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

If you have smoked marijuana, or if you have been exposed to secondhand marijuana smoke, you may be wondering how long marijuana stays in your system.

Marijuana, also commonly known as “weed” or “cannabis,” is one of the most commonly used drugs throughout the world. The main chemical in marijuana is tetrahydrocannabinol, also known as THC. Although the effects of THC wear off within a few hours of ingesting marijuana, traces of the chemical can remain in the body for weeks. In turn, the length of time in which THC can stay in your system depends on the drug testing method and ranges between:

• 30-45 days can fail a urine test
• 60-75 days can fail a blood test
• Up to 90 days can fail a hair follicle test

Marijuana Showing Up on Drug Tests

The non-THC components of marijuana itself do not stay in the body long periods of time, which is why hemp and other marijuana-based products will not cause you to fail a drug test for marijuana. However, most drug tests are designed to detect THC specifically. 80%-90% of the total dose of THC is usually excreted within the first week, however, the remaining 10%-20% can linger for much longer. The testing method used will ultimately dictate how long THC can be detected in one’s system.

Marijuana Detection in Urine Tests:

Testing urine is one of the most common methods for determining marijuana use. Most urine tests can detect marijuana several days after you have last had it. However, if you are a heavy marijuana user, marijuana may still show up in your urine even after several weeks.

Marijuana Detection in Hair Tests:

Hair strands can pick up THC in several ways. Like a urine test, testing hair strands can detect traces of THC in the body after they pass from the bloodstream to the hair follicle. But it can also get into the hair from physical contact, meaning that you do not necessarily need to be taking marijuana to have your hair test positive for it. If you have been around secondhand marijuana smoke, have touched marijuana or even if someone who has handled marijuana touches your hair, your hair may test positive. The hair test can be positive for up to 90 days after exposure.

Marijuana Detection in Blood Tests:

When it comes to testing for marijuana use, blood tests are not often used. This is because blood tests have a narrow window of time to detect marijuana use. These tests typically only work within three to four hours when a person uses marijuana, which is when THC is still in the bloodstream.

Marijuana Detection in Saliva Tests:

Similar to blood tests, most saliva tests can only detect marijuana within 24 hours of use.

Marijuana and Breast Milk:

Marijuana can get into your breast milk. Doctors think it is dangerous for a nursing baby to be exposed to breast milk after the mother has had marijuana. Babies exposed to marijuana may even test positive for it in their urine, and may have symptoms like poor muscle tone.

Factors that Affect How Long Marijuana Stays in Your System

There is no way to know exactly how long THC will stay in someone’s system for a drug test. However, there are different factors however that can impact how long marijuana stays in the body.

Frequency of Marijuana Use:

Someone who has been using marijuana regularly is likely to have a buildup of THC in their system, meaning it will take longer to leave the body.

Concentration Levels of THC:

Marijuana can have varying levels of THC. If marijuana with a higher THC potency is used, the chemical traces will remain in the body for longer periods of time.

Method of Marijuana Use:

How marijuana is used can have a significant impact on the amount of time it is detectable. If marijuana is smoked, the THC levels in the body will drop within a few hours or days after use. But if it is ingested, the chemicals are broken down more slowly and may remain detectable longer.

Marijuana and Weight:

THC is stored in the body’s fatty tissue. Those with less fat in their body will clear their system of THC faster than those who have more fat. Someone who eats well, exercises and gets enough sleep has a body that will function better, meaning it will get rid of THC at a faster rate than someone who is in poor overall health. However, doing a lot of exercises right before a marijuana test can increase the concentration of THC. This is because THC is stored in fat, and if you exercise and that fat breaks down, THC is released back into your system. Each and every person who smokes marijuana has a rate of metabolism that is completely different and this can dramatically alter the way the human body breaks down THC, which can very easily change how many days marijuana will stay in the person’s system or cause a failed drug test.

Other Drugs:

Certain drugs can affect how fast your body is able to remove THC. This is because they may alter the concentration of THC in your body. Drugs that can increase THC levels include:

• Ketoconazole
• Clarithromycin
• Erythromycin
• Cyclosporine
• Verapamil
• Itraconazole
• Voriconazole
• Boceprevir

Other drugs, like rifampin, may decrease the amount of THC in your body. In addition, THC itself can impact other drugs. THC can increase the effect of warfarin in your body. THC can also decrease the effect of theophylline and chlorpromazine.

If you or a loved one struggle with marijuana addiction, our trained professionals at The Recovery Village can help. The Recovery Village offers many different addiction treatment options to help you lead a healthier life. Reach out to us today for more information.

Editor – Nicole LaNeve

Nicole leads a team of passionate, experienced writers, editors and other contributors to create and share accurate, trustworthy information about drug and alcohol addiction, treatment and recovery for The Recovery Village and all Advanced Recovery Systems sites. Read more

Medically Reviewed By – Dr. Jessica Pyhtila, PharmD

Dr. Jessica Pyhtila is a Clinical Pharmacy Specialist based in Baltimore, Maryland with practice sites in inpatient palliative care and outpatient primary care at the Department of Veteran Affairs. Read more