Can You Get Second-Hand high?

Can You Get Second-Hand high?

Published on Jul 24, 2019

Can You Get a Secondhand High?

So you're driving through Denver, sitting in the backseat of a buddy's car. Your friend in the front pulls out a joint and proceeds to light it. Normally you would join in without a second thought. However, you just got a new job and they drug test. Should you be worried?

Gras Grun

Well, that depends.

Getting high from secondhand smoke, better known as a "contact high," is a story we've all heard growing up. But is it true? Can you get a contact high from weed? A few researchers at John Hopkins University wondered the same thing, and they decided to answer the myth once and for all.

The 2015 study tested the effects of six people sitting in a small room smoking weed, with several additional individuals present having never taken a puff themselves. In the first round of the experiment, researchers ventilated the tiny room. The individuals who didn't "pass it to the left-hand side" came out of the room smelling like they just left a Grateful Dead concert but were otherwise clear-eyed and unfazed. In the second round of the study, the researchers elected to hotbox the small space. What is hotboxing? Basically, the vent to the tiny room in the study was closed off, eliminating all airflow causing the smoke to get highly condensed. As a result, the participants who were not smoking actually did get high.

What does this mean?

Ultimately, marijuana contact highs are a real thing but only under extreme conditions. You need to be in a small, enclosed space, with large amounts of potent marijuana smoke to get any tangible effects. Although hotboxing a car is a common situation, don't worry about inhaling too deeply, just simply crack a window. 

What Do Contact Highs Feel Like?

During the experiment, participants who sat in the enclosed room without smoking reported feeling "relaxed" and "tired" after coming out of the study. Effects of the contact high were similar to those reported by the participants actually smoking, just at a much lower rate.

Can You Get High From Smelling Weed?


Getting a contact high requires an immense amount of smoke in an unventilated space for extended periods of time. So walking past that Volkswagen Bus and getting hit with a face-full of that sticky icky won't affect you in the slightest.  Even in a more personal setting, like a concert venue, smelling weed from the long haired guys next you won't cause any actual effects - unless of course, you ask them to pass it!


Can You Fail a Drug Test from a Contact High?

Again, it depends.

The good people of John Hopkins decided to test this out for us and came up with some definitive answers. Of the participants who sat in the small room with ventilation, none had detectible amounts of THC in their urine. However, of the individuals who let themselves saturate in the hotbox conditions, about 60% came out on the other side with detectible amounts of THC in their bodies, enough to fail a drug test.

Bottom line - if you know you're going to be tested soon, it's best to avoid any tiny, unventilated spaces with your stoner buddies. Other than that, don't be afraid to attend any parties. As long as you're not smoking yourself you have nothing to worry about.

How Much Can I Smoke Without Failing a Drug Test?

In another instance, you decide to join in the rotation and hit that joint. Will smoking one joint show up on a drug test?  The answer depends on a number of factors, from body size to metabolism speed and overall level of health to previous consumption habits.

Martin Alonso

Generally speaking, if you haven't smoked in a long time then the answer is that THC will stay in your body for only a short period. An analysis conducted on THC retention time in the body found that sporadic smokers tested positive for THC on an average of 1-3 days after smoking. If you are otherwise THC-free and smoke one time, then your body likely won't retain the THC for more than 24 hours.

Obviously, the amount of weed you can smoke without failing a drug test depends largely on when the test is (amongst other factors). If you're novice smoker who has to pee into a cup tomorrow morning, you should probably take a hard pass on that blunt. But if you drank a few too many wine coolers last night and couldn't resist taking a hit or two, you'll likely be THC free within a couple days.

How Long Will Weed Stay in my System?

Now, let's say you just spent a week in Amsterdam eating moon pies every day. How long until you can you pass a drug test after smoking weed several times? The simple, general rule of thumb is as follows: the more weed you smoke, the longer it stays in your system. An analysis found that regular smoking (several times per week) can result in positive THC results for 7-21 days. However, if you have been hanging out with Willie Nelson for the last month, chronic marijuana use (smoking daily) can cause weed to stay in your system for a lot longer than 30 days.

Ask five different people about tips to flush marijuana out of your system and you'll get five different answers. The key is determining the amount of THC and its metabolites in your body, the type of drug test that will be administered (blood test, urinalysis or hair test) and the specific testing levels for each drug screening.

In general, it's good to remember that 50% of THC metabolites in your body will decrease every 7 days. This means that most consumers will no longer have THC metabolites after three to four weeks.

There are many myths floating around relating to hydration, drinking cranberry juice and exercise but not all of these will work (and some often have a negative result).

For example, many say Hydration has a large effect upon THC retention in your body, with more water equating to less retention time. Although more studies are necessary, it wouldn't hurt to channel your inner Waterboy and start hitting the H20 a few weeks before a test. However, if your test is the next morning, don't go crazy. Drinking too much water too fast can be bad for your kidneys and being overhydrated can invalidate the test, forcing you to come back and repeat the process.

As we mentioned, overall health and body fat levels will also affect how long weed stays in your system. THC molecules are lipid-soluble, meaning that they build up in body fat. Counter to common thought, if you start working out heavily right before a drug test, you might actually risk releasing THC metabolites into your body since exercise breaks down fat cells. Feel free to work out if you have several weeks/months before your test, just be sure to stop a few days beforehand.

Note that If you consume heavily and consistently, you will most likely need to look into secondary methods to help pass a drug test, including detox drinks and synthetic urine, etc.

Got a comment? Let us know what you think and share your stories below!


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