Does Secondhand Smoke Show Up On Drug Test: Will Someone Else's Pot Smoke Get You In Trouble?

Jordan Barnett | Masters in Chemical Engineering
Jordan Barnett | Masters in Chemical Engineering

Over 15 years of experience dodging drug tests.

Does Secondhand Smoke Show Up On Drug Test?

Usually not – but you can never be too careful! 

THC, also known as tetrahydrocannabinol, is the primary active compound in marijuana. Simply put, if you test positive for THC, this is an indicator that you may be using marijuana. However, since secondhand marijuana smoke has so little THC, brief exposure to it usually won’t result in a positive drug test.

This is the general rule, so how much secondhand marijuana smoke does it take for people to fail a drug test? How long does it take before all that second-hand smoke leaves your system? Read on to learn more!

a person smoking a joint

Can I Fail A Drug Test If My Roommates Smoke?

Yes, but there are very specific conditions that will result in a failure. The first is that your roommates need to be smoking in a reasonably enclosed room with little ventilation.

Repeated exposure is another factor that affects drug testing. Even if you’re exposed to a lot of secondhand marijuana smoke, you’re most likely to test positive for THC only in the last two or three hours immediately after breathing it in. That means if it was a one-off where you breathed in a bit of smoke, your body would have enough time to get rid of the THC floating around in your system.

This is not a reason to relax! Even if you don’t breathe in enough smoke to have it show up during a urine test, companies can also require you to take a hair test instead. Those are much more sensitive, and more likely to detect traces of THC.

Can I Get High From Inhaling Secondhand Marijuana Smoke?

Yes. Also known as a “contact high”, this happens when people continuously breathe in secondhand marijuana smoke and feel a slight buzz.  When you breathe in enough marijuana smoke to feel a contact high, you are taking in so much THC that you could fail a drug test.

Don’t worry! Contact highs are pretty uncommon, and would have to happen in very enclosed, poorly-ventilated spaces where a lot of people are smoking marijuana.

What Happens If I Fail A Drug Test Because Of Second-Hand Smoke?

It’s a good idea to avoid marijuana and cigarette smoke for your own health and safety. However, there’s another big reason why you should steer clear from exposure to marijuana smoke: your job. If you’ve been exposed to so much secondhand marijuana smoke that you test positive for THC, this could be a reason for your employer to fire you – especially if your workplace has a zero-tolerance policy for drugs.

This rule also applies for pre-employment tests. Many companies require people to submit to a drug test as part of the job application process. If you fail, they can reject your application.

While employers aren’t allowed by state laws to inform authorities if you fail a drug test, it’s still tough to miss out on opportunities because of secondhand exposure – so be careful!

What Are The Drug Tests That Could Detect Second-Hand Smoke?

The most commonly-conducted drug test is the urine test. Urine drug testing will require you to submit a pee sample for analysis. The lab technician will then analyze the levels of THC in your urine, and see how it compares to the lab’s standard allowable cut-off level. If it goes above that level, you will fail your drug test.

Hair drug testing is more expensive, but it’s a more sensitive and thorough way to detect marijuana use. Instead of a urine sample, the drug technician will simply take a few strands of your hair and use the follicle to see if there’s any THC. The standard hair follicle test, with 1.5 inches of hair, can allow a lab to detect up to 3 months back for previous marijuana exposure. The longer your hair, the farther back the results can go.

How Do I Get THC From Second-Hand Smoke Out Of My System?

There are a few tricks to help people pass a drug test if they’ve recently had secondhand marijuana exposure. Because THC is stored in your body fat, speeding up your body’s metabolism could help it dispose of THC much faster. Dieting, drinking plenty of water, and eating food rich in antioxidants will definitely go a long way in flushing out THC!

However, changing your diet and improving hydration can only take you so far. They’re great long-term solutions, but people who have had more recent and heavy exposure need a faster option if their drug test is near. Fortunately, there are three products which can help anyone pass a drug test, regardless of THC exposure levels.

The Big Three

If you’ve recently been exposed to secondhand marijuana smoke for a long period of time, it could affect your drug test results. If you’ve been given very short notice about an upcoming drug test, there are three products you can use to help you get through it.


For urine drug testing, you can use Clear Choice Sub Solution. It’s the best synthetic urine on the market, with a pH and chemical composition similar to human pee. Because it has urea and uric acid – substances both found in real human urine – it can help you fool a drug test into thinking that you’re submitting a human sample.

Take a look at how Clear Choice performs against competing synthetic urine products by reading our complete overview: Best Synthetic Urine.


Even if your urine test is supervised, or you’re just nervous about swapping out samples, you still have another option: Toxin Rid 10 Day Detox. This detox program consists of taking dietary fiber, a detox drink, and Pre-Rid pills for electrolyte replacement over the course of 10 days, so you can flush out that lingering THC fast.

Find out more about this and how it compares to similar products, by looking at our guide: Best Detox Pills For Drug Test.

Hair Follicle Drug Test

Lastly, if you’re being asked to take a hair follicle test, use Old Style Aloe Toxin Rid Shampoo. Some people have resorted to repeated dyeing and hair bleaching to remove any lingering THC, but this can damage your hair – sometimes, permanently. Old Style Aloe Toxin Rid Shampoo will gently penetrate and soften your protective hair cuticle, gradually stripping it of product and chemical build-up so THC leaves your hair faster.

To learn more about how this product can clean your hair up in just 10 days, check out our article: Best Hair Follicle Detox Shampoo.


No matter how recently you’ve been exposed to secondhand marijuana smoke, or how heavy the exposure was, you have three solid products that can help you pass with flying colors. Clear Choice, Toxin Rid 10, and Old Style Aloe Toxin Rid can all help you fool any drug screening, so you can go to the lab with absolute peace of mind!