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Class: Psychoactive Substances

Synthetic cannabinoids, commonly known as “Spice” or “K2,” are designed to emulate the effects of Δ9-tetrahydrocannabinol (THC), the psychoactive ingredient found in cannabis. They first gained attention in the early 2000s and were initially marketed as legal alternatives to cannabis.

Also called:

K2 Synthetic Cannabinoids Synthetic Marijuana Yucatan Fire Skunk Moon rocks Black Mamba Bliss Bombay Blue Genie
How the drug works varies from person to person

How you might feel

Initial feelings of relaxation and euphoria can quickly turn into extreme anxiety, confusion, and hallucinations.

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Effects on your body

 May lead to heart palpitations, acute kidney injury, and seizures. Long-term effects are not well-understood.

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How long it takes to work

Effects typically manifest within minutes of smoking or vaporising.

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How long the effects last

Effects generally last several hours, but lingering effects like confusion can last for days.

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Common risks

Acute health risks include heart issues and kidney damage. Risk of overdose is high, and effects can be fatal.

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Synthetic cannabinoids, commonly known as “Spice” or “K2,” are designed to emulate the effects of Δ9-tetrahydrocannabinol (THC), the psychoactive ingredient found in cannabis. They first gained attention in the early 2000s and were initially marketed as legal alternatives to cannabis.1 The compounds were originally intended for research purposes, often to explore the human endocannabinoid system, but they quickly found their way into recreational use.2

These substances were created for medical and research applications but were soon adopted for recreational purposes, often because they were inaccurately believed to be safer or less detectable than cannabis. They first emerged in the UK around 2004, sold under brand names like “Spice” and “K2”.3 The term “Spice” was originally a brand name but has since become a colloquial term for synthetic cannabinoids. In 2016, the UK made it illegal to produce, distribute, or sell these substances.4

The effects of synthetic cannabinoids can be unpredictable and potentially severe. These can range from feelings of euphoria to dangerous health outcomes like increased heart rate, hallucinations, and even death.5 Unlike cannabis, synthetic cannabinoids interact more completely with the brain’s cannabinoid receptors, leading to much more potent effects, including extreme anxiety and paranoia.6 These substances can also appear in various forms, such as dried plant material sprayed with synthetic chemicals or as liquids to be vaporised and inhaled.7

How it looks, tastes and smells


Synthetic cannabinoids like “Spice” or “K2” can appear in various forms, often resembling herbal tobacco or even potpourri. The most common form is a greenish-brown dried plant material that has been sprayed or soaked with synthetic cannabinoid chemicals. The substances can also be found as liquids to be vaporised and inhaled in e-cigarettes or other vaporising devices.7


The taste of synthetic cannabinoids can differ depending on the specific chemicals and base plant material used. However, users often report that it has a harsh, chemical taste, which can be quite unpleasant. The taste is generally considered to be less natural than that of organic cannabis.


The smell of synthetic cannabinoids also varies, but it generally has a chemical odour that can differ significantly from the scent of natural cannabis. Some preparations may include flavourings or aromatic herbs to mask the chemical smell, leading to a wide range of possible odours. However, most formulations will have an artificial, sometimes pungent aroma.7


It’s crucial to note that the potency and effects of synthetic cannabinoids can vary widely between different products and batches, making it difficult to establish standard dosage guidelines. The compounds are often far more potent than natural cannabis, and even a small amount can produce strong or unpredictable effects.6

  • Minimum to Feel Something: Due to the unpredictability and varying potency of synthetic cannabinoids, there is no universally agreed upon minimum dosage in milligrams to feel effects. Some reports suggest that even a few milligrams can produce noticeable effects.2
  • Low Dose: A low dose may consist of a few milligrams, although this varies widely due to the potency of the particular synthetic cannabinoid involved.
  • Common Dose: Given the varying concentrations of synthetic cannabinoids in different products, specifying a ‘common’ dose is challenging.
  • High Dose: A high dose can also be a matter of a few milligrams, depending on the specific compound and individual tolerance. High doses can lead to severe or even life-threatening effects like organ damage, extreme hallucinations, and heart issues.5

Notes on What May Happen When Exceeding High Dose:
Exceeding a high dose of synthetic cannabinoids can lead to severe or life-threatening outcomes. Users may experience acute kidney injury, heart palpitations, seizures, hallucinations, and, in extreme cases, death.5, 6

How you might feel

Users may initially report sensations of relaxation, euphoria, and altered perception. However, the effects can quickly become unpleasant, leading to extreme anxiety, paranoia, confusion, and hallucinations. The experiences are highly unpredictable and can vary from one user to another.6

How long it takes to work

The effects of synthetic cannabinoids often manifest rapidly, generally within minutes after smoking or vaporising. The quick onset is one of the factors that contribute to the drug’s unpredictability and potential danger.2

How long the effects last

The duration of effects can vary but typically last for several hours. Some users report lingering effects that may last for days, including mental confusion and anxiety.2

Common risks

The risks associated with synthetic cannabinoids are numerous and can include both short-term and long-term health issues. Short-term risks include heart problems, kidney damage, and neurological symptoms. The long-term risks are not well understood due to a lack of research but are believed to be significant.5,6


Synthetic cannabinoids like Spice or K2 are often misconceived as safer alternatives to natural cannabis; however, they have a high potential for abuse and addiction. The lack of quality control and variation in chemical compounds make it unpredictable and particularly hazardous.2

Many users report developing cravings and withdrawal symptoms, which are indicative of dependency.3 Problematic use can also manifest as repeated attempts to quit or cut down, sacrificing social activities, and persistent usage despite knowing the risks and experiencing adverse effects.6

Synthetic cannabinoids bind more strongly to the same receptors as natural THC, leading to more intense and longer-lasting effects, which can include severe agitation, paranoia, and hallucinations. This potency increases the risk of developing psychological dependence.9

Addiction to synthetic cannabinoids can be difficult to treat due to the limited research on the drug. However, behavioural therapies and support from trained healthcare providers have shown to be beneficial.10

The Law in the UK

In the United Kingdom, synthetic cannabinoids like “Spice” or “K2” are controlled under the Psychoactive Substances Act 2016. This act made it illegal to produce, distribute, sell, or supply these substances.4,8 Before this legislation, synthetic cannabinoids had been temporarily controlled under various drug laws but were often circumvented through slight modifications to their chemical structures. The 2016 act aimed to close these loopholes.4

In terms of classification, synthetic cannabinoids are not classified under the A, B, or C categories that traditional drugs like cannabis, cocaine, or heroin fall under. Instead, they are controlled under their specific legislation, which means penalties can vary from those of more traditionally classified drugs.8

Violations of this act can result in serious legal consequences. For instance, the production and distribution of synthetic cannabinoids can result in up to 7 years in prison, an unlimited fine, or both.4

Mixing Drugs

Mixing synthetic cannabinoids like Spice or K2 with other drugs or substances is strongly discouraged. Combining these substances can lead to serious and unpredictable health risks.

  • Alcohol: Mixing synthetic cannabinoids with alcohol can result in increased sedation and may cause dangerous respiratory depression.3
  • Cannabis: Combining with natural cannabis can lead to more unpredictable effects, increasing the risks of severe anxiety, paranoia, and hallucinations.2
  • Stimulants (e.g., Cocaine, Amphetamines): The use of synthetic cannabinoids alongside stimulants can significantly increase heart rate and blood pressure, potentially leading to seizures or heart issues.
  • Depressants (e.g., Benzodiazepines, Opiates): Taking synthetic cannabinoids with depressants increases the risk of respiratory failure and could lead to life-threatening sedation.6
  • Psychedelics (e.g., LSD, Magic Mushrooms): Mixing with psychedelics can lead to extreme hallucinations and psychological distress, heightening mental health risks.9

Given the severe and sometimes fatal outcomes associated with mixing synthetic cannabinoids with other substances, it’s advisable to consult healthcare professionals for proper guidance.


  1. Obama White House Archives. (n.d.). Synthetic Drugs (a.k.a. K2, Spice, Bath Salts, etc.). Retrieved from
  2. European Monitoring Centre for Drugs and Drug Addiction (EMCDDA). (n.d.). Synthetic Cannabinoids. Retrieved from
  3. NHS Inform. (n.d.). Synthetic Cannabinoids (‘Spice’). Retrieved
  4. (n.d.). Synthetic Cannabinoids, Salvia & ‘Spice’. Retrieved
  5. Drug Enforcement Administration (DEA). (n.d.). Spice, K2, Synthetic Marijuana. Retrieved
  6. National Institute on Drug Abuse (NIDA). (n.d.). Synthetic Cannabinoids (K2/Spice) Unpredictable Danger.
  7. Orlando Recovery Center. (n.d.). What Does Spice Look Like? Retrieved from Orlando Recovery Center.
  8. Commons Library. (2018). New Psychoactive Substances. Retrieved from
  9. The Conversation. (2016).
  10. Rehab Guide. (n.d.).

What people ask

Synthetic cannabinoids are a type of designer drug intended to mimic the effects of THC, the active ingredient in cannabis. However, their effects can be much stronger and more unpredictable.

They are often sprayed onto plant material and smoked, similar to cannabis. They can also come in liquid form, which is used with e-cigarettes or other vaping devices.

The drug typically looks like dried herbs or plant material, sometimes resembling potpourri. The liquid forms are usually colourless and odourless.

Initial effects may include feelings of relaxation and euphoria. However, the drug can quickly produce negative effects like extreme anxiety, confusion, and hallucinations.

Effects can last several hours but vary widely depending on the specific substance and the dose. Lingering effects like confusion can last for days in some cases.

Taking a high dose can lead to severe health consequences like heart palpitations, acute kidney injury, and seizures. In extreme cases, overdose can be fatal.

Yes, synthetic cannabinoids have a high potential for abuse and addiction. Withdrawal symptoms include cravings, nightmares, and tremors.

In the UK, synthetic cannabinoids are controlled under the Psychoactive Substances Act of 2016. It is illegal to produce, distribute, or sell these substances.

Production and distribution can result in up to 7 years in prison, an unlimited fine, or both.

It is highly discouraged to mix synthetic cannabinoids with other substances, especially central nervous system depressants like alcohol, as it can lead to dangerous interactions, including respiratory failure.

While they are designed to mimic the effects of cannabis, synthetic cannabinoids are chemically different and can be much more potent and dangerous.

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