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How long does Marijuana (THC) Stay in your system?

This Guide was created by the writers at NeonJoint to teach you the detection times for marijuana (THC) , as well as how long they stay in your system.

A Note on Detection Times

In addition to being able to detect the drugs themselves, drug screenings are designed to detect metabolites -- the byproducts of a substanceleft behind after it has been metabolized by your kidneys and liver. Think of these drug components as the bodily residue left behind. To determine whether you will pass a drug test , it is important to know how much of the illicit metabolites are in your urine, as well as the "Levels of Detection" (LOD), or “cutoff times.” Table 1.2 below will give you an approximation on various detection times; however, it varies depending upon a number of factors such as testing method used, LOD, body type, and the relative overall health of the test taker.

1.1 Half-life of THC

The half-life of TetraHydraCannabinol (THC) concentration ranges between 0.8 to 9.8 days. There is too much human 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. Obviously, frequent users with a slow metabolism will have long detection times.

The only way to reasonably estimate your personal detection time is to consider the highest and lowest extremes (3-30 days) and use your best judgment to form an educated guess. The table below can function as a good guide for you.

Table 1.1
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, relative health of the test-taker, fluid intake at time of the drug test, method and frequency of marijuana use, body type, metabolism, exercise frequency and many others. These are general guidelines only.

1.2 Detection Times: Common Drugs

Table 1.2

Approximate Detection Times of Common Drugs in Urine Using EMIT
Amphetamines 2-4 Days
Barbituates Short-Acting (Secobarbital) 1 Day
Long-Acting (Phenobarbital) 2-3 Weeks
Benzodiazepines 3-7 Days
Cannabinoids 3-30 Days
Clenbuterol (Performance Enhancer) 2-4 Days*
Cocaine 2-4 Days
Codeine 2-5 Days
Euphorics (MDMA, Psilocybin) 1-3 Days**
LSD 1-4 Days***
Methadone 3-5 Days
Methaqualone 14 Days
Nicotine Unknown
Opiates 2-4 Days
Peptide Hormones Undetectable
Phencyclidine (PCP) 2-4 Days
Phenobarbital 10-20 Days
Propoxyphene 6 Hours to Two Days
Steroids (Anabolic) Oral: 14 Days
Parenterally: 1 Month
* .5 ng/mL by GC/MS
** By RIA and GC/MS only. Not detectable by EMIT.
*** By HPLC, RIA and GC/MS. Not detectable by EMIT.
8-14 days, as reported commonly, has been disproven and is incorrect
No data available yet. Being fat soluble, nicotine likely has a prolonged detection time
Detectable by EMIT and RIA, but rarely tested. A lab will only test for LSD when specifically requested

Again, detection times vary depending upon the analytical method used, an individual’s drug metabolism, tolerance, health condition, fluid intake and method and frequency of ingestion. These are general guidelines only.

There are extreme variations. For example, if you use marijuana on rare occasions, your urine may be clean of metabolites in less than a week. Additionally, there is a common and strange phenomenon reported with chronic marijuana smokers. While you would expect a chronic user to have longer detection times, this is not necessarily the case. A chronic user with a high tolerance will eliminate drugs quicker than an occasional user. Chronic users have even tested negative after a week-long smoking binge. Lipid tissue also makes a significant difference. Thin users not only have a faster metabolism, but also lack the fat storage for THC metabolites. Additionally, more body fat will cause a lag in excretion patterns and lead to longer detection times.

As you can see, individual detection times for marijuana are extremely diverse and unpredictable.

Many so-called “informative” websites suggest that you download a program that plots a graph of time versus percentage of THC in your system. The program is called CALC_THC.EXE and can be found easily on the Internet. However, due to the inaccurate nature of the program, NeonJoint does not offer a direct link to download the program. CALC_THC cannot possibly be accurate when considering there is no allowance for potency of the marijuana, nor an individual’s metabolism in the equation.

1.3 A Positive Drug Test Defined

For nearly all drug tests (including instant tests and urine drug testing) conducted in the United States and all NIDA-certified labs, 50 nanograms of THC metabolites per milliliter (ng/mL) defines a "presumptive positive." Years ago this value was originally 20 ng/mL, but too many false positives resulted. The level was the raised to 100 ng/mL to reduce false positives. As of January 1995, the threshold was lowered back down to 50 ng/mL because drinking excessive water could easily bring a positive below 100 ng. While rare, it is possible that employers may use a lower cutoff.  The following table lists cutoffs for many common drugs.



Drug Test Sensitivity Cut-off Levels (As Established by NIDA, WHO and SAMHSA)
Target Drug/Metabolite Concentration (In ng/mL)
Marijuana/Cannabis 50
Cocaine/Benzoylecgonine 300
Phencyclidine 25
Opiates/Morphine 2000
Ecstasy 500
Oxycodone 100
Amphetamine 1000
Methadone 300
Barbiturates 300
Benzodiazepines 300

1.4 Passive or Second-Hand Smoke

Second-hand or "passive marijuana smoke" in a car or similar confined quarters for extended periods of time can cause you to fail the next day. In these extreme circumstances it is possible that second-hand marijuana smoke will raise someone to the 50 ng/mL level. A recent case study conducted by the Army placed volunteers in a room pumped full of smoke for an hour, five times daily. Subjects routinely began testing positive after the second day. Typically, non-smokers are safe in a ventilated area as long as they are not subjected to a hair drug test.

1.5 Decreasing Your Drug Detection Times

Unfortunately, increasing your metabolism is the most effective way to decrease the time period that drugs are detected in your system. Physical activity can increase your metabolic rate as much as two thousand percent, and absolutely nothing beats proper physical training. A high-calorie diet is the next best way to increase metabolism. Consuming mass quantities of high-calorie food will increase your metabolic rate up to 10%. Be advised, however, that a mal-nutritious diet could lower your metabolism up to 10%. Consuming amphetamines could also increase your metabolism. Unfortunately, labs usually test for “speed,” and consumption could easily get you into significant legal trouble. Your best bet is to exercise regularly and moderate your diet.

If after learning about the guidelines for Detection Times you are still troubled regarding your impending drug test, NeonJoint can only recommend that you contact the drug test experts at