Marijuana is a medicinal plant belonging to the Cannabis family. It contains a psychotropic component called tetrahydrocannabinol (THC) that has powerful intoxicating effects. The leaves, seeds, stems, or roots are typically used for intoxication purposes. Marijuana cigarettes, joints, and water pipes (bongs) are all used to smoke marijuana preparations. Marijuana is the most abused drug in the United States, with around 11.8 million young adults using it in 2018.
How do drug tests for THC work?
Employers conduct about 40 to 50 million drug tests on employees each year, which analyze biological components such as urine, hair, blood, saliva, breath, sweat, and even fingernails. THC levels rise in the body for a time after cannabis use when it is consumed. Despite falling considerably after a few days, there are still other ways of determining recent usage.
THC, CBD, and their metabolic by-products, called metabolites (also known as endocannabinoids), are lipid soluble and accumulate in fat reserves throughout the body. These chemicals are then slowly eliminated over time, resulting in a longer period for the body to eliminate marijuana traces than with other recreational drugs, especially chronic users. Hair testing has the longest detection window of any type of drug test; it may detect levels of THC-COOH up to 90 days after stopping use.
Urine tests, on the other hand, are the most common drug test and are also the only one specified by SAMHSA, a branch of the U.S. department of Health and Human Services that establishes testing standards for government employees. These urine screens do not directly measure THC concentration, but rather THC-COOH levels. They do not assess the amount of THC present in your system; instead, they look for a metabolite called THC-COOH.
Once a test has been chosen, the experimenter must then select its sensitivity, or the concentration of THC-COOH above which a test is considered positive. The most common cutoff for marijuana urine tests is 50 ng/mL, although cutoffs as low as 15ng/mL and as high as 100ng/mL exist—each resulting in a very distinct detection window.
“Testing is generally a two-step process,” says Vandrey. “The first step is a qualitative yes/no test with a typical cutoff of 50 nanograms per milliliter. And if you discover a qualitative positive, you can send it for confirmation with a more sensitive quantitative assessment that uses a 15 nanograms per milliliter cut-off if necessary.”
Despite the fact that SAMHSA establishes criteria for these urine tests, there is a lot of variance in cannabis use, as well as personal variations in biology and genetics, which makes it difficult to establish distinct time frames for detection.
You’ve probably asked yourself how long marijuana stays in your system whether you’re concerned about an impending drug test or just want to learn more about the effects of cannabis on your body. Not only will this data assist you avoid the negative consequences of testing positive, but it will also help you decide if you wish to use cannabis. So, how long does marijuana stay in one’s system?
For most people, marijuana stays in their bodies long enough to be detected for no more than a month and sometimes only 10 days. However, varying detection periods are influenced by how long you have used the drug and the type of test you take.
The most common detection methods include:
· Urine Tests
A urine test can detect cannabis use for less than a week if you’ve only used it once. Detection times may range from a week to 100 days, but they are usually below 30.
· Blood Tests
Blood tests, which are typically more brief than urine analyses, may find cannabis in frequent users as late as 2 to 7 days after their last usage. These tests are usually accurate for 24 hours if you have only used it once.
· Hair Tests
For one user, this approach is not very helpful because it only alerts authorities when the user uses cannabis again. However, for repeat users, it can detect cannabis usage for months or even years afterwards – especially if they are heavy users.
· Saliva Tests
These examinations have not yet been proven to work with repeated or single users.
Different detection procedures have varying detection periods since they are looking for something different. Urine tests, for example, identify THC-COOH, which is non-psychoactive, while blood tests seek for the psychoactive form of THC. This explains why blood testing is superior at detecting real impairment.
These are the typical detection times for THC, but they may not apply to you as an individual. Users who consume large amounts of cannabis on a daily basis, for example, might have a longer time frame until THC is eliminated from their body. As a result, it’s crucial to consider the following details before making your decision.
Factors for Finding Cannabis
The length of time cannabis stays in your system and your likelihood of testing positive both depend on a wide variety of factors. These include:
· Body Fat Content
The body fat stores cannabinoids, or chemical substances that produce the effects of cannabis on the brain. As a result, the more cannabinoid molecules you have in your system, the longer it will stay there. This implies that individuals with higher BMIs (body mass indexes) will retain cannabis in their bodies for longer. BMI is not, however, entirely linked to overall body fat content.
When you exercise, your body releases chemicals previously stored in fat cells into your circulation. As a result, if you exercise shortly before taking a drug test, you are more likely to be positive. However, exercising weeks before an exam is ideal because it will help burn fat cells that contain cannabis.
When you are dehydrated, your urine or blood will have less water in it, which means cannabinoids will take up a greater proportion of the sample. This technically does not make it stay in your system longer, but it may lead to you testing positive later than you otherwise would because of this.
· Drug Strength
Cannabis plants come in a variety of potencies, with some having more THC than others. The greater the amount of THC present, the stronger the cannabis is. This can cause more cannabinoids to be stored in your body, which may take longer to eliminate.
The rate at which your body eliminates cannabis is determined by your metabolism. It also has an influence on how much body fat you have, which influences THC detection.
· Other Factors
Height, age, gender, and the method you used to ingest cannabis all affect how long it can be detected in your system.
Many individuals believe they may decrease their chance of testing positive for cannabis use based on this data. While reducing body fat and staying fully hydrated can aid your chances, immediate fixes have a poor track record of assisting people pass drug tests.
How long does weed stay in your system?
Meanwhile, each of us has a unique metabolism that processes marijuana at a different rate, further complicating the picture. Even amongst people of the same gender and age, individual lifestyle choices such as levels of exercise and eating habits may also affect the amount of time required to pass a drug test (those with higher levels of fat content store cannabinoids more readily than leaner folks).
After you use marijuana, your body has to break down THC, the active ingredient. THC gets into the bloodstream and is temporarily stored in fat and organs, according to Healthline. Long after you come down from your high, the liver has to process the THC and break it into metabolites, which is what drug tests detect. Because THC binds to fat, it takes longer for traces of marijuana to leave the body than other drugs such as alcohol.
This is how long THC metabolites can be detected in different parts of the body, according to Medical News Today:
- Blood: 3-4 hours
- Saliva: 1-3 days
- Urine: 3-30 days
- Hair: Up to 90 days
The exact amount of time it takes for marijuana to leave your system varies from person to person. Age, sex, and BMI all affect how fast you can metabolize THC. Chronic use, higher doses, more potent strains, and eating edibles rather than smoking marijuana can all increase the length of time it’s detectable in your body.
Given these preliminary grains of salt, however, there are several studies that have explored this question over the years, which offer some general guidance for those awaiting their impending drug test.
According to a 2005 review by Paul Cary, director of the Toxicology and Drug Monitoring Laboratory at University of Missouri, while detection times in excess of 30 days do occur for some, they are largely an exception.
For example, a 1989 study of chronic users showed a maximum detection window of 25 days at a sensitivity of 20 ng/mL. Yet he points out that only one subject tested positive after 14 days, and it took an average of just 9.8 days before cannabinoid levels were no longer detectable. And while a 1984 study testing chronic users at a cutoff of 50 ng/mL showed a maximum of 40 days to get clean, 8 out of the 10 subjects needed only 13 days to show their first negative.
Consequently, Cary offers some shorter estimates of detection windows that he believes would be reasonable to expect given an individual’s frequency of usage and the sensitivity of the particular urine test.
At the standard 50 ng/mL cutoff, he states that “it would be unlikely for a chronic user to produce a positive urine drug test result for longer than 10 days after the last smoking episode.” And if this sensitivity is dropped to the 20 ng/mL level, he posits that this detection window extends to around 21 days for frequent users.
Meanwhile, for those who smoke marijuana occasionally or for the first time, “it would be unusual for the detection of cannabinoids in urine to extend beyond 3-4 days following the smoking episode” at the 50 ng/mL cutoff. This is drawn out to around one week for a more sensitive 20 ng/mL threshold.
It’s also important to remember that “occasional” and “chronic” cannabis users each represent opposite sides of the usage spectrum, and most consumers would likely fall somewhere in the middle.
“I think these [detection times] are reasonable,” says Ron Flegel, director of the division of workplace programs at SAMHSA. “If it is an infrequent use or a single use it usually takes just about 72 hours” at the 50 ng/mL cutoff, whereas “chronic users are probably looking at seven to ten days.”
How long does weed stay in your hair and blood?
Although urinalysis is the most common way to test for cannabis, some drug tests measure the presence of THC in your hair or blood. So how long is THC detectable in your hair and blood?
- Hair testing offers the widest detection window—up to 90 days after you quit using cannabis.
- Cannabis can be found in blood seconds after smoking, and can be detected for hours or even as long as a day afterward.
Factors that may impact drug test results
There are several factors that impact how long cannabis stays in your system. These factors include:
- How often you consume marijuana
- The quantity of marijuana consumed
- How much body fat you have
- The sensitivity of your drug test
Flegel also notes that he often sees cases where individuals fluctuate between positive and negative tests for marijuana over a period of time.
“A lot of people call us and say the person was negative and now they are positive, and they say they haven’t used,” says Flegel. “But if a person becomes dehydrated it concentrates the urine and when they exercise it breaks down fat cells and releases THC,” both of which increase the chances of a positive test. “So you will actually see that over time they will go up and down between positive and negative.”
Meanwhile, Vandrey believes that even these general recommendations are unfounded, particularly for chronic users.
“In a single acute use for a particular dose, we might observe a spread of days,” he explains. “So someone may be clean the next day and others may be positive for seven days. And if you’re talking about constant repeated usage, the variation increases dramatically. I’ve had individuals who smoked cannabis every day throughout the entire day be clean in a week and a half, while others were dirty for two months.”
Many people, for example, try to clean their systems with water just before they’re tested; this has little effect at best, and is particularly ineffective in a short period. The most dependable method to avoid positive outcomes is to stop using cannabis if you plan on being tested within the next month, and to adjust the strength of the substance.