How long to wait after smoking weed to take a drug test?

How To Quit Weed Easily Without Withdrawal Symptoms.

  • The Proven Formula To Quit Weed Easily For The Long Term
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  • The Highest Rated Consumer Rated Detox Kits To Stop Smoking Immediately! 

It doesn’t matter what pro-drug activists say. However much employment-based drug screenings won’t affect productivity, many employers still require one. And one’s continuous employment is still largely dependent on a clean drug screening result.

It’s the same if you’re applying for a job. A drug test is one common requirement across jobs and industries. This is especially true if you plan to work for a government or private institution. Whether it happens before employment or during your tenure, they will test for illegal substances. And here’s what you need to know about it.

The Methods

How will they determine if you have any illegal substances running through your system at the time of the test?

There are four basic ways:

  • urine – typically collected at remote locations using a specially-designed, tamper-resistant cup
  • hairTHC, the active component in marijuana, tends to stay in the hair permanently; most commonly used test for casino employees. Up to 50 hair strands 1 ½ inches from the scalp are used.
  • saliva – highly sensitive and detects drug use during the last few days, difficult to adulterate. Detection time is usually between 12-24 hours.
  • blood – most expensive, most intrusive and most accurate method of testing

Hair testing is one of the most accurate ways to test for the presence of marijuana. But many employers choose to use urine because at $40 to $70 per test, it’s more cost-effective than the $65 to $95 for hair tests.

And these are the devices used:

1. Instant Test

This is the most widely used test because it is convenient. Employers use it. Even court systems do, too. It’s mainly used to identify if a non-negative specimen needs further lab tests to confirm.

Instant tests can be one-drug dipstick tests or the more advanced cup with test strip and adulterant check built-in. Results can come in at a very quick 2 to 4 minutes for the simple dipstick test.

2. Immunoassay

This measures the concentration of a substance in solutions containing complex mixtures of other substances. Serum or urine usually undergoes immunoassay methods. The accuracy has been pegged at 97-99%, with false negatives being more common than false positives.

3. Gas chromatography

This test separates urine extracts into the component parts. Compounds are identified once separated through each chromatographic column.

The most precise way to test for illegal drugs, though, is to combine gas chromatography (GC) with mass spectrometry (MS). Once GC has separated the compounds, MS is used to provide the exact molecular id of the compounds.

Detection Time

Detection Time

Tick-tock, tick-tock…
Image: Alan Cleaver / CC BY

Tetrahydracannabinol, or THC, is the active component of weed. It has a half-life of roughly 7 days. What does that mean? Half-life refers to the amount of time it could take for the drug to be eliminated from the body.  However, while the average for weed may be 7 days, complete elimination of a single dose may actually take up to a month.

The amount and frequency of toking also affects detection times.

frequent, chronic users  + slow metabolism = long detection time

infrequent users + fast metabolism = short detection time

Data Chart

Data from

Of course, other factors affect detection time, too. Among them:

  • drug potency
  • tolerance
  • patient’s condition
  • fluid intake
  • body type
  • exercise frequency

But generally, if you are a rare weed smoker, your urine could be clear of metabolites in as little as less than a week.

And logically, chronic users should have the longest detection times with very slim chances of passing a drug test. However, some chronic users with high tolerance for weed have been known to pass marijuana out of the system as fast as infrequent users do. Very thin people are also mostly incapable of storing THC metabolites and thus pass drug tests more than those who are fatter.

Testing Positive

Test Positive

Image: tango 48 / CC BY

What results to a positive test?

For most labs and instant tests, that’s defined as “50 nanograms of THC metabolites per milliliter.” It used to be that the benchmark was just 20 ng/nL. But that, unfortunately, resulted into a lot of false positives. The threshold was therefore raised to 100 ng/nL. But in January 1995, it was lowered back to the 50 ng/nL that’s still in use today.

If you test non-negative, the sample is sent to undergo a GC/MS test to determine the specific metabolite that tripped the immunoassay result. Here, the level is set at just 15 ng/nL.

And yes, there have been rare instances where even inhaling secondhand marijuana smoke caused a person to test positive. But that’s only in situations where exposure is extreme. So if you’re in for a drug test tomorrow, it’s never a good idea to spend the night cooped up in a car full of pot smokers.

Testing Clean

Smoking Weed

How long are you gonna harbor this tiny blunt inside your body?
Image: Shawn Tron / CC BY-SA

How long will it take before I can take a drug test and come out clean?

That’s really the question you want to know the answer to, isn’t it?

The answer, unfortunately, isn’t as clear-cut as you’d expect. Remember the many factors listed above? Those are the very same reasons why it’s hard to determine the exact time. So what can you do then?

Stop smoking. And then test yourself.

You’d definitely have to weed up if you know a test is imminent. After you’ve stopped, test yourself twice a week until your urine comes out clean. There are many drug testing kits available commercially. Note how much time has elapsed. This would be the normal turnaround time for you to detoxify yourself.

Cheating Your Way to a Clean Slate

Getting desperate? Need to produce a clean drug test result ASAP?

Be careful, labs are mostly able to tell if you have tampered with the samples.

  • clear urine is a red flag that the sample has been watered down
  • Vitamin B complex is usually used to color the urine yellow, but many go overboard and produce a more neon green color
  • Replacing urine with other substances will mean the lab cannot detect drugs, but the sample will be rejected and tagged as adulterated anyway. Why? Because urine has creatinine. If the level is too low, it’s a cause of concern.

Other things like pH level and specific gravity are also noted to ensure that the urine is within the acceptable, normal ranges and has not been adulterated.

It’s never a good idea to tamper with your drug testing samples, though. It’s always preferable to just detoxify.

Cleaning Up, Clearing Up


You might need to toss out the bongs
Image: Rafael-Castillo / CC BY

Detoxifying from weed isn’t so hard, really. You just need to commit your time and effort. There are a lot of products available to help you out.

Be careful with do-it-yourself instructions abounding from the internet however. Many will just suggest a combination of water, sugar and vitamins.

Too much water can actually just flood and overwork your kidneys. And THC can’t be flushed out, anyway. It adheres to fat cells, so exercise is really the best way to burn it off.

Remember, it’s better to go reliable detox sites to guaranty that you’re getting clean the right way. So if you have a drug test coming up, don’t dilly-dally. It’s time to start cleaning up.

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