How Long Does THC Stay In Your System?
Do The Words “Drug Test” Give You a Panic Attack?
Many different methods exist for testing for drugs, but most employers, insurance companies, government agencies, etc., will ask for a urine test, as this is the industry standard for workplace drug testing and the only method approved for federally mandated drug tests.
What Are They Looking For During A Drug Test?
Delta-9 tetrahydrocannabinol (THC), a cannabinoid found in cannabis, is psychoactive and credited for creating euphoric and psychoactive effects. Your urine is used to test for the amount of just one of the metabolites of THC. A metabolite is basically a chemical produced by the body from another chemical taken in by the body. The metabolite they are looking for is THC COOH.
“It is difficult to say the length of time that you will test positive for cannabis use since the metabolic process of your body converting THC into THC COOH can vary from person to person.”
While THC COOH has no psychoactive effects, it can be detected in your urine for weeks, even months. It is not a marker for current impairment, so it is arguably useless, but nevertheless, THC COOH has become the standard of evidence for determining if you test positive for marijuana use.
How Long After Smoking Marijuana Will I Test Positive?
It is difficult to say the length of time that you will test positive for cannabis use since the metabolic process of your body converting active THC into inactive THC COOH can vary from person to person. Factors such as the quantity of marijuana consumed, frequency of use, method of consumption, and even what you eat and drink can modify the amount of time that traces of THC COOH will be detectable in your urine come test day.
It Was Just One Night… Does That Make a Difference?
It depends. There are several studies that suggest a smaller “window of detection” (the number of days following the last use that a urine sample will produce positive results) and others that suggest a larger window, especially for chronic users.
Most will agree, a one-time user is typically vulnerable to testing positive for up to three days after use. After that, the chances of testing positive greatly decrease because any trace of THC COOH will likely fall below the required threshold for a positive result. The standard for most employment and government testing programs is 50 nanograms per milliliters (ng/ml). It is possible, however, to test positive 7+ days.
Frequent, regular cannabis consumers should not be surprised to test positive for a minimum of one week to 10 days after their last use and up to 100+ days thereafter.
What Can I Do To Ensure I Pass The Drug Test?
As you may expect, there are numerous products on the market that claim to cleanse your system or mask your use. There are even some companies that offer “clean” urine. There are many reasons to be doubtful of these products and their claims. Most do not work, are expensive, and can even be identified in a drug test. Collection facilities and labs have become more sophisticated in detecting a specimen that has been influenced or altered. Cheaters typically get caught.
But don’t panic. There are some simple, inexpensive and legal things that you can do to help lower the amount of metabolites in your urine and influence your test –
- Using a safe detoxification product that naturally accelerates your bodies normal detoxification systems can allow you to cleanse your blood and urine of toxins like marijuana in roughly 3-6 days depending on how many toxins are stored up in your body.
- Never use the first urine of your day. This is typically referred to as “the first void.” Even if you have to stay awake all night or get up early the day of the test, each time you urinate will make a difference. Also, try to avoid collecting the beginning of your urine stream, as this will have the greatest amount of metabolites in it.
- “Flushing” your system – this should only be done with caution. This involves putting large amounts of liquids (not including alcoholic beverages) into your body so that the metabolites will be washed away faster. Although this may be an effective method, it can also be dangerous. Ingesting too much water can cause water poisoning or water intoxication and can make you very ill or even cause death. Cranberry juice is a natural diuretic and will help flush your system faster than water alone. Coffee and tea also act as diuretics. But remember, if your urine is overly diluted, it may raise a flag. To enhance the coloring of the urine so that it appears more yellow, you can add a B vitamin to your diet a day or two before the test.
There is a lot wrong with urine drug testing — accuracy, privacy violations, proof that it improves workplace efficiency or safety. Unfortunately, until alternative methods are more widely available and accepted, it remains the go-to method in the work place.
So how long will marijuana show up in your urine after you smoke it? It depends. Medical Jane explains how long THC stays in your system and more.
How long does Marijuana stay in your system?
Medically reviewed by Carmen Fookes, BPharm. Last updated on Apr 17, 2019.
It varies according to usage
It is impossible for anyone to accurately state the length of time it would take for somebody to test clean for marijuana in a drug test. This is because there are many different variables that impact on the rate that marijuana is both metabolized and excreted (see below).
An estimate of marijuana detection time after last usage is as follows:
|Usage||Estimate of detection time|
|One time only||4-8 days|
|2-4 times per month||11-18 days|
|2-4 times per week||23-35 days|
|5-6 times per week||33-48 days|
|Daily usage||49-70 days after last use*|
*Occasionally, some chronic users with a high tolerance may eliminate THC as fast as a one-time user.
We can give an estimate of the amount of time marijuana remains in the body, but the most reliable way is to test yourself twice weekly until your first, morning urine sample tests clean. However, even this is not 100% foolproof because home drug detection kits have a higher upper limit of detection (usually 50 ng/mL) compared to some other medical testing kits. This means you may test negative, but a laboratory test may still show marijuana in your system.
Note that charts, graphs, or computer programs that claim to be able to predict how long it will take you to test drug-free, are essentially useless at doing this, even though they may say otherwise.
What is delta-9 THC?
Marijuana is produced by the cannabis sativa plant. Cannabis sativa contains over 421 chemicals including 61 different cannabinoids, of which delta 9-tetrahydrocannabinol (delta-9 THC) is considered the most psychoactive. Delta-9 THC has a thick, sticky consistency (somewhere between a solid and a liquid) and is easily vaporized. It readily dissolves into lipids and fats, and once in the body gets deposited in fatty (adipose) tissue, and in the liver, lungs, and spleen.
Delta-9 THC undergoes metabolism in the liver to another psychoactive compound, 11-OH-THC, and then further metabolism to the inactive THCCOOH. CYP2C9 and CYP3A4 are major enzymes involved in this metabolism and both enzymes show genetic variation – this means that some people will metabolize THC faster than normal, whereas others will metabolize it slower than normal.
What variables impact on the time Marijuana stays in your system for?
Individual variables that play a role in how long marijuana stays in your system for and detection times include:
- Body fat: People with more body fat will retain THC for longer. Skinny users have fewer places to store THC.
- Fluid intake at the time of the test.
- Genetics: Fast metabolizers will excrete THC rapidly.
- How frequently you exercise.
- Method and frequency of usage: Infrequent users clear THC faster than chronic users.
- Type of detection test used (blood, hair, saliva, or urine).
- Your general health: Many medical conditions impact on how your body retains, stores, and metabolizes marijuana.
- Other drugs taken: Many drugs interact with CYP2C9 and CYP3A4 enzymes.
- The potency of the marijuana and your tolerance to it can also have an impact.
What are the different ways Marijuana can be tested for?
Firstly, it is important to understand the difference between qualitative and quantitative testing.
Qualitative testing tells you if a substance is there or not.
It does not tell you how much of the substance is there. There will be a cut off point for detection. For example, the Alere DDs 2 Mobile test system used roadside by law enforcement agencies has a cut off level for Delta-9-THC in saliva of 25 ng/ml. Research has shown that this testing system is 97.5% accurate at this cut off (this means that more than 97 people will accurately test positive out of 100 people who have used marijuana in the past 24 hours).
Quantitative testing measures the actual quantity of a substance.
This type of testing is more expensive and time-consuming than qualitative tests and is normally reserved for people who have tested positive in a qualitative test. It needs to be done in a laboratory and is used when a more defined value is needed, say, for prosecution. Quantitative testing can detect minute quantities of a substance, far below the cut off point in a qualitative test. A series of quantitative tests can determine if drug usage is ongoing or has stopped.
The most common ways marijuana can be tested for is in urine, saliva, blood, or hair. Most testing practices look for the presence of THCCOOH which has a much longer half-life (the time it takes for 50% of the substance to be excreted) than delta-9 THC. The half-life of THCCOOH is 20-57 hours in occasional users compared to 3-13 days in regular users.
Estimated periods of detection of the marijuana metabolite THCCOOH
|Test Type||Detection period (estimated)|
|Blood test||36 hours
Some reports suggest up to 7 days with chronic use (>3 months)
|Hair test||Cannot detect first-time drug use in the previous 7-14 days
Every 1cm of hair length represents a one-month window of detection
Detection period depends on hair length but generally 90 days
|Saliva test||Up to 34 hours|
|Urine test||1-4 days
Some reports suggest up to 70 days with chronic use (>3 months)
A false-negative is when the test result is negative for a substance, but the person has been using the substance. A false-positive is when the test result is positive for a substance, but the person hasn’t been using the substance.
Can second-hand marijuana smoke make you fail a drug test?
For kits that detect at the 50 ng/ml level the circumstances would have to be extreme, for example, if you were in a closed car full of marijuana smokers for a couple of hours and you were drug tested the next day. If you are a non-smoker in a ventilated area where other people are smoking marijuana you are generally safe.
Official answer: It varies according to usage It is impossible for anyone to accurately state the length of time it would take for…