May 17, 2015

Can you Fail a Drug Test from Secondhand Marijuana Smoke?

May 17, 2015
Can you get secondhand high?

What is a Contact High?

Maybe you’ve heard your dad talk about it when he went to a Three Dog Night concert in 1970, or maybe you’ve experienced it in the backseat of hotboxed Lincoln. If you’ve spent any time as a marijuana smoker, you’re likely familiar with the term contact high: the inhaling of secondhand marijuana smoke, sometimes resulting in minor psychotropic effects.

Perhaps you’ve had a friend who swore up and down that they got high even though they don’t smoke pot, or, heck, maybe you’ve experienced this phenomenon yourself when, say, taking a break from cannabis while your friends pass around the bong. It can be stressful hanging with your weed smoking pals if you’re trying to abstain, especially if worried about a forthcoming drug test, begging the question “is it possible that I failed a drug test but did not smoke weed?”

The short answer: possibly.

Can You Fail a Drug Test from Secondhand Smoke?

A more pressing question is “Can you get second hand high?” to which the answer is: absolutely yes. This published scientific study confirms that “exposure to secondhand cannabis smoke results in absorption of cannabinoids,” but that “[r]oom ventilation ameliorates the effects of secondhand cannabis smoke exposure.”

In this study, two groups of non-marijuana users were enclosed in a room with a specially designed air control system and subjected to secondhand cannabis smoke (11.3% THC – weak sauce if you ask me) for one hour, with one group experiencing no ventilation and the other having regular ventilation. The result:

Exposure to secondhand cannabis smoke under unventilated conditions produced detectable cannabinoid levels in blood and urine. … One urine specimen tested positive at using a 50 ng/ml cut-off and several specimens were positive at 20 ng/ml. Exposure under ventilated conditions resulted in much lower blood cannabinoid levels, and did not produce sedative drug effects, impairments in performance, or positive urine screen results.

In other words, if you’re not smoking cannabis yourself, it’s way less likely to test positive for THC from secondhand marijuana smoke—and way less likely to experience contact high—if your friends are passing around the joint with the windows open or outdoors. 

Would a Contact High Fail a Drug Test If I Didn’t Even Smoke Weed?

But wait, you might be thinking to yourself, I didn’t even smoke! I certainly didn’t get high! So, why would secondhand marijuanasmoke make me test positive for THC? 

For the record, most drug tests have a cutoff level of 50 nanograms per milliliter (ng/ml), with some even being as low as 15-20 ng/ml. As indicated by the study above, it took only one hour of exposure to secondhand smoke of some pretty trash weed to achieve these levels.

Moreover, you’re more at risk if in the presence of joints or blunts where there is smoke constantly being generated. The smoke coming off a joint or blunt hasn’t been “filtered” through anyone else’s lungs, meaning there’s a greater chance for THC absorption into your system via secondhand smoke. Suffice to say, even if you aren’t hitting the blunt along with the rest of your friends, you’re still at risk for testing positive for THC on a drug test.

Avoiding Second Hand Weed Smoke to Pass a Drug Test

Both the effects and risks of a severe second hand high can be almost completely mitigated with proper airflow. If your pals are seriously smoking pot and you don’t want to risk failing a drug test because of contact high, turn on the AC, turn on the fan, open a window, or take it outside. Your risk of failing a drug test depends almost entirely on how intense the concentration of smoke in your hotbox.

Conclusion: Will Secondhand Marijuana Smoke Make Me Fail a Drug Test?

“Under extreme, unventilated conditions, secondhand cannabis smoke exposure can produce detectable levels of THC in blood and urine,” according to the study. In other words, if you’re worried about an upcoming drug test while hanging out with your weed-smoking friends, maybe crack a window.


1. Can you fail a drug test for secondhand Smoke?

Probably not in most cases. In order for you to actually fail a drug test from a contact high or from second hand weed smoke, you would almost certainly have to be in an unventilated room or space at the time the marijuana was smoked.

2. How do I dispute a false positive marijuana drug test?

If you believe your test results have yielded a false positive for marijuana use, you should let your administrator know immediately and request a re-test, because you did not consume marijuana. In instances where your administrator might be reluctant, consider suggesting that you will pay for the second test yourself.

3. Can you fail a hair drug test from second hand weed smoke?

Hair follicle drug tests for pot are used to detect patterns of repeated use and are highly unlikely to trigger a positive after just a single exposure or contact high. If an individual has a history of marijuana consumption or high levels of secondhand exposure, a positive would be a plausible result.

4. Can you fail a drug test for smelling uncombusted flower or concentrate?

It is not possible to become high or intoxicated simply from smelling weed flower or buds that have not been burnt or vaporized. 

Searches Similar to Drug Testing for Weed Contact High on The Weed Blog

At The Weed Blog we strive to produce the latest online news resources regarding marijuana. We also review various strains of cannabis and their edible counterparts. We are committed to helping you find valuable information about marijuana on our website. With marijuana laws constantly changing, learn from us what you can do to promote activism in your area. Otherwise, consider these other top-tier articles regarding cannabis cultivation:

How To Pass A Drug Test For Cannabis 

How To Pass A Hair Follicle Drug Test For Marijuana 

Can Someone Fail A Drug Test For Simply Touching Marijuana? 


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