A puff of smoke in the air, by hobo_018 via iStock

Photo Credit: hobo_018 via iStock

Can You Get a Contact High?

High There

By High There

March 28, 2022

Not unlike second-hand cigarette smoke, it can be natural to feel concerned about whether those around you may be susceptible to secondhand cannabis smoke; whether you’re a cannabis enjoyer yourself or a non-smoker who may be worried about the effects, there are many reasons why you may want to learn about a contact high.

In today’s article, we’ll break down what contact highs are, the effects they have and research surrounding the topic. Let’s delve in.

What is a Contact High?

A contact high involves the idea that a sober person may experience the effects of a drug just by being near someone using them – in this case, by breathing in the secondhand cannabis smoke that the user exhales.

Ultimately, when you burn cannabis by smoking, the smoke has the potential to cause an involuntarily high and other side effects to anyone else breathing it in, like with tobacco. Therefore, it is understandable that you may have some worries about the health of those around you.

This can understandably lead to concerns for both users and non-users. However, it should be noted that it is very unlikely that you can get a contact high just by being near someone. There are other factors that come into play, which we will cover later on.

A group of people smoke weed at a party; can their cannabis consumption cause contact concern? By monkeybusinessimages via iStock
Photo Credit: monkeybusinessimages via iStock

Is It Possible to Get a Contact High?

Whether a contact high is a real phenomenon is still widely debated, with research studies drawing different conclusions. As mentioned, there are also additional components that could influence the chances of a contact high.

A study (

) by the Health Hazard Evaluation Program found that although small amounts of THC were found in 34% of participants who were exposed to secondhand smoke, it wouldn’t be enough to cause them to fail a drug test.

On the other hand, a

earlier study by Edward J. Cone et al. from John Hopkins University found that when placing six smokers and six non-smokers in a poorly ventilated room, there was the chance the marijuana smoke could trigger a positive test for the non-smokers who had inhaled the secondhand smoke. That being said, the inaccurate positive result decreased rapidly with time.

With this in mind, it could be that the possibility of getting a contact high is determined by the proximity of the non-users to the user as well as the level of ventilation in the area.

For example, if non-smokers and cannabis smokers are together in a small room or a car without the windows being down, the non-smokers are likely to be more susceptible to the effects. However, if a non-smoker smells marijuana when walking down a high street, they’re unlikely to feel any effect.

Can Dogs Get a Contact High?

Being around animals and children can be a concern for cannabis smokers who obviously want to keep them safe from the smoke’s effects; this is why it is especially important to keep your cannabis products out of reach in case your pet or young child tries to consume them.

Dogs in particular have more

cannabinoid receptors than humans – your pet dog will likely be able to feel the effects of marijuana if it ingests it or is inhaling secondhand marijuana smoke, and can be more hazardous in their system. The effects can be very distressing for your dog, and it can potentially become sick – therefore, we strongly advise that you take responsibility and care when you’re around animals and children.

Mistakes do happen, and your dog may find its way to your product, so there are some signs you can look for in the event that your dog has consumed your cannabis product. These include the following:

  • Dilated pupils
  • Being easy to startle
  • Instability
  • Drooling
  • A low blood pressure
  • Vomiting

If you think your dog has gotten high, make sure to take it to your veterinary specialist as soon as possible after recognizing the signs. Though chances of death from marijuana consumption itself are fairly low, restricted breathing, fainting into vomit, and physical weakness in your pet can all lead to injury or worse; for them, the act of getting high can be more like getting drunk for a human, with all of the potential risks and dangers that entails.

Can Cats Get a Contact High?

If you are a cat owner, you may think cannabis is another version of catnip, but they have some big differences. Cannabis derives from the Cannabis Sativa plant, whereas catnip is a very different type of herb that makes cats become hyperactive if they smell it or tired if they eat it; catnip doesn’t work on humans the same way it does felines.

There are not enough studies looking at the effects of cannabis on cats and dogs, so it is advised you keep marijuana away from them. Be especially mindful if your cat has underlying respiratory conditions such as asthma.

Once again, mistakes do happen as your cat may find and consume a cannabis edible, for example. If you suspect this has happened, look for these signs in your cat:

  • Dilated pupils
  • Lack of coordination
  • Vomiting
  • Low blood pressure or heart rate
  • Seizures

As above, if you notice any of these signs in your pet cat or dog, be sure to take them to your veterinarian as soon as you can.

A man exhales a cloud of vapor, by Lorend_g via Pixabay
Photo Credit: Lorend_g via Pixabay

Contact Highs: Smoking vs Vaping

You might be wondering whether vaping cannabis is a way to avoid any potential contact highs. Although

into the atmosphere, it won’t remove them completely.

Since a vape does not burn freely like a joint, there are no cannabinoids being released when the user isn’t inhaling. The only way cannabinoids get into the air is when the user exhales vapor that hasn’t been fully absorbed. However, another human would have to be standing close enough to the vape to essentially be hitting it themselves to truly get the effects of cannabis.

If you want to consume marijuana with no threat of contact highs whatsoever, then eating edibles is the best thing to do. The only way someone can get high from an edible is by actually ingesting it.

How Long Are Cannabinoids Active in Secondhand Marijuana Smoke?

As noted in a review article by the British Journal of Anaesthetics (

), only 50% of THC and other cannabinoids are inhaled through mainstream smoke. However, if the smoker inhales deeply and waits a few seconds before exhaling, then almost all of the cannabinoids will enter the bloodstream.

This means you would have to be under extreme conditions to feel any effect from the THC. Even then, the effects would most likely only be minor.

As previous research has suggested, to feel the effects of secondhand marijuana smoke requires close proximity to the smoker and being in a room with poor ventilation for some time.

The Edward J. Cone et al. study found that the non-smokers who faced marijuana secondhand smoke exposure for an hour in a poorly ventilated room did test positive for having THC in their system.

The chances are that under typical circumstances, the psychoactive cannabinoids would have disappeared long before they reached the non-smoker.

What Are the Side Effects of Secondhand Marijuana Smoke?

It is important to note that there currently isn’t enough research to deduce exactly how secondhand marijuana smoke compares to secondhand tobacco smoke.

That being said, it is urged that you are courteous of those around you, especially regarding children and animals, as those who are subjected to secondhand cannabis smoke can experience side effects even if not directly trying to get high. These can include:

  • Headaches
  • Irritated eyes, whether that’s redness, burning, or itching
  • A dry mouth
  • Coughing
  • Dizziness
  • Nausea
  • Tiredness
  • Anxiety

Therefore, even if the associated effects of secondhand exposure to marijuana smoke are low, we urge you to be respectful of those around you.

Exposure to Secondhand Marijuana Smoke – Health Risks

As well as side effects, there are some health risks to be aware of that may affect those who are exposed to secondhand marijuana smoke.

All smoke is harmful to the lungs, whether that is from cannabis smoke, tobacco, or even burning wood. According to the American Lung Association, inhaling marijuana smoke

cause lung irritation and symptoms such as wheezing, acute bronchitis and chronic coughs.

Therefore, take responsibility if you are around those with respiratory conditions such as asthma and bronchitis, who may be more vulnerable.

As mentioned, there is not enough long-term research to fully identify the effects of secondhand marijuana smoke.

However, a

by Xiaoyin Wang et al., published in the Journal of the American Medical Association, found that when rats were exposed to secondhand cannabis smoke for one minute, they experienced dilated blood vessels and low blood pressure for at least 90 seconds.

The researchers deduced that secondhand smoke produces adverse cardiovascular effects, regardless of whether it is from marijuana or tobacco.

Can a Contact High Show on a Drug Test?

As we’ve touched on, when marijuana smokers exhale, there is a minimal amount of THC given out. Therefore, it would take a prolonged amount of exposure to feel the effects of the smoke and fail a drug test.

As the study by the Health Hazard Evaluation Program found, the level of THC consumed second-hand was not enough to cause the participants to fail the test, and like Edward J. Cone et al.’s research found, the participants who did trigger a positive test result were in a room with little ventilation and in close proximity to the smokers for a prolonged period; as noted, the levels of THC in your system would only be present for a short time after.

Overall, it is under unlikely circumstances that someone who has been exposed to secondhand smoke would fail a test. This is unless they have been in an airless room for a reasonably long time and in close proximity to the smokers. In this situation, they would also be taking the test around an hour after the exposure.

The Studies Done on Secondhand Highs

We’ve covered several studies so far relating to the effects of secondhand marijuana smoke. Unfortunately, due to some states only recently making cannabis legal, there are only a few studies exploring the impact of secondhand highs.

According to the mentioned 2015 study by Johns Hopkins University School of Medicine, secondhand marijuana smoke can cause non-smokers to feel the high effects, but only under “extreme conditions.”

The findings mirror some of the other studies we’ve looked at by the non-smokers only feeling the effects when in stuffy rooms or enclosed spaces such as cars. They found that these people would only experience minor effects, such as with their coordination.

A puff of smoke in the air, by hobo_018 via iStock
Photo Credit: hobo_018 via iStock


Can you get high from smelling or touching weed?

This will depend on many factors, which are unlikely to accidentally happen at the same time. Firstly, to feel the effects of secondhand marijuana smoke, you need to be at least relatively close to the person smoking; if all the smoke has dissipated, your odds of experiencing second-hand effects are very slim.

Secondly, you’d need to be in an enclosed space with poor ventilation, such as a car with the windows rolled up or a small bedroom with the windows and doors closed. Then, you’d need to be exposed to the smoke for a prolonged period of time.

If you walk by someone and smell marijuana, this will not be enough to induce any of the associated effects. In short, you are very unlikely to feel the high sensation without purposefully trying to.

How long does vape smoke stay in the air?

Firstly, particles from a standard cigarette have been found to linger for two to three hours after finishing it. However, according to a

exploring the differences between exhaled e-cigarette mist and cigarette smoke, vape smoke disperses within seconds.

The study explored different room ventilation conditions and found that the particles still disappeared very quickly, even in less ventilated spaces.

Is secondhand CBD smoke safe?

Unlike conventional cannabis,

, which are what causes the psychoactive effects marijuana use is known for.

While CBD is safer in protecting others from the mind-altering effects, the vapor itself can still be harmful to those with respiratory conditions like asthma and bronchitis as the smoke can still irritate their lungs.

As for the user, CBD smoke can cause dry mouth, drowsiness, and reduced blood pressure. Likewise, be mindful of the vape juices you are using, as they can contain other chemicals.

Therefore, CBD on its own is a safer alternative to smoking marijuana, but you should still be considerate of others.

Wrapping Up

There are numerous reasons why one may be concerned about the possible risks associated with secondhand marijuana smoke. If you’re a smoker, you may want to know the impact it may have on your pets or children. If you’re a non-smoker, you may want to know about the health effects and whether breathing the smoke can affect you.

Research into the effects of marijuana smoke is still in its infancy. Still, so long as you are taking responsibility, being careful, and being conscious of those around you, the impact of secondhand exposure should be minimal.

No matter what: We strongly recommend that if you smoke marijuana, you are considerate of those around you.

We hope this article has been helpful in answering your questions and concerns surrounding secondhand marijuana smoke.

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