Can You Get A Contact High From Second-hand Cannabis Smoke?

You probably heard the phrase “contact high,” about someone breathing secondhand smoke and feeling a buzz, but can it really make you stoned?

Alyssha Bal
Published in
3 min readMay 19, 2020


You’ve heard it several times that some people fail drug tests when they are not weed smokers. The argument behind this is that they may have inhaled second-hand smoke and therefore got what is commonly referred to as a “contact high.” So, what exactly is a contact high, and does it really happen? This article answers that including whether or not you can fail a drug test for being in a room with someone who is smoking cannabis.

What Is Contact High?

Secondhand high and contact high are used interchangeably, meaning inhaling second-hand smoke. This happens when a sober person comes into close contact with someone who is smoking. Maybe you live with a smoker, or you attended a party where everyone else was smoking except you. That’s what’s called secondhand exposure, and people believe it can make you high.

Is It Possible To Get High After The Smoke Is Exhaled?

The National Institute on Drug Abuse (NIDA) claims that contact high is not a real thing but a psychological phenomenon. You can only get secondhand high if you’re exposed to extremely high conditions. According to the institute, extreme conditions that can make a non-smoker high can only happen when the smokers exhale the smoke right on her face in very copious amounts.

This means it’s almost impossible to get high on exhaled smoke. Very little THC is released back to the air when exhaled. NIDA argues that being in a room with people smoking for up to an hour does not get you high. Only up to 16 joints can start to exhibit some signs of getting you high.

What does the research say about secondhand highs?

There are a lot of studies that have been carried out about secondhand high, what it really means, and whether it happens. A study carried out by Johns Hopkins University concluded that exposure to extreme conditions of marijuana could make non-smokers high. Sitting in an unventilated room with smokers makes you start feeling the effects, and your urine or blood may test positive for THC.

Other researchers documented in the British Journal of Anesthesia 50% of THC plus other cannabinoids get to the smoke, and someone else can inhale them. However, experience smokers can hold up the smoke to the lungs, and all the cannabinoids enter their bloodstream with very little THC released in the air to be inhaled by a different person.

Other studies carried out in the 1980s suggest that cannabis has very little acute toxicity, and feeling the effects without inhaling directly is minimal. Other studies disagree with this conclusion and instead suggest that THC has undergone different cultivation techniques and technologies, and its potency from modern-day marijuana flowers are greater than the ones used in the 60s and 70s. However, several researchers still suggest that smoke from marijuana is less carcinogenic than that from cigarette; hence won’t get you high easily.


As long as you’re not in an unventilated room with heavy smokers, then you should worry less about a high amount of THC entering your system. It’s also unlikely to get high from smelling weed or passing through the remnants of secondhand weed. High contact is, therefore, possible but under extreme conditions. Sometimes you’ll only feel high because of the psychological effects, and you’re not going to fail a drug test for secondary exposure.

Originally published at on May 19, 2020.



Alyssha Bal

Cannabis connoisseur | Philly native | based in Berlin, Germany