Medically Reviewed by
Jason Crawford

Article Last Updated on December 22, 2022

Unsurprisingly, this is the most researched topic among cannabis users after being notified that a mandatory workplace drug test is going to take place soon. And the answer isn’t one size fits all as regular users need a longer time to detox compared to occasional users.

In a previous article, we tackled the subject of whether you can pass a drug test when your last use was a week ago as well as the detection times if you’ve smoked weed only once, so take a look at those if you find them useful.

However, if you’re interested in knowing the length of time you’ll need to spend without consuming weed after your last cannabis use to have a negative drug test result, read on. We’ll go over the basic information connected to cannabis consumption and how the body metabolizes cannabis, and dive into the subject of detoxing from weed, so let’s get started.             

How Does Your Body Metabolize Cannabis After Drug Use?

Here’s what happens in your body as a result of recent use of cannabis. After consumption, the two main cannabinoids (THC and CBD), as well as the other cannabinoids and compounds of weed, are absorbed into the bloodstream – after which, they produce the well-known psychoactive, sedative, anti-inflammatory, and other effects on users.

The cannabinoids and cannabinoid metabolites are later broken down in the liver, some of which remain stored in the organs and fatty tissues for a while. Among the 80 metabolites that are broken down in the liver, you can find the two which are most often shown in drug tests: 11-OH-THC (11-hydroxy-delta-9-tetrahydrocannabinol) and THC-COOH (11-nor-9-carboxy-delta-9-tetrahydrocannabinol). 

After a while, the metabolites are further broken down and released through the stool and urine. It’s important to note that each individual’s body will need a different amount of time to get rid of them, but more on this later on. (Sharma et al, 2012)

Types of Drug Tests and THC Detection Times

Drug tests are used to reveal the presence of weed by checking for the presence of weed’s metabolites (weed’s by-products) in the body. The metabolites of the cannabinoids are still present in your body even after the initial effects of cannabis have worn off. The THC metabolite that’s most commonly searched in drug screenings is THC-COOH (11-nor-9-carboxy-delta-9-tetrahydrocannabinol). These are the most common drug tests used in the workplace:

  • Urine test (searches for cannabis and cannabis metabolites through a urine sample);
  • Blood test (searches for cannabis and cannabis metabolites through a blood sample);
  • Saliva test (the oral drug test searches for cannabis and cannabis metabolites through a swab of saliva);
  • Hair test (the hair follicle test searches for cannabis and cannabis metabolites through a hair follicle and has the biggest detection window).

What Can Affect Your Drug Testing Results?

How long weed stays in your system before the body metabolizes it can depend on a few factors. Whether or not you get a positive result on your next cannabis drug test and the amount of time it takes for THC to leave your system will depend on:

  • The method of consumption (smoked weed takes longer to metabolize compared to ingested weed);
  • The amount of THC you consume (the higher the dose, the longer it takes for your body to break down the cannabinoids and their metabolites);
  • The frequency of use (frequent users and chronic users have higher detection rates compared to infrequent users);
  • The body mass index (BMI) and physical activity of the user (since cannabinoids are lipid-soluble and bind to fatty tissues and fat cells in the body, the amount of time that weed can be detected also depends on the amount of body fat users have);
  • Metabolism (bodies with a higher metabolic function will break down the cannabinoids quicker than bodies with lower metabolic functions).

How Long Does Marijuana Stay in Your Blood? 

As we’ve mentioned above, the length of time it takes for your body to metabolize cannabis depends on a few factors. However, different drug tests have different detection times, so the focus of this article is the blood test and how long after marijuana use can THC and its metabolites are detected in the blood.

After you inhale cannabis, the cannabinoids end up in the bloodstream after only a couple of seconds, and the plasma concentration of THC peaks in about 3 to 8 minutes, according to a 2004 review, so you’ll surely get a positive result if you get a blood test that day. The frequency of use and the dose of cannabinoids will affect how long weed stays in your blood, so according to some studies, frequent users can get a positive test for up to 24 hours, while infrequent users will detox in up to 4 hours

However, according to a 2009 study, the THC metabolites can remain for an extended period of time, even a few weeks after the initial cannabis use. This is prolonged even more if the user consumes cannabis on a regular basis.

How Long Can Marijuana Be Detected Through Other Tests?

Apart from testing the blood, marijuana can be detected through a:

  • Urine test (the detection time of urine tests is 72-hours for first-time users, however, chronic users can expect a positive test for as long as one week); 
  • Saliva test (you can expect a positive oral fluid test for up to 3 days as an occasional user, and up to a month as a heavy user);
  • Hair test (the biggest detection window is provided by the hair follicle test which can detect cannabis use for up to 3 months).

The Dangers of Substance Abuse and How to Detox From Cannabis?

Short-term cannabis use can lead to cognitive impairment which means that you won’t be able to drive or operate heavy machinery. Drugged driving is a threat to yourself and others, and if you’re caught, you can get into trouble. If you’re interested in learning how long after smoking weed you can drive, look at our article on the subject.

Long-term marijuana use can lead to marijuana dependency and even mental health problems with users who are battling depression, anxiety, or other conditions, which is why consuming marijuana responsibly is really important.

People who’d like to detox from cannabis for a pending mandatory cannabis test, sometimes use detox kits and drinks to speed up the process like consuming niacin (vitamin B3) to help the body metabolize weed faster, although your best option is to stop using weed altogether and give your body enough time to detox on its own. Eating a healthy diet, hydrating, and quitting weed is your best bet at passing your drug test.

Final Thoughts on How Long Cannabis Stays in the Blood

From all the information provided above, we can conclude that there is no one-answer-fits-all when it comes to giving you a time frame for passing a cannabis blood test. For chronic users, the detection window will be longer and can last up to a day, while newbies and occasional users may have a clean blood test after 4 hours.

However, according to some studies, THC metabolites can sometimes be detected through a blood test for a few weeks after the initial use of cannabis, and if you get a hair follicle test, marijuana use can be detected for up to 3 months.

Your best bet when you have a drug test soon is to eat healthy foods, hydrate your body, and stop using weed. People with a faster metabolism will detox from cannabis faster, so exercising regularly will help your metabolism and your detox process as well.

For more information about marijuana and drug testing, you can visit the official site of Mayo Clinic as well as the National Institute on Drug Abuse site.

Additional Sources

Sharma, P., Murthy, P., & Bharath, M. M. (2012). Chemistry, metabolism, and toxicology of cannabis: clinical implications. Iranian journal of psychiatry, 7(4), 149–156.

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.