While most substances in the body vanish within a few hours, tetrahydrocannabinol, better known as THC, can last in various parts of the body for longer amounts of time. Marijuana, often referred to as weed, pot, or cannabis, contains THC, the primary psychoactive compound responsible for its effects.
Whether it’s prescribed or used recreationally, it’s ideal to know how long it remains in the system, to make informed choices and avoid driving under the influence. This article will provide a deeper dive into the question: “How long does THC stay in your system?”
It’s important to understand the risks of driving under the influence. Learn more about drugged driving and how MADD is working to prevent it.
How Long Does Marijuana Stay in Your System?
There is no universal answer to the question of how long weed stays in your system. In order to get an accurate answer, it is best to explore how THC remains in each part of the body. While the information below outlines how long THC stays in each part of your system, it’s important to keep in mind that results can vary significantly from one person to another.
|
Test Type |
Average Detection Window |
|
Blood |
Up to 12 hours |
|
Saliva |
24-72 hours |
|
Urine |
Up to 30 days |
| Hair |
Up to 90 days |
How Long Does Weed Stay in Your Blood?
Weed that is inhaled rather than ingested will enter the organs and bloodstream much more swiftly. Once it enters these areas, it will remain in the body for up to twelve hours. Of all the other places that THC sticks to in the body, this one has the shortest window of time. Since the time that it remains in the bloodstream is brief, marijuana blood tests are typically given in time-sensitive situations, like DUI cases, rather than routine testing.
How Long Does THC Stay in Saliva?
Drug tests for THC in the saliva can detect it for up to 72 hours after use for chronic or heavy users. For light users, marijuana can be detected in the saliva for 24 to 48 hours. These drug tests are typically conducted in roadside or workplace screenings due to their short detection window. Hydration levels may affect the ability of THC to be detected in the saliva.
How Long Does Weed Stay in Your Urine?
THC can last in urine for up to 30 days, with light users having positive test results for up to seven days and heavy users having positive test results for the full 30 days. This is one of the most common ways to test for remnants of this drug in the system. Instead of focusing on the active THC, urine tests focus on THC-COOH metabolites.
How Long Does THC Stay in Your Hair?
Of all the places that THC can show up in the body, it lasts the longest in the hair. It can remain in the hair for up to 90 days (three months). Follicles of hair may be removed from any part of the body to test for THC. Such tests are typically used to detect long-term use rather than temporary intoxication.
THC isn’t the only substance that can remain detectable in the system for extended periods. Find out how long alcohol remains in the body.
How Your Body Processes THC
Whether inhaled or ingested, THC enters the bloodstream and travels to the liver. Once there, the liver metabolizes THC into compounds like 11-OH-THC. Because THC is lipophilic (fat-soluble), it moves through the bloodstream quickly and binds to tissues and organs, particularly to fat stores.
This fat storage plays a major role in how long THC stays in the system. Even after the effects have worn off, THC can be slowly released from fat cells back into the bloodstream over time, leading to extended detection windows.
Factors That Influence THC Metabolism
Not everyone metabolizes THC the same. Although guidelines suggest typical detection windows, these timelines are not universal. Various factors affect how THC is metabolized. Here are several influencing factors that may vary from person to person.
- Method of consumption – How cannabis is used (smoking, vaping, edibles, etc.) affects how THC is absorbed and metabolized. Smoking or vaping delivers THC quickly, while edibles take longer to process and may stay in the body longer.
- Body composition – THC is stored in fat cells, so individuals with higher body fat may retain THC longer than those with leaner body composition.
- Metabolic rate – People with faster metabolisms may break down and eliminate THC more quickly, while slower metabolisms can cause THC to stay in the body longer.
- Frequency of use – Frequent or heavy cannabis use leads to THC building up in the body over time, which can extend how long it remains detectable.
- Hydration and diet – Overall health, diet, and liver function can affect how efficiently the body processes and removes THC metabolites.
- Genetics – Genetic differences can influence how the body processes cannabinoids, including how quickly THC is broken down and cleared from the system.
How THC Affects the Body
When THC enters the bloodstream, dopamine is released, creating what is known as a feeling of being “high.” This release may alter sensory perception, memory, and coordination.
Physically, THC may increase the heart rate, cause a phenomenon known as “cotton mouth,” and may also cause blood vessels in the eyes to expand. In the short-term, marijuana can induce relaxation, and in the long term, it can lead to anxiety or cause impaired motor skills.
Because THC impairs coordination and reaction time, it’s critical not to drive after use. For a safe and responsible way home, explore MADD’s Safe Ride resources.
When Do the Effects of Marijuana Wear Off
Although marijuana may last for hours or months in the body, the physical effects aren’t long-term. After inhaling marijuana, the effects may be felt for up to three hours. Marijuana edibles may last in the body for substantially longer, up to 12 hours. The “high” may dissipate as marijuana leaves the system. However, the grogginess of marijuana may last longer than half a day.
How to Get Weed Out of Your System
While there may be plenty of advice available out there on how to quickly detox weed out of the body, the only surefire method is time. Eventually, the liver will metabolize the stored THC. Simply staying hydrated, exercising, and eating fiber-rich foods will help.
When is it Safe to Drive After Using Marijuana?
The short answer: it’s not. Like alcohol, marijuana can cause impairment, especially while driving. It affects coordination, reaction time, and spatial perception. Therefore, it is best to wait until all effects have completely worn off to avoid unsafe driving. This can take at least 5-7 hours for inhaled cannabis. Waiting also avoids a DUI, as some states have per se laws with specific blood limits of 5 ng/mL, while others have a strict zero-tolerance policy.
Prevent Impaired Driving with MADD
Although the psychoactive effects of marijuana may be fleeting, the physical effects, both short-and long-term, may remain long after the high is gone. There are numerous ways to detect marijuana in the system, and each test yields different results. While someone may successfully pass a blood test, a hair test may detect marijuana in the body long after it’s been used. Using marijuana responsibly and staying away from driving or operating machinery while impaired is critical to preventing DUIs and avoiding serious injuries. Connect with MADD today to get involved in the fight against driving under the influence.
