Drug Test Detection Times
Drug tests detect not only drugs but metabolites as well. Metabolites are the byproducts of a substance after it has run through your system. To determine whether you will pass or not, it is important to know how much of the illicit metabolites are in your urine, as well as the test “cut off,” or Level of Detection (LOD). Usually marijuana tests will have a cutoff of 50ng/mL, but it can be as low as 25ng/mL. Home testing can tell you whether your level at the time of the test is above or below the 50ng/mL level, but it will not tell you the exact level of THC metabolites in your system.
Marijuana Detection Time and Half-Life of TetraHydraCannabinol
The half life of THC concentration is about 10 days. There is way too much variation to even approximate how long THC will be detected in the urine of an individual. Infrequent users with a fast metabolism will have the shortest detection time. Frequent or chronic users with a slow metabolism will have the longest detection times. The only way to estimate a detection time is to consider the lower and upper bounds (3-50 days), and estimate based on the factors outlined here.
Marijuana Detection Time Based on Usage
|Usage at 1 time only||5-8 days|
|Usage at 2-4 times per month||11-18 days|
|Usage at 2-4 times per week||23-35 days|
|Usage at 5-6 times per week||33-48 days|
|Daily Usage||49-63 days|
Note: Detection times vary depending on many factors, including drug potency, tolerance, patient’s condition, fluid intake at time of test, method and frequency of marijuana use, body type, metabolism, exercise frequency and many others. These are general guidelines only.
If you use marijuana on rare occasions, your urine may be clean of metabolites in less than a week. There is a common and strange phenomenon that occurs with chronic users. You would expect a chronic user to have the longest detection time and the smallest chance of passing. This is not always the case. A chronic user with a high tolerance may eliminate drugs as fast as an occasional user. Chronic users have tested negative after a week long binge. Fat tissue also makes a huge difference. Skinny users not only have a faster metabolism (usually), but also lack storage for THC metabolites. The more fat a person has, the more THC metabolites will be stored in the body and thus the longer the detection time is for a user.
How Long Will It Take Until I Test Clean?
This is the single most frequently asked question about drug tests. It is impossible for anyone to estimate the time it would take for someone to test clean. The best thing you can do is test yourself after you have stopped smoking pot. Test about twice weekly until your first urine of the day tests clean. That is how long it takes you to detoxify your system after your normal smoking has. Even that will vary depending on your level of usage prior to abstaining and your level of physical activity while testing yourself.
Please be warned that computer programs, charts (including the one above) and graphs are virtually useless in determining how long it will take you, the individual, to test negative. Do not listen to sources who may tell you otherwise. Again, these are merely guidelines. If you are still interested in learning about various experiments regarding detection times, NORML has posted some valid information on the topic.
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How is a “Positive Test” Defined?
“50 nanograms of THC metabolites per milliliter” defines a presumptive positive by most laboratories and instant tests. This value was originally 20 ng/mL, but too many false positives resulted. So the level was raised to 100 ng/mL to reduce false positives. As of January 1995, the threshold was lowered back down to 50 ng/mL because it became known that drinking excessive water could easily bring the level of metabolites in the urine below 100 ng/mL. Some employers may use a lower cutoff, but that is rare. If a specimen screens non-negative for THC (anything other than negative or fails an integrity test), the specimen is then sent through a Gas Chromatograph/Mass Spectrometer (GC/MS) for the specific metabolite tripping the immunoassay screening. This level is set at 15 ng/m, and is used as the ultimate confirmation for a positive on your drug test.
Can Secondhand Smoke Cause a Positive Drug Test?
In rare occurrences, secondhand marijuana smoke can cause you to fail your drug test. It is possible that secondhand marijuana smoke will raise someone to the 50 ng/mL level. However, extreme secondhand exposure is required. For instance, being in a closed car full of pot smokers for several hours might cause someone to test positive in a drug test the very next day. Non-smokers are safe in a ventilated area such as an average living room or garage where partygoers are smoking pot.
If you are even slightly concerned about receiving a positive drug test, call our Detox Partner at 1-877-247-1354 or email them at firstname.lastname@example.org. After calming hundreds of thousands of test-takers over the years, they are well-equipped to not only calm your fears, but find the right solution for you.
What About Other Drugs? How Long Do They Stay In My System?
According to a survey by Quest Diagnostics, 50% of all drug test positives are for marijuana. What about the other 50%? The table below shows how long drugs other than marijuana typically stay in your system:
|Marijuana- Single Use||1-7 + days||12-24 hours||Doubtful||
|Marijuana – Regular Use||7-100 days||2-7 days||
|Amphetamines||1-3 days||24 hours|
|Cocaine||1-3 days||1-3 days|
|Heroin, Opiates||1-4 days||1-3 days|
|PCP||3-7 days||1-3 days|