How Long Does Weed Stay In Your System

Though its calming and healing effects fade relatively quickly, weed remains detectable in your body for prolonged periods. Its main psychoactive component, tetrahydrocannabinol, is notoriously difficult to break down and eliminate, increasing cannabis detection time up to 90 days.

In this research, we’ll study just how long does marijuana stay in your system and what factors affect its accumulation. We’ll also cover how the body eliminates THC and various detection methods that can cause you to fail a drug test. But first, let us get acquainted with THC.

What Is Tetrahydrocannabinol?

More commonly known as THC is one of 113 known cannabinoids found in marijuana plant. It’s the primary psychoactive compound of cannabis responsible for famous “high” the plant provides.

THC Metabolism

When smoked or vaporized,

  • The effects of THC are felt within minutes as it travels into your lungs and then enters the bloodstream.
  • Through your blood, THC binds to CB1 and CB2 receptors located in the brain, central nervous system and other organs.

The process is somewhat different for edible marijuana use. When ingested with oral fluid,

  • THC travels through your digestive tract and enters bloodstream through the walls of intestines.
  • This process can take from 20 minutes up to an hour, depending on absorption and person’s metabolism.

While you’re experiencing the effects of cannabis, THC molecules in your bloodstream are broken down into metabolites by the liver. Most of these metabolites are later excreted through urine and feces. However, not all metabolites get flushed out; some are absorbed by the body and end up stored in your fatty tissues

How Long Does Weed Last?

The effects of cannabis can last for several hours, depending on how a person uses marijuana, and how potent the strain was.

  • In case of smoking or vaping, THC can last three to four hours, sometimes up to 8 hours.
  • Marijuana edibles usually produce more potent effects, which can last up to 24 hours.

Though it provides short-term effects, marijuana stays in your system for a long time. Due to the nature of how body metabolizes THC, drug tests can detect it in person’s system for several days or even months after marijuana use.

Which Factors Affect THC Detection Window?

Cannabinoids like THC and CBD are fat-soluble chemicals1, so they’re easily absorbed into body fat and will stay there until it’s metabolized for energy. This makes it notoriously challenging to detox from marijuana.

As your body burns body fat reserves for energy, THC metabolites will slowly re-enter the bloodstream. They can provide a brief high2 before being filtered out by the kidneys and then flushed through urine. It can take several days, if not months until all residual delta 9-tetrahydrocannabinol is removed.

Frequency Of Use

Cannabis is usually detectable in blood, urine and oral fluid for 1 to 30 days after last drug use, and for several months in hair follicles. This largely depends on how much weed you smoke or ingest, how often, and how potent the herb is. Higher concentrations of THC, along with more frequent cannabis consumption, are usually associated with longer detection times.

  • Light users, or people who take 1-2 hits of weed occasionally, may test positive for 1-3 days after last use.
  • Irregular users, people who smoke 3-4 times a week, usually test positive for 5-7 days after last drug use.
  • Chronic users and people that use marijuana every day may test positive for a month or more.

These detection windows are only rough estimates, which depend on many factors. We’ll cover them later in this research.

Fat vs. Skinny Guy vs. Athlete

As we’ve stated earlier, frequency of use and amount of THC in the strain are two most important factors that affect marijuana detection. But there’s more to this complex equation.

  • A faster metabolic rate means more efficient expulsion of THC from your body.
  • People with higher body mass index retain more delta 9-tetrahydrocannabinol in their fat deposits.
  • Regular exercise increases your metabolism, helping you burn fat and decrease THC levels.

Note that metabolizing body fat during physical exercise releases THC back into the bloodstream, which can trigger positive test result for marijuana.

Type Of Test

In the end, THC test sensitivity also plays a vital role. Drug tests have a cutoff concentration, results above which are considered positive (failed). Different testing methods feature different cutoff values, and more sensitive ones are more likely to detect THC in the body.

How Long Can Drug Tests Detect Marijuana?

Since they’re lipophilic, cannabinoids have a significantly longer elimination half-life compared to other recreational drugs. In addition, detection times depend on what type of drug test you’re taking.

There are eight main testing methods to detect recent use. We’ll describe the most common types of drug testing, along with corresponding length of time during which they can detect positive THC concentrations in your body.

How Long Does Weed Stay in Your Saliva?

Delta 9-tetrahydrocannabinol can enter oral fluid when you’re smoking a joint or consuming edibles. As a result, it can be detected in your saliva for 24 hours after last use, with some high-end saliva tests detecting marijuana for up to 72 hours. This type of test is mainly used for roadside testing in states where weed is legalized.

How Long Does Weed Stay in Your Blood?

Since urine doesn’t show current impairment, blood tests are often used in DUI investigations. Weed appears in blood seconds after inhalation, or approximately 30 minutes after ingestion, and remains detectable for several hours. However, blood test doesn’t show long-term cannabis use and can’t be used to determine the level of intoxication precisely.

How Long Does Weed Stay in Your Urine?

Urine tests are the most common drug testing method, because it provides greater accuracy and longer detection times, compared to blood and saliva tests, while being cheaper than hair tests. Though it only shows recent marijuana use, not the current impairment. You can learn how to pass a urine drug test in our in-depth guide.

Urinalysis usually consists of two separate steps: ELISA test and gas chromatography-mass spectrometry (GC-MS) test.

  • ELISA tests come in the form of testing strips, which can only detect the presence of illicit substances.
  • If urine tests positive on ELISA test, it goes through highly accurate GC/MS testing.
  • First-time cannabis users don’t have enough THC metabolites to trigger standard 50 ng/ml cutoff level.
  • Chronic users, on the other hand, may test positive for several months after last use.

How Long Does Weed Stay in Your Hair?

Hair test provides the longest and most precise detection. THC-COOH, as an organic compound, remains in your hair follicles forever, unless you cut your hair or rinse it out with special hair test detox shampoo.

Lab technicians take approximately 1.5 inches of your hair, which roughly equates to 90 days of growth. Subsequent analysis of hair samples is similar to GC-MS urine test.

Frequently Asked Questions

Can You Fail A Drug Test After One Puff?

Yes, you can fail a saliva drug test from only one puff, since it detects the parent substance in your saliva, rather than its metabolites. One-time users shouldn’t worry about failing blood, hair or urine marijuana tests.

How Long Can One Joint Stay In Your System?

Depending on various factors like your metabolism, BMI and dose, test may detect marijuana from one joint for up to 7 days.

What Can Cause A False Positive For THC In Urine?

Several different allergy products, pain medications, and drugs for infections are known to trigger false positives during ELISA testing. These false positives are then eliminated by GC/MS testing method. Besides, the manufacturers of these tests are continually improving them, reducing the chances of false positives.


There’s no accurate way to predict the amount of time how long marijuana stays in your system. In different cases, weed can stay in your body anywhere from several hours to months after last use. That’s why it’s best to complete a proper THC detox program when preparing for an upcoming drug test.