Medically Reviewed by
Jason Crawford

Article Last Updated on January 10, 2023

Smoking marijuana remains the preferred method of consumption for many users because it doesn’t take long to feel the effects and the doses are fairly easy to control once you get the hang of it. However, marijuana smokers know that weed stays in the body for a certain length of time and it can be detected in the urine during routine drug screening. 

But, many wonder about how the frequency of marijuana use comes into play and how it affects the detectability of weed in urine. What’s THC’s detection time in urine if you smoke only once in a couple of months? 

Testing for drug use in the workplace has increased so it’s normal to wonder how long weed stays in your system after one smoke session, which is what we cover in today’s article. But before answering the most pressing question, let’s first see how it gets there in the first place.

How Do Traces of Cannabis Even End Up In Your Urine?

Every foreign substance in the body is metabolized in the liver to make it easier to eliminate, which is just how our bodies are wired, and cannabis is no exception. 

When you smoke weed, it reaches your brain in a matter of minutes. This happens so fast because when you inhale and your lungs fill with marijuana smoke, the cannabinoids enter your bloodstream immediately and get carried to the brain where they cross the blood-brain barrier. Next thing you know – you’re high.

THC (tetrahydrocannabinol) is the psychoactive cannabinoid that produces the euphoria, while CBD (cannabidiol) is there to make sure THC doesn’t excite you too much and cause side effects. When we talk about weed staying in urine, we talk about THC and its metabolites because it’s what most drug tests in the workplace look for.

When you get high after smoking weed, the THC concentration in the blood plasma reaches a peak in about 8 minutes. Afterward, as the plasma is being slowly cleared, THC gets sent to the liver to be metabolized. This is when the fun part starts.

What Happens to THC in the Liver, or How it Ends Up in the Urine

The metabolism of THC is one of the more complicated processes that occur in the body. Basically, THC gets metabolized in the liver by a group of liver enzymes that turn THC into byproducts, also called THC metabolites, to make them easier to eliminate from the body.

THC gets converted many times and into over 80 different metabolites, of which the metabolite called THC COOH is the most important one because it’s what most drug tests screen for. 

The body stores the THC metabolites into the fat cells because, just like THC, they are lipid-soluble, meaning that they’re attracted to fat. The metabolites linger there for a prolonged period of time depending on many factors, but over time, they get re-released into the bloodstream and are turned into water-soluble molecules so that they can be easily eliminated through urine (and feces).

How Long Does Weed Stay In Your Urine After One Smoke Session?

The frequency of use plays a major part in how long THC stays in the urine. Chronic users cannot be compared to infrequent users because the former will have more THC metabolites stored in their fatty tissues over time. When you’re a daily user, the body simply doesn’t have enough time to eliminate all of the metabolites because you keep topping up. 

Additionally, cannabis users with a higher body fat percentage or BMI (body mass index) have a greater capacity to store THC metabolites. There are many exceptions to this but it applies to most people.

That being said, the half-life of THC, which is the amount of time it takes for THC to reduce by half, is about 30 hours. This means that every 30 hours, half of the amount of THC metabolites will get eliminated from the body. Therefore, about 80%-90% will get eliminated from the body in about five days, assuming you haven’t smoked weed again.

To make it clearer, if you smoke weed only once in a while, your body should eliminate it completely in 3-5 days, or at least to a level that’s low enough to allow you to pass a drug test. 

Will Smoking Weed Once Make You Fail a Urine Drug Test?

Urine drug tests are the most commonly used in the workplace because they’re non-invasive, accurate, and fast. They’re designed to detect the THC COOH byproducts because they stay in the urine for a long time.

Urine tests have a detection window of up to 30 days, depending on how frequent of a user you are. They detect THC metabolites at a cutoff level of 50 ng/ml (nanograms milliliter), which is the standard threshold for detection. If the THC in your urine is at or below this number, you will not test positive. The urine samples are normally tested twice to avoid false-positive results and any irregularities that may show up.

For comparison, other types of drug tests have different detection times and not all of them look for the metabolites. The hair follicle test is so far the other type of drug test that also screens for metabolites and can detect drug use for up to 90 days. The blood test and saliva test (oral fluid test), on the other hand, have shorter detection times and they look for THC itself.

Can You Speed Up the Detox Process?

The more infrequently you use weed, the easier it is to reduce the time marijuana stays detectable in your body. Since the amount of THC you’re starting with is low anyway, giving your system a little boost can speed the elimination process. But don’t expect a miracle, THC won’t be too easy to eliminate from the fat cells, but you can make it a little easier.

Hydration and staying active are the most important things, and by staying active we mean exercising. Exercising releases the trapped metabolites from the fat cells and speeds up your metabolism, while drinking water will also help to keep your metabolism active and running. Eating clean and ingesting enough protein will also speed up your metabolism. 

To check your progress, there are at-home THC test kits, but their cutoff levels aren’t as sensitive so you might get an inaccurate reading.

The Takeaway

The frequency of cannabis use has a big influence on the amount of time that cannabis will stay in the urine. Heavy users will always have a bigger amount of THC because the body is being saturated with cannabinoids. Infrequent users, on the other hand, will detox much sooner. 

THC gets metabolized into byproducts that get stored in the fatty tissue and get gradually eliminated through urine and feces. In order to avoid getting positive test results during drug testing, the concentration of THC metabolites should be below the cutoff levels.

A passionate advocate for the benefits of cannabis. Fraser Horton, who has a background in botany and a strong love of nature, has spent years researching how cannabis affects the body and mind. He established Leaf Nation in 2020, where he has devoted himself to educating people about the legalisation of marijuana and its safe and responsible use. Fraser is committed to highlighting cannabis’ potential for improving wellness and working to dispel the stigma associated with its use.


The information presented on this page is provided as a public service to aid in education and is derived from sources believed to be reliable. Readers are responsible for making their own assessment of the topics discussed here. In no event shall Leaf Nation be held reliable for any injury, loss or damage that could happen if using or abusing drugs.