The Dangers of Synthetic Weed (K2/Spice)

As more states across the U.S. legalize cannabis, dangerous synthetic forms of the drug have also become more widely available. Synthetic weed, also known as K2 or Spice, is a chemically made product that’s meant to mimic the effects of cannabis on the body. People often think it’s a safe alternative to cannabis. But these products can be dangerous and cause serious health issues.

What is synthetic cannabis (fake weed)?

Synthetic cannabis refers to chemicals made in a lab that are designed to act on the same receptors (binding sites) in the body as THC and CBD — two active ingredients of the cannabis plant. These chemicals are often sprayed on dried, ground plant material so they look like cannabis. The chemical-soaked plant is then smoked or brewed as a tea. They’re also sold in liquid form to use in e-cigarettes or vape pens.

Synthetic cannabis is often sold as incense or potpourri, and may even say “not for human consumption” on the packaging. But often, the packaging uses names like “Scooby Snax” or “Skunk,” along with colorful designs that mislead people into thinking they’re the same as products made from the cannabis plant.

Good to know: There are also FDA-approved medications, such as dronabinol (Marinol), that contain synthetic cannabinoids. These synthetic cannabinoids went through a full drug-approval process that involved clinical studies on their safety and effectiveness. So they aren’t the same as the illegal synthetic cannabis products discussed here.

What are the dangers of synthetic weed?

Even though synthetic cannabis may affect the same receptors as the cannabis plant, the effects aren’t the same as natural cannabis. These lab-made chemicals can be much stronger than natural cannabis. And they aren’t tested or regulated, so there’s no way of knowing if they’re even safe for human use. Not to mention, there’s a possibility that these products could contain other substances, such as fentanyl or rat poison. People have died after using synthetic cannabis products with these hidden ingredients.

Additionally, studies show that regular use of synthetic cannabinoids can cause permanent changes in the body. Researchers found an association between long-term use of synthetic weed and problems with attention and memory. Heart disease and kidney disease may also be linked to long-term use. Also, people who repeatedly use synthetic cannabinoids are more likely to develop psychiatric conditions such as depression, anxiety, and schizophrenia.

Synthetic cannabis products may also be more likely to cause dependence than natural cannabis products. This can lead to more severe withdrawal symptoms, which can make it harder for you to stop using these products.

If you or someone you know struggles with substance use, help is available. Call SAMHSA’s National Helpline at 1-800-662-4357 to learn about resources in your area.

Synthetic weed side effects

Synthetic cannabinoids act on the same receptors as natural cannabis. So they may cause the same euphoric feeling or “high” at first. But since they bind receptors with a greater strength, that high can quickly turn unpleasant. And synthetic cannabis can also cause additional side effects that natural cannabis doesn’t.

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Possible side effects from synthetic cannabis use include:

• Anxiety

• Agitation

• Nausea

• Vomiting

• Dizziness

• Drowsiness

• Fast heart rate

• Tremor

• Confusion

• Seizures

• Hallucinations

• Stroke

• Muscle damage

• Kidney damage

• Heart attack

If you or a loved one have side effects like these after using a synthetic cannabis product, seek emergency care right away. If possible, bring the product to the ER with you. Medical staff may be able to test it to determine how best to help you. 

Synthetic weed vs. weed: Can you tell if weed is synthetic?

You probably can’t tell by looking if a product contains synthetic cannabis chemicals. As mentioned, they’re often sprayed onto plant material and marketed as “natural” products. And the package labeling isn’t regulated, so it’s unlikely you can trust the label to tell you exactly what’s inside the product you’re purchasing.

Tips to avoid synthetic weed

The best way to avoid synthetic cannabis is to only purchase state-regulated cannabis products from licensed dispensaries. These cannabis products typically require thorough testing and must adhere to strict labeling requirements. So you can trust that they only contain what the label shows.

Products sold at unlicensed head shops, bodegas, or gas stations are much more likely to contain harmful or illegal substances. It’s best to use caution when purchasing products from locations like these. And if a product indicates that it’s “not for human consumption” — that’s a giant red flag to steer clear.

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Written by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

Reviewed by:

Sarah Gupta, MD

Sarah Gupta, MD, is a licensed physician with a special interest in mental health, sex and gender, eating disorders, and the human microbiome. She is currently board certified by the American Board of Psychiatry and Neurology.

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