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How Long Does Weed (Marijuana) Stay in Your System?

Medically Verified: 2/1/24

Medical Reviewer

Chief Editor

All of the information on this page has been reviewed and verified by a certified addiction professional.

Marijuana is a psychoactive substance that is derived from the cannabis plant. The drug has many nicknames, from weed, pot, and grass to mary jane, bud, and ganja. People smoke, eat, or vaporize marijuana to experience a wide range of effects, including relaxation, increased feelings of happiness, and heightened sensory perception.

According to the CDC, “48.2 million people, or about 18% of Americans, used marijuana at least once in 2019.”[1]

While weed is legal for medicinal and recreational use in some states, it remains illegal on a federal level. Depending on where you live, marijuana might be illegal in your state as well.

A high from marijuana only lasts a couple of hours, but THC, the active compound in marijuana, stays in your system for much longer.

How Does the Body Metabolize Marijuana?

The active substance in cannabis that causes the psychoactive effects is known as tetrahydrocannabinol (THC). When you smoke or ingest marijuana, THC enters your bloodstream. A portion of the THC is temporarily stored in some of your organs and fatty tissues.

However, most of the THC is broken down in your liver. The half-life of THC is about 20 hours, meaning half of the substance is eliminated from your body within this time. It takes somewhere between 5 to 13 days for your body to completely rid itself of marijuana.

Even after the THC is eliminated from your body via urine, the substance leaves behind metabolites. While there are over 100 metabolites of THC, the most prominent ones are 11-OH-THC (11-hydroxy-delta-9-tetrahydrocannabinol) and THCCOOH (11-nor-9-carboxy-delta-9-tetrahydrocannabinol).[2] These metabolites are what drug tests look for to determine whether you have recently smoked, ingested, or vaporized weed.

How Long Is Weed Detectable in Your System?

Because metabolites of tetrahydrocannabinol remain in your system longer than marijuana, drug tests can detect the substance much longer than it takes for your body to metabolize it. It is important to note that everyone’s metabolism works differently, and certain factors like how much weed you consume will affect how long drug tests can detect THC in your body.[3]

The different types of drug tests that can detect weed in your system and their detection windows are as follows.


Urine tests are the most commonly used type of drug test. Detection times for urine testing often depend on how often you were using weed. For single use, marijuana is detectable in your urine for 3 days. If you smoke approximately four times a week, weed is detectable between 5 to 7 days after your last dose.

People who smoke once daily may test positive for THC 10 to 15 days after their last use. Lastly, if you smoke multiple times every day, you will test positive for weed for over 30 days.


Saliva tests have extremely short periods of detection times when it comes to THC. Typically, these tests can only detect marijuana within the same day you last used it, but only for up to 24 hours. As a result, saliva tests are not commonly used to determine whether someone was abusing marijuana.

In areas of the country where recreational marijuana is legal, saliva tests may be used for roadside testing for DUI purposes.


Blood tests typically only detect the occasional use of marijuana for 2 to 12 hours after the person’s last dose. However, among heavy and chronic consumers of weed, blood tests may detect THC in their system for up to 30 days after their last use.


Lastly, hair follicle drug tests have the longest window of detection times for every substance. Concerning marijuana, these tests can detect the substance in your body for up to 90 days after your last use.

What Factors Play a Role in How Long Cannabis Stays in Your System?

Several factors influence how long weed remains in your system. First, personal factors like your body mass index (BMI) and the rate of your metabolism may influence how long it takes your body to eliminate the substance. People with slow metabolisms or a high percentage of body fat may test positive for THC longer than others since THC is stored in fat cells.

Other factors are directly related to weed and how you consume it. For example, how much marijuana you use, how often you use it, the potency of your marijuana, and the method of administration all affect how long it stays in your system. People who use large amounts of potent weed frequently will test positive for the drug longer than occasional users.

Even further, cannabis that is ingested instead of smoked will remain in your body longer.[4]

Get Connected With a Top-Rated Marijuana Detox Center in North Carolina

If you or a loved one frequently abuse marijuana, you could be suffering from weed addiction. Despite popular opinion, you can become addicted to weed. If you attempt to suddenly stop using the drug after a period of dependency, you will experience symptoms of withdrawal.

While marijuana withdrawal symptoms are not life-threatening, they can be extremely difficult to cope with. Attending a medical detox program will ensure that you overcome the withdrawal phase of addiction recovery by providing you with emotional support and medications that limit symptoms of withdrawal.

To learn more about our marijuana detox and treatment program in North Carolina, contact Charlotte Detox Center today.