This article discusses different types of substances that can create a contact high and whether or not this experience actually constitutes a real “high.” It also covers what the experience is like and how this term is applied when it comes to a marijuana high.

Types of Contact Highs

There are a number of different types of substances and situations that may result in a contact high. These experiences may be different depending on the situation and the substance that is being used.

Psychoactive substances: An experienced acid (LSD) user who is spending recreational time with someone who is “tripping” on LSD may start to feel as if they, too, are under the influence of LSD. Marijuana: The term is also used to refer to the experience of getting intoxicated due to the effects of secondhand marijuana smoke. Placebos: A contact high can also happen when someone has taken a placebo, or a substance containing no psychoactive ingredients. In this case, they may believe that they have taken a real drug when they are around others who really have taken the drug.

The reaction that a person has may be related to set and setting. Set and setting refer to how the individual’s mindset (the set) and their physical and social environment (the setting) impact their hallucinogenic experience. The set and setting have a profound impact on an individual’s experience of drugs, and even the intensity of the drug effect.

Is a Contact High Real?

Unlike the related phenomenon of expectancy effect, in which people experience drug effects when expecting them — either through taking a placebo or “dummy” drug or through taking a real drug — contact highs are not well researched in the drug abuse field. In contrast, the phenomenon of the contact high is well known among people who regularly use substances. Many people who use drugs avoid or seek out other people who use substances specifically to avoid or to induce a contact high. Within the rave culture, a subset of people choose not to use drugs. However, they enjoy the feelings of stimulation and excitement they feel around others who are on stimulating drugs such as ​ecstasy and meth. A contact high doesn’t even require direct contact with the person who has taken drugs. In his review of the book, Tripping: An Anthology of True-Life Psychedelic Adventures, Spalding Gray wrote: “I couldn’t stop dipping in and out of this juicy book, flying from New York to Detroit. At times, it felt like just reading it was keeping the plane up. Wow! What a contact high.”

What The Experience Is Like

As intoxication effects are subjective, meaning they are inner experiences that vary from person to person, it is hard to know whether people who describe having a contact high are really having any perceptual changes. They might simply picking up on and mirroring the mood of the person who is intoxicated. While this is certainly a significant part of what is described by a contact high, some people who have used the substance before may be triggered to experience a flashback, and may actually have some perceptual changes. Flashbacks are a type of distorted perceptual or sensory experience. These are more than just memories; they feel all too real in the current moment. A person who has used a hallucinogen in the past, such as LSD or phencyclidine (PCP), may flashback to that experience as part of a contact high.  While flashbacks have been reported, they appear to be quite rare. In a study published in the journal PLOS ONE, researchers found no association between the use of psychedelics and mental health problems and no incidences of hallucinations or flashbacks.

Marijuana Contact High

Another type of contact high is a marijuana contact high, also known as a secondhand high. In this case, it refers to the possibility of getting intoxicated when around other people who are smoking marijuana by inhaling secondhand cannabis smoke.  In some cases, people actually do this intentionally, a practice known as hotboxing. Others worry, however, that inadvertent exposure, such as indoor or outdoor concerts, might lead to contact high and the possibility of testing positive for cannabis on a blood or urine drug test. Can you really fail a drug test from a secondhand marijuana contact high? In one study, researchers found that people who spent an hour in an unventilated room experienced side effects including tiredness, decreased alertness, and a more pleasant mood. When tested for THC, their urine tests returned a positive result. In a second trial, however, participants were placed in a well-ventilated room with cannabis smokers. This time, they reported few side effects and did not test positive for THC. So while you might be able to get a contact high if you spend an extended period of time in an enclosed, poorly ventilated space with cannabis smokers, you won’t get high or test positive for TCH just by catching a whiff of marijuana smoke, particularly if you are outdoors or in a well-ventilated area.

A Word From Verywell

More research is needed to establish exactly what a contact high is, but the benefit is that generally they are described positively, without the associated costs and risks of really being intoxicated. If you are experiencing unwanted hallucinations, you should consult your healthcare provider. For more mental health resources, see our National Helpline Database.