Medically Reviewed by
Jason Crawford

Article Last Updated on December 24, 2022

Smoking weed is enjoyable until you hear a drug test is being scheduled at your workplace, which is one of the downsides of weed still being federally illegal. This gives employers a green pass to screen their employees for drug use, including cannabis use, and it has become a common practice at workplaces and a prerequisite for job applications.

If you’re a weed smoker who enjoys a doobie here and there or you regularly smoke weed for medical reasons, you might be wondering how to pass the drug test and avoid getting positive test results. Therefore, in this article, we’ll talk about how long weed stays in your body after smoking, the types of drug tests, and some FAQs you might find useful.

Please note that this post is purely for informational purposes only. We are not recommending cheating on drug tests.

What You Need to Know About How Long Weed Stays In Your Body After Smoking

Marijuana stays in your body for a long time after its effects have dissipated, which is why it can be easily picked up by drug tests even days after last use. However, how long it stays depends on a lot of variables that may or may not be in your control. 

Let’s see what factors can determine how long weed will remain detectable:

  • To start with, your frequency of use will greatly influence the amount of time weed stays in your body. If you smoke marijuana frequently, then it will remain detectable for a longer period of time compared to someone who’s an occasional smoker;
  • The potency of the marijuana strain you use also plays a part – more potent strains tend to stay longer in the body;
  • Your unique metabolism also plays a large part. Each cannabis user’s body reacts to weed differently, and this includes its elimination. Some smokers’ bodies can get rid of weed faster than others;
  • Finally, your BMI (body mass index) is also important because it’s believed that people with a higher BMI will store weed for longer periods of time.

It’s Actually All THC’s Doing

When we say weed stays in your body, it’s actually THC that stays. As you already know, THC (tetrahydrocannabinol) is the psychoactive cannabinoid that gets you high

THC (and all other cannabinoids, for that matter) is lipid-soluble, which means it attaches to fat. When you smoke weed, your body metabolizes THC to make it easier to eliminate and turns it into byproducts also known as metabolites. These metabolites are also lipid-soluble and get stored in the fatty tissues of your body before they get gradually eliminated through urine and feces.

Your body metabolizes THC into over 80 different metabolites, but the metabolite called THC-COOH is the most stubborn one that remains in your fat cells for a longer period of time. Therefore, most drug tests look for this metabolite as a confirmation for cannabis use. The more frequent marijuana user you are, the bigger amount of THC metabolites you accumulate. Similarly, if your favorite weed strain has higher THC levels, it will also result in more metabolites.

Types of Drug Testing Methods

There are currently four main drug testing methods, also called immunoassays: urine tests, oral fluid tests, blood tests, and hair tests. All tests are accurate and reliable, and they’re used to discover either recent or habitual drug use. They all have different detection windows, meaning the length of time a drug can be detected in a biological sample.

Drug tests are designed to detect either THC (the parent drug) or THC-COOH at or above a certain concentration, also called cutoff levels. If the concentration of THC or THC-COOH is at or above this level, the test will indicate positive results. If the concentration is below, it will indicate a negative result and you will pass the test. The samples are usually tested twice in order to avoid false-positive results.

Since drug tests only detect THC and its metabolites, users who take CBD oil shouldn’t be concerned with failing a drug test since CBD oil only contains trace amounts of THC that are not enough to cause a big metabolite buildup.

The Urine Test

The urine drug test is currently the most commonly used test in the workplace. It’s fast, affordable, non-invasive, and accurate, which makes it appealing to use as a drug screening method. The urine test detects the metabolite THC-COOH and it can detect habitual drug use from 3 up to 30 days, depending on the frequency of use. 

If you smoke weed infrequently, then the THC should clear in about a week after your last use, whereas for heavy users the detection time is about 30 days after last use.

According to the Substance Abuse and Mental Health Services Administration (SAMHSA) guidelines, the cutoff level for urine tests is 50 ng/ml (nanograms per milliliter).

The Oral Fluid Test

The oral fluid test is done by taking a sample of your saliva. It has a short detection window of up to 72 hours, depending on how much you smoked and what your frequency of marijuana use is. Unlike the urine test, the oral fluid test doesn’t screen for THC metabolites, but for THC (the parent drug) itself. The oral fluid test is sometimes used in the workplace and it’s used to detect recent drug use.

The Blood Test

The blood test also has a short detection time because THC clears from blood plasma rather quickly. Depending on how much weed you smoked it can be anywhere between 2 to 24 hours. Similar to the oral fluid test, the blood test also looks for the parent drug and is most commonly used to detect very recent use or current impairment.

The Hair Follicle Test

The hair test has the longest detection time among all drug tests of up to 90 days. Like the urine test, it’s designed to detect the THC-COOH metabolite in the hair strands because the metabolite is naturally deposited there as the hair grows. The hair test isn’t very commonly used, but it’s considered to be the most accurate and the hardest to pass, especially if you’re a chronic user.


Does Doing a Detox Increase My Chances of Passing the Drug Screen?

Doing a detox is the safest and most ethical way to pass a drug test. It involves immediately ceasing your cannabis consumption and focusing on eating clean. Some put a lot of emphasis on drinking a lot of water, and while this is important, it’s not the main way to detox as THC isn’t water-soluble. Instead, focus on eating whole foods and drinking fresh juices while avoiding processed foods. 

You can also try detox kits that contain ingredients that are supposed to help you detox faster. These may or may not work, depending on your body, but if your timeframe allows it, the natural way to detox is always the best way.

Does Exercise Help With Getting Rid of THC?

Since the THC metabolites reside in the fat cells in your body, exercising will encourage the release of the trapped metabolites. Doing any kind of exercise that makes you sweat can be beneficial, but it’s not a foolproof method to passing a drug test.

Also, bear in mind that since exercising encourages their elimination, their levels will be higher. Therefore, you should avoid exercising at least two days before the test to give your body enough time to cool down.

Do Saunas Help With Detoxification?

Similarly, saunas can help with the detox process because they increase sweating, which helps to release the THC metabolites that linger in your body fat. However, it’s not the only solution because everyone’s body is different, and many other variables are involved. It’s worth trying, though, especially if you enjoy saunas.

Can I Use a Home Drug Test Kit to Check On My Progress?

Home drug test kits are great for checking on your progress or at least to see where you are. They are usually more or less correct, provided that you follow the instructions correctly and don’t let any external factors influence the urine sample, like temperature and waiting time. The only trick with home drug test kits is that some of them may have higher cutoff levels and give you a misleading result. 

Conclusion – So, How Long After Smoking Weed Can I Pass the Test?

Weed tends to linger in the body for weeks after use and it’s all because of the way THC is metabolized in the body. THC is a lipid-soluble compound, which is why when it gets metabolized the byproducts attach to the fatty tissues in the body and stay there as they’re being gradually eliminated.

There are four types of drug tests that detect the presence of THC of which the urine test is the most commonly used. Depending on different factors like frequency of use, the potency of the weed strain, and your unique metabolism, THC can be detected in your body from 3 days to up to 90 days, depending on the drug test used and the previously-mentioned factors.

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.