What Is a Contact High?

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What Is a Contact High?

A contact high is an experience of sensing or perceiving drug effects when in the company of someone who has actually taken drugs, without having taken the drug yourself. A person experiencing a contact high may start to have bizarre thoughts, experience mild pseudo-hallucinations, and find everyday situations hilariously funny. They may also share feelings of fear, anxiety, or panic that are being expressed by the other person.

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.


A contact high may occur as a result of a flashback related to prior use of a psychoactive substance or when taking an inert, placebo substance. A marijuana contact high refers to getting high when inhaling secondhand marijuana smoke.

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.

The difference between an expectancy effect and a contact high is that with a contact high, the person experiencing it need not think that they have actually taken the drug to experience its effects.

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."


A contact high might be related to the psychological experience of being around people who are intoxicated, but research on this effect is limited.

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.


A contact high may lead to pleasant feelings associated with past drug use. In some cases, it is possible to experience what is known as flashbacks to past hallucinogen use, an experience marked by perceptual and sensory experiences that seem real. This experience appears to be quite rare, however.

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.


Unlike other types of contact highs, which are generally purely psychological, a marijuana contact high can be caused by inhaling secondhand marijuana smoke. While it is possible to get high on secondhand marijuana smoke, it requires being in a small, unventilated area for an extended period of time.

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.

If you or a loved one are struggling with substance use or addiction, contact the Substance Abuse and Mental Health Services Administration (SAMHSA) National Helpline at 1-800-662-4357 for information on support and treatment facilities in your area.

For more mental health resources, see our National Helpline Database.

Frequently Asked Questions

  • Can you fail a drug test from a contact high?

    You cannot fail a drug test from a purely behavioral contact high or one caused by the placebo effect. For a marijuana contact high, however, there is a possibility that exposure to secondhand marijuana smoke may lead to a positive result on a drug test. This is most likely to occur if you spend an extended amount of time in a poorly ventilated space with people who are smoking marijuana.

  • What is the placebo effect?

    The placebo effect is a phenomenon in which people experience a real response even though they received a fake treatment. Placebos are sometimes used in research to help determine the effects of treatment. In some cases, a contact high may be an example of the placebo effect. If people think they have taken a substance, they might still experience some effects.

  • What are recreational drugs?

    Recreational drugs are substances that are used for non-medical purposes in order to experience the psychoactive effects of the substance. Drugs are often used recreationally based on the belief that occasional use will not be habit-forming or lead to addiction. Substances that are commonly used recreationally include depressants, stimulants, and psychotropics. According to the National Institute on Drug Abuse (NIDA), some of the most commonly used recreational drugs are marijuana, synthetic cannabinoids, prescriptions medications, and over-the-counter medications.

12 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Goldberg T. Demystifying Drugs: A Psychosocial Perspective.

  2. National Institute on Drug Abuse. What are the effects of secondhand exposure to marijuana smoke?

  3. Benedetti F, Piedimonte A, Frisaldi E. How do placebos work? Eur J Psychotraumatol. 2018 Oct 25;9(Suppl 3):1533370. doi:10.1080/20008198.2018.1533370

  4. Swanson LR. Unifying theories of psychedelic drug effects. Front Pharmacol. 2018;9:172. doi:10.3389/fphar.2018.00172

  5. APA Dictionary of Psychology. Expectancy Effect. American Psychological Association. 2018.

  6. Hayes, Charles, ed. Tripping: An anthology of true-life psychedelic adventures. Penguin, 2000.

  7. Quinn PD, Fromme K. Predictors and outcomes of variability in subjective alcohol intoxication among college students: An event‐level analysis across 4 years. Alcoholism: Clinical and Experimental Research. 2011 Mar;35(3):484-95. doi:10.1111/j.1530-0277.2010.01365.x

  8. Leo H, Melanie S, Martin R, Anil B, Martin G. Hallucinogen persisting perception disorder (HPPD) and flashback-are they identical. J Alcoholism Drug Depend. 2013 Jun 24;1(121):2. doi:10.4172/jaldd.1000121 

  9. Krebs TS, Johansen PØ. Psychedelics and mental health: a population study. Lu L, ed. PLoS ONE. 2013;8(8):e63972. doi:10.1371/journal.pone.0063972

  10. Herrmann ES, Cone EJ, Mitchell JM, et al. Non-smoker exposure to secondhand cannabis smoke II: Effect of room ventilation on the physiological, subjective, and behavioral/cognitive effectsDrug Alcohol Depend. 2015;151:194-202. doi:10.1016/j.drugalcdep.2015.03.019

  11. Starobin B, Jablonski S, Andrle AM, Powers JB. Recreational drugs: effects on the heart and cardiovascular system. In: Encyclopedia of Cardiovascular Research and Medicine. Elsevier; 2018:240-248. doi:10.1016/B978-0-12-809657-4.99731-X

  12. National Institute on Drug Abuse. Most commonly used addictive drugs.

By Elizabeth Hartney, BSc, MSc, MA, PhD
Elizabeth Hartney, BSc, MSc, MA, PhD is a psychologist, professor, and Director of the Centre for Health Leadership and Research at Royal Roads University, Canada.