Is There Such a Thing as a Contact High?

In my formative days, I remember joking with friends at a party that the weed smoke was so thick we’d get a contact high just from breathing. Fast forward to Portland, where I’m always getting a whiff of weed being smoked somewhere, and I’m wondering: Is there such a thing as a contact high? —Brett

Not to be a buzzkill, Brett, but you seem to have misunderstood the term “contact high.” While it’s true that for the past few years some people (mostly small-town sheriffs and high school guidance counselors) have been using the phrase in reference to weed smoke, the original meaning from Tim Leary onward has always been getting high from being around people on drugs without taking any yourself.

Do contact highs really happen, or are they just an excuse sleazy guys use to try to hang out with girls on molly? Chemist and author Alexander Shulgin (of PiHKAL and TiHKAL fame) famously documented a group trip in which two latecomers “turned on” despite having skipped dosing. Were they keying into some higher consciousness?

Maybe not. A study in 2019 found that 20 out of 33 college students at a simulated party reported mind-altering effects after taking an inert pill they were told was a new psychedelic; the deception was augmented by confederates in the crowd pretending to be tripping. The fact that you can get a contact high off someone who’s faking it strikes me as more placebo effect than mystical connection.

But what you really wanted to know is whether it’s possible to get secondhand stoned. The answer is yes, in theory, though in actual practice the chances are vanishingly remote. We’ll put aside the fact that most ambient cannabis smoke has been filtered through some user’s lungs (and that most folks eat or vape their weed these days) and follow the science.

A 2015 study from Johns Hopkins found that the only way to produce appreciable secondhand stoning was to reduce the ventilation in the experiment room to virtually zero. Even then, a full hour of continuous hotboxing on the part of the study’s six designated ganjateers produced only mild effects, with just one of the six nonsmoking test subjects absorbing enough THC to show up on a standard drug test. (Granted, three of the others were later seen at a record store buying Yes’ Tales From Topographic Oceans on vinyl, but that’s probably just a coincidence.)

Questions? Send them to dr.know@wweek.com.