How Long Does Marijuana Stay in Your System. The Ultimate Guide

Studies show that drug tests can detect weed metabolites in your blood for up to 7 days after a single marijuana cigarette.

how long does marijuana stay in your system chart

Following a single dose of edibles, marijuana metabolites have been detected for more than 5 weeks in the urine and feces.

Urine drug tests can detect weed for 30 days.

THC can be detected in saliva for three days.

Since marijuana metabolites are highly fat-soluble, they can be stored in body fat for months.

In hair, weed can be detected for up to 3 years ( in case you don’t cut your hair for that long)

Now, we will explain why marijuana stays in your system for so long.

Information source

This article summarizes scientific research on how long does marijuana stay in your system, visualized and explained in simple language.

Read on to know why cannabis stays in your body for so long. And how to get it out of your system faster.

How our body processes marijuana

We will briefly walk you through marijuana metabolism.

Raw cannabis contains tetrahydrocannabinol acid (THCA), which doesn’t cause a “high” effect.

When heated THCA turns into THC (delta-9-THC), which is psychoactive.

Here’s the list of THC and its metabolites and their common names.

When cannabis is smoked or vaporized, THC enters the bloodstream via absorption through the lungs.

When ingested, THC enters the bloodstream through the walls of the stomach and intestines.

THC and its metabolites are highly fat-soluble, so about 70% of THC is absorbed by body fat.

Then THC is slowly released from the fat back into the blood.

Each time the blood circulates through the body, a certain portion of it passes through the liver.

There THC is metabolized in 2 phases and then excreted via urine and feces.

Marijuana metabolism scheme

How Long Does it Take to Feel the Effects and How Long Does it Last?

In an experiment, researchers gave three forms of THC to subjects on ongoing trials.

The trials were separated for at least one week, and the treatments were randomized.

The objects were required to smoke a marijuana cigarette, eat chocolate cookies infused with THC, or make an injection of THC.

The results were the following:


The first noticeable effects were within 5 minutes, and smokers reached the peak “high” at 30 minutes. It took about 4 hours for the effects to wear off.


The first noticeable effects were after 30 minutes. The peak occurred between 2 and 4 hours after consuming edibles.

The degree of “high” was lower, and it took about 6 hours for the effects to wear off.


Patterns were rather similar after both intravenous injections as well as smoking. The first noticeable effects were within 5 minutes, and the peak “high” was reached at 30 minutes.

how long does effects of weed last chart

How Long Does it Take for the Effects to Wear Off?

According to the mentioned research, it took four 4 for effect to wear off after smoking and via injection. The edibles need 8 hours to fade.

There was another study involving pilots who smoked a cannabis cigarette containing 20 mg of THC.

This dose caused a significant reduction in their performance.

The decrease in performance lasted over 24 hours after the single dose. Furthermore, most of the pilots were unaware that their performance was still impaired at 24 hours.

How Long is Weed Detectable by Drug Tests?

As we already mentioned, THC and its metabolites are highly fat-soluble, and they “stick “to body fat and are slowly released into the blood. This process is very slow. That’s why THC takes so long to remove from the body.

According to the research, it takes about seven days to remove half of the THC from the body after a single cigarette. And complete elimination of a single dose may take up to 30 days.

When THC gets into the liver, it is metabolized to 11-OH-THC, THCCOOH, and some other metabolites.

We will tell for how long each of these metabolites stays in your body.

How Long Does Weed Stay in the Blood

In a study of six people, researchers gave them cigarettes with approximately 16 mg and 34 mg of THC. They then tested the subjects’ blood for the concentration of THC and its metabolites. The cutoff level for detection was 0.5ng/ml.

According to this study

THC blood concentrations chart

How long does weed stay in the urine?

Another study involved 60 regular cannabis users. These subjects had to stop using weed during the research. Researchers tested their urine for THCCOOH with a cutoff level of 50ng/ml.

The maximum detection time was 29 days.

One of the group detection rates remained between 60 and 100% for 28 days after the first negative urine test.

That means that even if your results were negative on the urine drug test, you could still test positive after that.

As we can see from this study – the weed can stay in your urine and be detected for up to 30 days and more for heavier uses.

We will tell why this time can increase further in the article.

How long does weed stay in the saliva?

When you smoke or eat edibles, part of the THC stick to the oral cavity and stays there for some time, this is the only source of THC in the saliva because it is not reabsorbed from the blood.

There was research where participants were required to smoke cigarettes containing 14-44 mg of THC. After that, the concentration of THC in saliva was tested.

The peak concentration was within 2 hours and then gradually reduced below one mg/L after ~22 hours.

In another study: participants were required to take capsules containing 5-15 mg of THC.

After that, the concentrations of THC in the oral fluid were deficient, almost not detected.

The cutoff level of saliva drug screening tests depends on the device used. The lowest is 15 ng/ml, which’s 0,015 mg/L.

Unfortunately, there are no studies that last more than 24 hours. Still, according to the data from this study, we can assume that the concentration will drop below the detectable level within 48 hours.

So, summarizing all the information from the studies:

Weed(THC) stays in your saliva and can be detected for up to 48 hours (2 days) after smoking. It may take more time for heavy users.

How long does weed stay in the hair?

Your hair can store weed metabolites in several ways. Deposits can come from the bloodstream, sweat, and even your oil glands.

THC hair deposit routes

Because head hair grows at approximately 1 cm per month, the window of hair analysis detection can range from many months to years.

If we cut the hair into sections (one cm each), it is possible to obtain information on the use pattern. This means we can tell whether there was an increase, decrease, or constant usage of weed.

THC in hair chart

THC enters the hair from tiny blood vessels into growing cells over a length of 1.2 to 1.5mm.

In regularly shampooed hair without any treatment, such as hair colors, bleaching, or permanent wave, THC is well detected for at least one year after intake.

One long hair study found drug presence more than three years after ceased consumption.

This means that your hair can store weed metabolites for many months and years.

Body Fat

We will use THC here as a name for THC and its metabolites, 11-COOH-THC and 11-OH-THC.

As we already mentioned, THC is highly fat-soluble, and about 70% of the THC from the blood is absorbed by body fat tissue.

According to the study, the absorption half-life from the plasma is 50 sec. During the 50 seconds after smoking, 50% of all THC in the blood will be absorbed by the fat tissue.

Then THC is slowly released from the fat into the blood and metabolized by the liver.

The more weed you consume, the more THC is accumulated in the fat and the more time required to release it for excretion.

If your body is not trained to use fat as an energy source, it will not break down the fat cells. So THC can stay in those cells for months.

THC fat distribution chart

Key Factors That Influence How Long Weed Stays in Your System

THC Dose and Frequency of Use

The more you smoke, the more THC gets into your blood and then stored in your body. This means the higher the dosage and frequency of use, the longer it will stay in your body.

Body Fat

Body fat is the primary storage tissue of THC and its metabolites. So the more body fat you have, the more THC will be stored in your body, and your body will require more time to remove it.

Another side of this is that people with more body fat cannot burn their fat faster, and their metabolism rate is low. So their bodies will release THC from the fat very slowly, and it will stay for a longer time.

Metabolism rate

Metabolism is a term used to describe all chemical reactions involved in maintaining the living state of the cells and the organism.

So people with higher metabolism speed will be able to metabolize and remove THC from the body faster.

Body Type

Endomorphs have a higher percentage of body fat. They also tend to burn fat harder than ectomorphs (typical skinny person). So THC will stay in their system for a longer time.


Women usually have more body fat than men. For example, the amount of essential fat for women is ~11%, for men ~3%. Thus women can store more THC, and it will take more time to remove it from the body.

On the other side, research shows that women produce more CYP3A4 enzymes, the main enzymes responsible for phase 2 of THC metabolism. Thus they can metabolize and excrete THC faster.


The study showed that drinking 500 ml of water increased metabolic rate by 30%. The increase occurred within 10 min and reached a maximum after 30-40 min.

Drinking water will increase the metabolism and excretion of THC. Also, drinking more water will make you pee more frequently, and thus you will remove THC metabolites from the bladder faster


Several studies(this and this) confirms that exercising can increase fat cell breakdown and increase the resting metabolic rate.

Thus exercising will increase the release of THC from the fat stores and its elimination after exercise.

It is essential to know that during exercise, the blood flow through the liver decreases. This will result in THC metabolites will be released from the fat into the blood but will not be metabolized during the exercise.

You can experience “flashbacks” during exercise because the levels of THC in the blood will increase.

How Much Do You Have to Smoke to Fail a Drug Test?

In a study, researchers seated six non-smokers in an alternating manner with smokers. Then they collected urine samples of non-smokers.

They analyzed the urine samples for the THC metabolites at different cutoff concentrations (20, 50, 75, and 100 ng/ml).

Urine tests showed a single positive at 50 ng/mL and multiple positives at 20 ng/mL. The maximum THCCOOH concentration for non-smokers was 57.5 ng/mL.

THCCOOH concentrations increased with THC potency, but room ventilation reduced exposure levels.

This study with non-marijuana smokers shows that even if you do not smoke weed, you can still fail a drug test with second-hand smoke.

Smoking even one joint makes you fail a drug test within the next few days.

Symptoms of Marijuana Overdose

You can overdose on marijuana, but it is rare. Here are some of the symptoms that you may experience if you overdose on weed: