High Alert is seeing an increase in harm from synthetic cannabinoids. In the past, synnies have been linked to deaths in New Zealand and overseas. Read more here.

Key things to know

They were initially created to work on similar parts of the brain as cannabis, but their effects can be much more dangerous and unpredictable

What to expect

There are many different types and strengths. They are usually made by spraying chemicals onto plant material

Drug differences

Different parts of the same bag could have different strengths, putting you at risk of an overdose


Use a smaller amount and wait to see the effects, this can reduce your chances of overdosing

Safer using

Try to have a sober person that can help you if something goes wrong


How do synthetic cannabinoids make you feel?

It is important to keep in mind that there are many different types of synthetic cannabinoids, and while they share many effects, there are also lots of differences between them. Some synthetic cannabinoids like MDMB-4en-PINACA and AMB-FUBINACA are much more likely to cause serious harm or death than others.

How fast the effects come on and how long they last varies greatly depending on which type, how it is taken and how your body processes it. Many people say that the high from synthetic cannabinoids is very short lived, sometimes less than 30 minutes.

Remember, a low dose for one person can be a high dose for another as people’s bodies process drugs differently. 

Also keep in mind that, when mixed with alcohol or other drugs, synthetic cannabinoids can have different and more unpredictable effects to those listed below.

A medical responder on Reddit talks about his experience of picking up a man who was high on synthetic cannabinoids:

“I was having a lot of difficulty communicating with the guy (obviously), and I couldn’t get him to focus on any of my questions.. He was also on the fastest emotional roller coaster I’ve ever seen. Crying, laughing, I’m his best friend, etc.”

Pleasant effects

Unpleasant effects




Giggly or giddy


Socially confident

Pleasant sleepy feeling



Drowsy or groggy


Difficulty concentrating



Irritable or agitated


Mood swings

Pleasant effects

Unpleasant effects

Increased euphoria

Hallucinations (this may be a desired effect for some people)


Racing thoughts


Unpleasant hallucinations

Difficulty speaking

Difficulty moving your body

Severely dizzy or faint

Severely nauseous


Depersonalization or Dissociation 

Feeling panicked or having panic attacks

Fast or irregular heartbeat

Pleasant effects

Unpleasant effects


Foaming at the mouth

Chest pain

Difficulty breathing

Temporary paralysis


Intensely paranoid

Severe panic attacks



Losing consciousness (known as ‘dropping’)

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How can you be safer when using synthetic cannabinoids?

Synthetic cannabinoids are a big group of chemicals and some are more dangerous than others. It can be difficult to predict how they will affect someone, as different types of synnies can affect people differently.  It is always a good idea to think about the things you can do to be safer when using synthetic cannabinoids. 

Avoid mixing synnies with alcohol and other drugs. 
Synthetic cannabinoids come with the risk of ‘dropping’ or losing consciousness quickly, so try to avoid taking them with alcohol, other drugs or medicines (prescription or over the counter). Doing this can further increase the chances of having serious effects or overdose.

Use a smaller amount. 
In New Zealand there is no easy way for people who use synnies to test them reliably.  As these drugs are hard to test, it is important to start by using a small amount and waiting to see the effects. Starting with a lower dose can reduce your chances of overdosing or dropping. Even if you have used some of the synnies from the same baggie, the chemicals are often unevenly spread. This means one dose from the same baggie can be much stronger than another. 

Avoid using alone and have a sober buddy. 
As these drugs have been linked to many deaths in New Zealand and overseas, it is a good idea to have a ‘spotter’ or a sober person around you when you use. This person can get you help quickly if something bad happens.

Keep up to date with the latest information about dangerous synnies in NZ. 
You can follow High Alert to receive alerts and notifications about particularly dangerous batches of synthetic cannabinoids in New Zealand. You can also report any unusual effects you experience from synnies to High Alert. 

Consider not smoking synnies with tobacco or in vapes, bongs and pipes. 
You may want to consider avoiding smoking ‘spliffs’ of synthetic cannabinoids mixed with tobacco. Regular use of tobacco can lead to nicotine addiction and can damage your body. Be cautious when smoking synthetic cannabinoids in vaporisers, bongs or pipes as it can be easy to inhale too much. It is better to smoke in a joint (rolled up in paper).

For more information on how to be safer when using drugs and alcohol, see Safer using

To order self-help workbooks and other free resources for safer use, see Resources.

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What happens if you overdose on synthetic cannabinoids?

Your risk of having a bad experience on synthetic cannabinoids varies a lot depending on what type of the drug you take, how much you take and your individual body. Synthetic cannabinoids are unpredictable and can be easy to overdose on.

You might feel drowsy or confused, have difficulty concentrating, feel dizzy, sweat or feel hot, have trouble moving your body, feel nauseous, feel anxious or agitated, have mood swings or panic attacks.


  • Focus on breathing – try taking slow, deep breaths.
  • If you are able, call and talk to somebody you trust and ask them to help keep you calm.
  • Do not take more synthetic cannabinoids, caffeine, alcohol or other drugs, as these can make you feel worse.
  • Move to somewhere quiet – try to sit or lie down and do something relaxing.
  • Drink water to stay hydrated.

If you have a fever, are experiencing severe mental distress including anxiety, dissociation or paranoia, have difficulty speaking, vomit or have a fast or irregular heartbeat, call a doctor or Healthline (0800 611 116).

If you foam at the mouth, have a high fever, have chest pains or difficulty breathing, experience temporary paralysis, experience psychosis, have a seizure or a stroke or you lose consciousness, these are signs of an overdose. You or the people around you should act quickly. Call 111.

If you experience unexpected or concerning effects from synnies you can notify High Alert to help keep others safe.

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What do comedowns from synthetic cannabinoids feel like, and how can you feel better?

The comedown from synthetic cannabinoids can be very different depending on which type of the drug you have taken and how much.

If you're coming down from synnies, you may: feel anxious, irritable, agitated or restless. You might feel unmotivated or tired. You could have mood swings or difficulty sleeping. You might not feel hungry, or you might have nausea or diarrhea. Physically, you could sweat or feel hot, have leg pains, have a tight chest or have aches and pains. You might have cravings for more synnies. 

You can try...

  • Get plenty of rest and sleep.
  • Remember to eat and drink plenty of water.
  • Get moving to release feel-good brain chemicals.
  • Reach out and talk with friends and whānau for support.
  • Relax and do things that you enjoy to take your mind off not feeling well.
  • Avoid caffeine, alcohol and other drugs.
  • Practise mindfulness and deep breathing, and try writing down your thoughts and feelings.

If any of these symptoms intensify or don't go away then call a doctor or Healthline 0800 611 116. They can talk you through the next steps.

If  your symptoms worsen or you are with somebody who: 

  • Experiences psychosis
  • Attempts suicide
  • Has violent thoughts
  • Has chest pain
  • Has difficulty breathing
  • Has a seizure
  • Becomes unresponsive
  • Loses consciousness

Call 111. These are signs that something more serious is going on. You or the people around you should act quickly.

 A Reddit user talks about what happens when he stopped smoking the synthetic cannabinoid K2:

“The withdrawal was even worse because without smoking K2 in the same day I wouldn’t be able to swallow my food because I felt so nauseous all the time and kept gagging all my food up and I would throw up yellow bile.”

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What are the long-term effects of synthetic cannabinoids?

Synthetic cannabinoids can be addictive, and many people who use these drugs say that it can be difficult to stop taking them once you have started to use regularly. These drugs are hard to research as they are ever-changing, but evidence shows that they can have long-term impacts on the brain including memory, emotional regulation and increased likelihood of developing schizophrenia and depression.

Long-term use can also cause people to become severely paranoid (feeling like people are out to get you) and can lead to psychosis or psychotic behaviour (losing touch with reality). People who use these drugs regularly can become severely agitated, delusional, anxious or violent.

We don't know as much about the physical effects of long-term use. Smoking or inhaling any substance can damage your lungs, throat and mouth, and synthetic cannabinoids have been found to cause lung problems in some people who use regularly. Research also suggests that regular use of these drugs can cause kidney problems and damage, seizures and heart issues.

Because synthetic cannabinoids are not well researched and there are so many types of them available, there are likely to be many other long-term effects of these drugs that we do not yet understand.

How do you manage withdrawal from synthetic cannabinoids?

See the 'Making changes' page for more information on how to Manage withdrawal from drugs and alcohol.

Synthetic cannabinoids can be addictive. Many people experience unpleasant withdrawal symptoms when they decide to stop using them or take a break. How quickly withdrawal symptoms start and how long they last can depend on things like how much you use, what kind of synthetic cannabinoid you used and how long you used for.

Generally, symptoms of withdrawal start 1–2 days after you last used and can last for several weeks. People who use these drugs heavily and often may find that withdrawal symptoms start very quickly after they last used (in a matter of hours). For some people, the cravings for synthetic cannabinoids can last for several months after stopping.

You might: 

  • Have difficulty concentrating or difficulty sleeping
  • Feel irritated, agitated, jittery, anxious, paranoid or low
  • Have cravings to use synnies
  • Have aches and pains, headaches, weakness in your body, sweats or a cough

Try these things at home:

  • Follow a tapering plan from a health professional to reduce your dose slowly
  • Consider counselling or support groups if feelings of anxiety and depression are getting worse
  • Lean on a support network of friends, family and professionals
  • Stick to a routine – waking up, eating well, keeping active and rewarding yourself with things that bring you joy
  • Practise mindfulness by writing down your feelings, doing breathing exercises or meditating

If your symptoms get worse, or if you: have a fast or irregular heartbeat, have disturbing hallucinations, have ongoing insomnia, have tremors or suicidal thoughts, call a doctor or Healthline (0800 611 116).

You can talk to your doctor about:

  • other medicines to help you get through withdrawal
  • rehab or withdrawal clinics in your area – visit Health Point to see what services are available.

If you or someone you're with has chest pains or difficulty breathing, experiences delusions or psychosis, has signs of heart attack or stroke (such as numbness on right side or slurred speech), has a seizure, becomes unresponsive, loses consciousness, acts violently or attempts suicide, call 111. These are signs that something more serious is going on. You or the people around you should act quickly.

For more information on getting support for drug and alcohol use, see Finding support.

A Reddit user talks about using the synthetic cannabinoid K2 for several months and how he felt when he stopped:

“So I’ve been using a ‘THC’ vape juice that I got from a dealer for the past 3 months daily, I was under the impression that it was THC. Turns out it was spice, the withdrawal is killing me, anxiety is through the roof, diarrhoea and vomiting daily. And on top of that, migraines and a lack of energy.”

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How can synthetic cannabinoids affects your daily life?

Synthetic cannabinoids can affect your everyday activities. There is not a clear window of when these effects start and how long they last for, so it can be hard to predict when you will start to feel normal after using. If you use these drugs once, you are likely to be impaired during the high and comedown. If you use these drugs often, you may experience impairment in your day-to-day life, even when you are not high.

Synthetic cannabinoids can cause poor coordination, changes in perception, tremors, shakes and poor decision making, so it can be unsafe to drive, operate heavy machinery or do tasks that require fine motor skills. This group of drugs can also cause people to lose consciousness quickly and unexpectedly, making it very dangerous to work in high-risk environments (like building sites) while high. Synthetic cannabinoids can also make you feel paranoid, cause slurred speech and make it hard to remember things, which means that interacting with others can become very difficult.

Over the long term, synthetic cannabinoids can cause changes to your brain that affect your ability to remember new information and process emotions. These drugs can also increase your risk of developing schizophrenia and depression, which can affect your daily life. This may make it harder to carry out work or other social activities.

If you take synthetic cannabinoids, will it show up on a drug test?

Like many synthetic drugs, synthetic cannabinoids change often in how they are made and what is in them. This can make them harder to test for than drugs like cannabis. Synthetic cannabinoids could be tested for in hair, urine, saliva (spit) or blood but may not be tested for in routine drug tests, as testing methods are not very reliable.

The testing windows for these drugs can vary depending on what type of synthetic cannabinoid you used, how long you have used it for, how much you used and your individual body. Generally, it is thought that these drugs can be detected up to 48 hours in urine and saliva, from a few hours to a few days in blood and up to 90 days in hair (but there is some debate on how reliable this is).

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Are synthetic cannabinoids illegal?

Synthetic cannabinoids used to be legal to buy and use in New Zealand if you were over 18. However, they are now illegal, two of which (AMB-FUBINACA and 5F-ADB) are Class A controlled drugs in the Misuse of Drugs Act. These drugs are illegal to buy, sell, possess or import in New Zealand. Other synthetic cannabinoids that are analogues of AMB-FUBINACA and 5F-ADB are Class C controlled drugs under the Misuse of Drugs Act. Any other synthetic cannabinoids are illegal to buy, sell, possess or import under the Psychoactive Substances Act,  but come with different penalties.

You can also get in trouble with the law if you are found to be impaired by synthetic cannabinoids while driving.

To find out more about the law around drugs synthetic cannabinoids and the Psychoactive Substances Act, see Drugs and the law.

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