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How to tell if your cannabis is laced

How to tell if your cannabis is laced

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Laced weed is another way to describe cannabis that has been altered with another substance. 

Despite what sensationalist headlines would have you believe, verifiable cases of laced cannabis are exceedingly rare.  

If you’re reading this article in a post-smoking panic – take a deep breath. It is possible the anxiety and worry you’re experiencing is from the THC itself, not a contaminant. Now take another couple deep breaths and have a bite of a snack or a sip of drink.

While examples of laced cannabis are rare, it has happened and the dangers can be real.  

What does laced weed look like?

It can be hard to tell if your cannabis is laced by looking at it, if not impossible. Some substances will change the odor or the appearance of the bud, while others won’t leave a trace. Avoid any cannabis that looks like it has been powdered, dusted, coated or sprayed. If your bud smells strange or harsh, like chemicals, it may have been laced or contaminated.

Of course, discerning what has been sprayed or powdered on cannabis flower can be difficult to the untrained eye. Because cannabis has a pungent odor, often even described as gas, diesel, or fuel, not everyone will be able to identify an abnormal odor. And because cannabis can naturally appear to be covered in crystals due the the resin-filled glands on the outside of the flower – the trichomes – the average consumer may not be able to distinguish them from powder or sprayed on chemicals. 

But smell and appearance can’t catch everything and the only sure way to tell if cannabis has been laced is with a series of laboratory tests. If you’re unsure about the quality of your cannabis or suspect for whatever reason that it may have been laced, err on the side of caution and throw it out – even if it hurts! 

What could weed be laced with? 

There are a number of substances that weed could be laced with. 

It’s important to remember that it’s rare to come into contact with laced weed, even on the illegal market. People sell drugs to earn a profit, not to harm people.The practice of mixing in harder drugs like opiates with weed is quite uncommon because these harder drugs are inherently more profitable than cannabis. Therefore, unless the dealer is openly selling laced cannabis at a higher markup, there would be very little economic incentive to lace weed with hard drugs. This is not to say that it doesn’t happen, but simply that this is not a common business tactic; and given the risks of consuming laced weed (which can include death), this can even put drug dealers at risk of being prosecuted for selling tainted drugs. 

Substances include: 

  • Opioids
    • Fentanyl
    • Heroin
  • Stimulants
    • Cocaine
    • Crack
    • Methamphetamine
  • Psychedelics drugs
    • LSD (Acid)
    • PCP (Angel dust)
    • Ketamine
  • Other substances (aka contaminated)
    • Crushed glass
    • Laundry detergent
    • Food coloring
    • Embalming fluid 1

Can edibles be laced?

Yes, edibles can also be laced. In April of 2022, a woman in the United Kingdom died after eating a gummy made from synthetic cannabinoids. If you suspect you or a friend has ingested laced edibles, contact emergency services. 

However, it’s important to note that a high-dose of THC infused edibles can also cause intense experiences. High doses of THC can have intensely unpleasant (but not fatal) side effects including anxiety, paranoia, vomiting, shortness of breath and overall discomfort. Some people who green out on THC even report thinking they “were going to die.”  

Symptoms of having smoked laced weed

Symptoms of having smoked laced weed will depend on what other substance was in the bud. 

Assuming you know what it feels like to be high, remember that high levels of THC can cause anxiety and paranoia. These symptoms are normal and somewhat common with weed. But if you notice other abnormal symptoms like chest pain, passing out, slurred speech, profound sedation or hallucations, seek medical attention and consider tossing the weed if there is no other explanation for these symptoms. 

Of particular concern are side effects typically associated with opioid use rather than cannabis. The World Health Organization defines three symptoms of an opioid overdose:

  • pinpoint pupils
  • unconsciousness
  • reduced, shallow breathing (known respiratory depression)

If you notice these symptoms in anyone after smoking cannabis, contact emergency medical professionals. 

Additionally, it is rare that cannabis causes visual and auditory hallucinations, and experiencing these during a THC-induced high may suggest laced weed, or it could be related to an underlying risk of experiencing psychosis. In this case, it is best to avoid THC and discuss this experience and alternatives to cannabis with a health professional. 2

How to avoid laced weed

Knowing where your weed comes from is the best way to avoid laced weed (Shutterstock)
  • In the legal market, you can usually request a COA (certificate of analysis) to see the lab test results for your flower, prerolls, and edibles. 
  • If you don’t have access to the legal market, get to know your source. Are you buying from the grower themselves or someone else down the supply chain? 
  • Avoid pre-ground weed if you don’t know your source, as it can be easier to lace than whole buds.
  • Trust your instincts. If you suspect for any reason your bud has been tampered with, throw it out. 
  • Always try a small amount of any new cannabis before diving in, especially if it was bought from an unknown source.
  • Grow your own. There is no better way to know that weed is grown right and clean than doing it yourself

Bottom line 

There’s no foolproof way to tell if your weed is laced. The easiest way to avoid it grow your own bud or get a COA on legal cannabis products. But this isn’t always possible, so it’s important to be aware of the rare but potential risks. Consume cannabis mindfully and avoid products when you don’t know where they’re coming from. Monitor your dosage when trying new products and remember don’t freak out; cases of laced cannabis are few and far between. 


  1. Hawkins KA, Schwartz-Thompson J, Kahane AI. Abuse of formaldehyde-laced marijuana may cause dysmnesia. J Neuropsychiatry Clin Neurosci. 1994;6(1):67. doi:10.1176/jnp.6.1.67b
  2. Wainberg, M., Jacobs, G.R., di Forti, M. et al. Cannabis, schizophrenia genetic risk, and psychotic experiences: a cross-sectional study of 109,308 participants from the UK Biobank. Transl Psychiatry 11, 211 (2021). https://doi.org/10.1038/s41398-021-01330-w
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