The effects of using marijuana, whether smoked or eaten, leave a trace of the active ingredient Tetrahydrocannabinol (or delta-9-THC or simply THC) in your system  that can be identified by testing your blood, urine & hair follicles. Traces of THC can be detected in the body for weeks, depending on how much marijuana has been used. 

THC can be detected in the bloodstream shortly after smoking marijuana or even ingesting marijuana. However, the THC is only detectable in the blood for a few hours because it is quickly metabolized into molecules known as metabolites. These metabolites are stored in body fat and are eliminated from the body through feces and urine over time.

How much time? In general, urine tests for marijuana can detect the presence of the drug in the body for about 13 days. However, long-term, heavy smokers have reported positive tests up to 90 days after quitting. 

Because marijuana stays in the bloodstream such a short time blood tests for marijuana are rarely conducted, unless the police suspect the use of marijuana was involved in causing an automobile accident. However, unlike blood alcohol tests, they do not indicate a level of intoxication. 

Approximately 90 percent of the estimated 55 million drug tests performed annually in the United States are urine tests.

Saliva testing is less common and only detects the presence of cannabis for a period of one to two hours following drug ingestion, if at all.

Hair strand testing is considered to be the least effective method of detecting the presence of marijuana use but it is mostly used to detect long term use.

A recent study has found that THC can be detected from a breath test. It won't show the amount of THC, but it could be used a reason to force an individual to undergo a blood or urine test. This would require changes to the law. It is unlikely to happen anytime in the near future, but bears watching.

Employment Drug Testing

Urine tests for marijuana metabolites only show recent marijuana use, not the level of intoxication or amount of marijuana use. Since most employers who drug test have a zero tolerance policy for drug use, any recent use of marijuana that shows up in the results could prevent employment or be grounds for dismissal, whether you took one toke or fifty.

Keep in mind that false positives are rare for marijuana tests. Laboratories screen the urine sample with a immunoassay test, known as the EMIT or RIA. If positive results are achieved, the sample is then screened with a gas chromatograph mass spectrometer (GCMS), which is much more accurate. Plus, there are no known substances that might cause a marijuana urine test to return a false positive. In the past, some over-the-counter drugs such as Advil would cause false marijuana positives, but today's tests are far more sophisticated and that is no longer a problem.

Passing a Drug Test

Beating a marijuana drug test depends on so many different factors that there is no single definitive answer. There is a lot of anecdotal evidence and plenty of urban legends, but little empirical research. If you take a urine test on short notice for employment or any other reason, and you have recently smoked marijuana, you will probably fail the test, especially if you are a regular or heavy pot smoker. The only way to guarantee that you will pass a marijuana drug test is to quit smoking marijuana for a substantial period of time.
5 panel test

Home Drug Testing

If you want to get a read on whether your urine is going to pass a laboratory test, you can purchase a home testing kit. 

These kits allow you to detect the presence of marijuana use, as well other ellegal substances, such as cocaine, opiates, methamphetamine, amphetamines, PCP, benzodiazepine, barbiturates, methadone, tricyclic antidepressants, ecstasy, and oxycodone.

The testing should be done in two steps. First, you take the quick at-home test. It is shows positive, you will most likely show positive when you go for an employment urine test. If it shows negative, and you have the time, you should still send the send the sample to a laboratory for additional testing. Laboratory tests are the most reliable way to confirm that you will be tested negative when you go for your employment test. 

Most Home Drug Testing kits contain a sample collection cup, the drug test and an instruction leaflet or booklet. It may also include a mailer to send the sample to a laboratory.

We don't guarantee that any of these methods will help you pass a drug test. 

The only way to make sure you pass a marijuana or other drug test is to quit using for a substantial period of time.  

If quitting is not an option, or you don't have enough time for the THC to work its way out of your system naturally, you can attempt to beat a marijuana drug test by doing one or more of the following:

1.Dilute Your Urine

Drinking large quantities of water prior to taking a urine test is one of the most effective methods of beating a marijuana urine test, according to recent testimony before Congress by the US Department of Health and Human Services. Drink a lot of water and urinate several times before the test, then drink a large amount of water right before the test. Fill the cup with urine midstream - in other words, start to urinate, then stop, then fill the cup, then relieve yourself fully into the toilette. Some people suggest taking vitamin B-2 to add color back to the urine. This process may lower the percentage of THC found in the urine by diluting it, but it will not totally eliminate THC metabolites. Again, it depends on how long and heavy you have been smoking.

Caffeine, cranberry juice, and most "quick flush" herbal teas marketed as "detoxifiers" may also effective in helping marijuana smokers beat the test. Consuming these and other diuretic fluids just prior to taking a urine test may temporarily dilute the concentration of drug below the threshold of detection. Substances such as Lasix (ferosemide), which can potentially be hazardous to your health, has been popular for over 20 years by those forced into drug tests on short notice.

Creatinine is a normal byproduct of metabolism that is present in urine at specific levels. Creatinine levels are one of several items considered by urinalysis examiners to identify diluted samples. In response, drug-testers may consume high quantities of Vitamin B, riboflavin, and even Creatine supplements to maintain levels within an acceptable range, even though their urine is highly diluted.

2.Use an Adulterant

An adulterant is any substance that is added to a urine specimen to yield a negative result. They may be ingested or added directly to the urine sample. However, common adulterants like bleach, Visine, or glutaraldehyde, as well as many chemical oxidants such as nitrates are screened by the drug testing industry and are readily identifiable.

Several commercial products are used as urine test adulterants, but none are 100% effective. And all of them can be detected by the laboratory. Many brand-name adulterants consist of potassium nitrate, which many labs treat as a positive test for illegal drugs.

There are various substances that are supposedly capable of flushing the body of traces of marijuana. Some of them may be effective if used over an extended period of time, but none of them are proven to work in the short term. Over an extended period of time, the marijuana will leave your system naturally. However, that being said, there are people who swear by these products, both natural and artificial, so if you need to, take your chances and hope for the best.


Zinc sulfate is believed to bond with THC metabolites, rendering the molecules too large to filter through the kidneys. These metabolites are then redirected to the feces, where the majority of THC metabolites are eliminated anyway. This has yielded only mixed results at best.


Papaine, an enzyme found in the papaya fruit, was reported in The Journal of Forensic Toxicology to reduce the presence of marijuana metabolites and is currently undetected by standard laboratory procedures.


While scientific studies have demonstrated that iodine may be effective at eliminating some marijuana metabolites.
Marijuana Testing
Copyright: 2013 Imaginary Enterprises

​​We do not condone or encourage the illegal use of marijuana.  

The information provided here is only intended for those who can legally buy and consume marijuana. 


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