by, these metabolites are released via urine and stool. So let’s get into how long it takes for the body to detox from them.

Drug Tests and THC Detection Times

Drug tests are the tools that measure the presence of weed, its by-products, and metabolites in the body. Metabolites of THC and CBD remain in your system long after the weed’s effects have worn off. 

Generally, these tests determine the concentration of THC metabolites (THC-COOH) in your body. Commonly used drug screenings include:

  • Urine test (this is the most commonly used test and it’s done by testing a urine sample for the presence of illegal drugs in the body);
  • Blood test (this type of drug testing is done by drawing blood and testing it for the presence of drugs and opiates);
  • Saliva test (the oral drug test, is done by taking a swab of saliva and testing it for the presence of drugs and opiates);
  • Hair test (the hair follicle test offers the biggest detection window and it’s done by testing the hair follicle for the presence of drugs and opiates).

What Influences Drug Testing Results and How Long Does Weed Stay in Your System?

There are a number of factors that influence how your body processes and metabolizes weed and how long weed stays in your system. For example, weed that’s ingested may remain in your system slightly longer than weed that’s smoked.

Like with all tests, there are certain factors that influence a higher chance of you getting a negative or positive result on your drug screen and those include:

  • The amount of THC consumed (the more weed you consume, the longer the detox period is);
  • The frequency of use (infrequent users have lower detection rates compared to frequent users);
  • Your hydration levels (water helps to detox the body, so the more hydrated you are, the faster your body will detox);
  • Your physical activity, metabolic rate, and body mass index (because THC binds to fat cells and fatty tissues in the body, marijuana detection of weed depends on your BMI and other factors that have to do with the amount of body fat you have); 
  • Other conditions users might have.

How Long Does Weed Stay in Your System After Smoking Once?  

The time frames for weed detection by using different kinds of tests are as follows:

  • Urine test (it has a 72-hour period for detecting THC metabolites for one-time users, although in chronic users the detection time may be up to a week);
  • Blood test (this type of drug testing can yield a positive result for infrequent users from 4 to 24 hours after the use of cannabis, and up to a week for frequent users);
  • Saliva test (if taking an oral drug test, you might test positive for up to 3 days if you’re an occasional user, and up to 29 days if you’re a heavy user);
  • Hair test (the hair follicle test offers the biggest detection window for cannabis use which is up to 3 months, although this test is done the least often since it’s the most expensive).

Final Thoughts on Detoxing From Marijuana Use

While for daily users the time frame for passing the drug test is smaller, first-time users don’t face the same detection window. First-time users who are in good physical condition with a good metabolic rate tend to metabolize weed faster.

When using the most common drug tests like urinalysis, saliva test, and blood test, the longest period for detection from the toxicology laboratory would be about 3 days. On the other hand, the hair test has a longer detection window, but this is the least used test as it’s the priciest.


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