May Vendor of the Month: Keef - 30% Off Medical and Recreational Products

What is a Cannabis Contact High?

07/17/2020 All About Cannabis

There have been myths and legends surrounding cannabis almost since its discovery. While the rumors surrounding this magical plant have changed over the centuries, the prohibition and intentional suppression of information added fuel to the fire. One such myth is the infamous contact high. It is rumored that one either can or cannot get “high” from inhaling second hand marijuana smoke.

While it is fun to argue either side, the idea of possible effects of secondhand smoke can be life changing for someone who is sober or could be drug tested. If you’re looking to end the debate of the contact high, look no further. Scientists have turned their attention to the contact high phenomenon and conducted legitimate research to find a conclusion. We’ll be adding to your ever growing database of cannabis trivia and busting the contact high myth.

Is second hand pot smoke psychoactive?

secondhand-pot-smokeThe short answer is yes, but some smoke is more psychoactive than others. We’re talking science, and as always, there are variables to consider. The potency of secondhand smoke is dependent on a number of factors such as the method of consumption and the smoking style of the individual who is doing the smoking.

A study published by the British Journal of Anesthesia  in 1999 discusses some of these numbers. When a person smokes a joint, about 50% of the THC and other cannabinoids are inhaled. The amount of THC that is absorbed into the lungs depends on the smoker. The longer someone holds in their hit, the more THC will be absorbed. The article mentioned that if someone holds the smoke in their lungs for some seconds, chances are that all of the cannabinoids will be absorbed, leaving the secondhand smoke virtually non-psychoactive.

If someone immediately exhales after inhaling pot smoke, there will still be a sizable amount of THC in the smoke. The other factor to the smoke itself is the smoke that doesn’t get inhaled. This is where the method of consumption comes into play. When smoking out of a pipe, bong or vaporizer there is little to no residual smoke that is not inhaled by the smoker. When smoking a joint there is a small, but constant stream of smoke emanating from the lit end. Since that smoke hasn’t been inhaled, it is psychoactive with about 50% of the plant’s present cannabinoids.

Will secondhand smoke cause a failed drug test?

Much like the psycho-activity of secondhand smoke, there are various elements to consider such as the amount of smoke in the air, the size of space you’re in, and the space’s ventilation.

A 2015 study published by NCBI took to the “contact high” debate and examined the exposure to secondhand marijuana smoke of non-smokers in ventilated and non ventilated areas. They constructed a chamber for the subjects to smoke in that was designed for ventilation control. After each experiment the non smokers were tested for THC levels in the blood and urine. The non-smokers gave a self assessment of any mental changes as well as a Digit Symbol Substitution Task to determine their performance. The first experiment was conducted in the non-ventilated chamber with six smokers who were all smoking joints. All participants were inside the chamber for one hour.

The results showed that the non-smokers tested positive at 20-50 mg/ml in their urine as well as notable changes in their performance and mental state. In non-scientific terms, they got a contact high and it showed up on a urine test. They found that none of the non-smokers in the ventilated experiment tested positive for THC in their urine. Though there weren’t quantifiable amounts of THC in the systems of the nonsmokers in the ventilated chamber, a few participants reported feeling various effects such as fatigue and the munchies.

So, is the “contact high” fact or myth?

After going through the data from the studies that have been conducted, it’s safe to say that the mythical contact high isn’t mythical after all. However, it is harder to get high from second hand marijuana smoke than some may have thought. In order to get a contact high, one must be in an unventilated space with people who are smoking joints or inefficiently smoking in other ways for an extended amount of time.

These conditions will cause somebody to fail a drug test as well. If someone is smoking in a well ventilated area or outside, the chances of getting high from the secondhand smoke or failing a drug test are small. Since there are so many variables to consider in terms of the effects of secondhand marijuana smoke, it is up to the individual to determine if it is safe and/or worth potential amounts of THC in their system.

Tips for limiting second hand marijuana smoke

  • Don’t “smoke” your weed

The best way to avoid secondhand smoke is to avoid smoking. Since most of the cannabinoids are absorbed by the lungs when inhaled, dab pens, vaporizers, edibles, or tinctures are great ways to reduce the amount of THC in the air.

  • Smoke in a well-ventilated area

The results of the 2015 study found that the non-smokers tested negative for THC in the ventilated chamber, so smoking with the window open or in a backyard is a great option if you’re with someone who doesn’t wish to inhale second-hand THC.

Tips for a proper “hotbox”


  • Close the windows

The experiment found that the unventilated chamber produced higher amounts of THC in the urine of the non-smokers than in the ventilated area.

  • Smoke joints

As mentioned before, joints are the least efficient method of consumption in terms of how many cannabinoids are lost from the tip of the joint. Smoking joints will ensure that there is more residual THC floating in the air.


We know some of you pot-smoking readers are interested in a proper “hot box”, now you have science on your side. We don’t encourage any unsafe behavior and recommend some ventilation for proper air quality and oxygen levels. As always, thank you for reading and please, consume responsibly.



Join our inner circle!

Receive store discounts and product alerts straight to your phone!

Our Latest Articles




Heroes in Weed: Keith Stroup

Culture & Entertainment




Dogs, Marijuana and Accidental Consumption

Health & Wellness




The Most Anticipated TV Shows for 2022

Culture & Entertainment




All About Cannabis Topicals

Health & Wellness




Marijuana Education & Careers: Job in MJ

Culture & Entertainment




Marijuana and Paranoia - No Need to Worry

Health & Wellness

Customer Reviews

Write a review

Jared G.

Friendly people . Amazing flower. Been going here almost 3 years now and NEVER had ANY issues !!! Love y’all !

Phil B.

Some of the best deals in Denver. Friendly budtenders and lots of great products. We will be back again for sure! Our first stop!

Cameron D.

Love these guys. Amazing buds. Amazing prices. Medical patients this is the best place for quantity and affordability without sacrificing quality.

Bailey E.

BEST DISPENSARY EVER. Everyone is nice and treats me well they even corrected something for me that was wrong 2days before hand. Good management and staff 10/10 recommended

Michael D.

So pleasantly surprised finding this jem. Great selection and extremely knowledgeable people to help you find your way. Prices are superb and product is top quality.

Tamika L.

Great shop….great attitudes….loved the selection of strands and different edibles they have. Will be back!