How Long Does THC Stay In Your System?

Trying to get a job or pass a test?

Watering a cannabis plant in a pot with a squirt bottle

Cannabis has a relatively long half-life compared to other illicit drugs that are classified as Schedule 1 controlled substances such as heroin, ecstasy, LSD. THC can stay in your system for up to 30 days with a urine test. This guide will walk you through all the things you need to know about how long weed stays in your system and how drug tests work to detect them.

How Long Does Cannabis Stay In Your System?

This question is tough to answer since it varies so much from person to person, but we can help you get a general idea of how long those THC-COOH molecules will be hanging out in your body.

Urine Tests

If you’re getting a drug test, it’s most likely that they’ll be testing your urine. For consistent use, marijuana can be detected in urine for more than 30 days after your last smoke, but a light or casual user will most likely not test positive after a full month of abstaining. Someone who only smokes marijuana every once in a while has a good chance of passing the test after only 3-7 days. Heavier users should give themselves a little bit more of a buffer zone between their last smoke session and their urine test.

Blood Test

It’s rare that a blood test will be used to see if you’ve been smoking, because they aren’t able to detect THC in as long of a window as urine tests. Blood tests would be used in the context of proving acute impairment. For example, if you’re suspected of a dui or workplace impairment, or if you suffered an on the job accident, a blood test may be conducted. THC assimilates into adipose tissue (fat) not the bloodstream, so these tests will typically only detect marijuana within 3-12 hours of use if you smoked a strain with a low concentration of THC. However, if you smoked a high potency strain (>3%, so basically almost every non-CBD dominant strain nowadays) the window shifts to about 6-27 hours. However, typically the cutoff for acute impairment would be >5ng/mL detected within a 3-4 hour window.

blood probe and request formular for analysis

iStock / mbz-photodesign

Saliva Test

Like blood tests, these will be rare and you won’t have to worry too much about passing as clean when it comes to marijuana. Saliva tests will only detect marijuana within about 24 hours of use. However, if you’re a frequent smoker, that window could be longer than 30 hours.

Hair Test

Hair test can be tricky, since you don’t necessarily need to use marijuana for it to get in the hair follicle. Whether you’re an actual smoker or secondhand smoke just made contact with your hair, you can test positive up to 90 days after you’re exposed to it.  Hair analysis can be used as a qualitative indicator of heavy cannabis consumption within the past 3 months but cannot reliably show light consumption or quantity. Furthermore, it is thought to be detectable for the life of the hair but 90 days is typically quoted because a 1.5inch hair sample is typically tested, which is thought to grow in 90 days.

How Do Drug Tests Detect Cannabis?

Whether you’re taking a urine, blood, hair, or saliva test, they’re all looking for one thing—tetrahydrocannabinol, which in regulatory papers, court briefings, as well as legal documents, can be referred to as THC Acid, THC, THC carboxy or 11-COOH-THC. Although the precursor/metabolite also has carbon, the carboxyl is attached to 2 vs 11. More commonly known as THC, this cannabinoid is the psychoactive ingredient in marijuana that makes the plant so popular. It’s a lipid-soluble chemical, so it binds to the fats within the users’ body, making it harder to flush out.

The nomenclature in drug testing is confusing. The primary psychoactive agent is THC. The naturally occurring precursor is tetrahydrocannabinolic acid (aka THC acid, THCa, THC carboxy, or 2-COOH-THC) [carboxyl group in the inactive precursor is on carbon 2#] Heat and drying will decarboxylate the inactive cannabinoid thus forming THC.
However, the primary metabolite of THC (target analyte for urine tests) also contains a carboxyl group through glucorindation, but on carbon 11#]. Thus in regulatory papers, court briefings, legal documents etc. it is also called THC Acid, or THC, or THC carboxy or 11-COOH-THC. I’d suggest to avoid confusion to use precursor/metabolite or which carbon the carboxyl is attached to 2 vs 11.
-Dr. Baran Erdik, Wikileaf Medical Expert

Though drug tests are trying to decipher whether your body has processed THC or not, it doesn’t do so by just finding leftover THC in the body. Instead, they look for THC metabolite (THC-COOH), which the body uses to breakdown THC. The metabolite is also lipid soluble and takes even longer to leave the body than just plain ol’ THC, allowing drug tests to detect it for many days or even weeks after use.

How Do I Get THC Metabolites Out of My System Faster?

Finding out you have to take a drug test is never fun, but you don’t need to panic. Taking a little time away from bud is the best way to ensure a clean test and eliminate anxiety leading up to it, but there are a few other factors that you can address to help make sure you come out clean.

Frequency of use is the biggest factor, but body fat is also extremely influential when it comes to your body’s ability to retain or release THC from your system. It’s a common misconception that if you exercise, you’re more likely to pass a drug test. The thought process is that exercise breaks down fat cells more rapidly, making it more difficult for your body to store THC. Unfortunately, in the short term before an upcoming drug test, exercise is potentially one of the last things you want to do, as it’s more likely to cause you to fail. The more fat you break down, the more THC you’re releasing into your blood stream.  Keeping a consistently healthy diet (not just trying to work out when you have a drug test coming up)  is the best way to reduce the amount of THC that your body holds onto. If you have a naturally fast metabolism, that can also work in your favor when trying to pass a urine test.

When it comes to finding a fast solution to an impending drug test, many people also swear by cranberry juice, which is a natural diuretic and anti-oxidant. Some claim that this allows cranberry juice to “flush out” the metabolites from your system, but there’s no scientific proof to back that claim up. While cranberry juice is a natural diuretic, the real issue is the rerelease of THC to the blood from adipose tissue, not the excretion of THC in urine, so theoretically cranberry juice might actually be useless. One could possibly make the argument that urine alkalization could help with passing the test, but again, the limiting issue is not excretion in urine, but rerelease into the blood. Logic aside, since there’s no scientific proof to back cranberry juice’s effectiveness, we’d recommend taking that with a grain of salt.  There’s no harm in using this method to assist you in your journey towards ridding your system of THC-COOH, but abstaining from smoking for as long as you can is the only way to truly ensure a passing grade.

Does It Matter What Strains I Smoke?

If you tend to smoke weed with higher levels of THC it may be harder to eliminate it from your body by the time you take your drug test because you’re taking in more THC every time you smoke. If you know that a drug test is always a possibility at your work but don’t want to give up marijuana completely, choosing strains that have a higher concentration of CBD and lower concentration of THC are going to be your best option.

The way you intake weed will also affect how long it stays in your system. When you ingest marijuana through edibles, the metabolites stay in your body longer because bioavailability is higher when you eat your cannabis, so your body is absorbing more of it. Smoking, on the other hand, causes pyrolysis which eliminates some THC before it’s even absorbed. Smoking lets THC be absorbed quicker than edibles and allows peak levels to be achieved faster, but bioavailability is lower so you THC levels will drop significantly faster than if you eat an edible.

Final Thoughts

You can spend hours on the internet researching different ways to pass a drug test—drinking beaucoup amounts of water, chugging cranberry juice, smoking strains with lower THC concentration—but the only surefire way to pass is to abstain from the drug altogether for a while. Not consuming THC will ensure that your body is able to fully eliminate any THC-COOH.

How Long Does THC Stay In Your System? was last modified: by