Synthetic cannabinoid toxicity (Spice): symptoms, risks and when to call 999

Synthetic cannabinoids are man-made chemicals designed to act on the same receptors in the brain as THC, the main active ingredient in cannabis. Talk to Frank explains that there are dozens of these chemicals and that they are different from natural cannabis even though they target the same receptors. Semi-synthetic cannabinoids are derived from cannabis but altered into chemicals that do not occur naturally.

The products come in several forms. Talk to Frank says that in their pure form they are solids or oils, which are often sprayed onto dried herbs or plant material to make smoking mixtures, and increasingly added to liquids sold for vaping or to sweets sold as edibles, sometimes called gummies. It says vape liquids containing them are commonly mis-sold as "THC liquids", and that the same goes for "THC gummies". The sweets may look the same as high street brands.

A systematic review in the research literature describes synthetic cannabinoids as emerging drugs of abuse sold as K2, K9 or Spice in herbal smoking mixtures, belonging to the group labelled new psychoactive substances. It reports that they have been associated with greater toxicity and higher addiction potential than THC, and that there is limited knowledge of the toxicology of the ingredients.

Talk to Frank says the chemical composition and ingredients of smoking mixtures change all the time, so you can never be sure what you are getting, how powerful it is or how it will affect you. Because of the way smoking mixtures are made, the concentration can differ between packets and between batches, and the mixing or spraying process can leave some of the plant material heavily coated and some barely coated. There is no way of knowing how strong a vape liquid will be.

It also notes that the plant material may be covered in a toxic substance such as a pesticide, or contain residues of solvents such as acetone and methanol used in the mixing and spraying process. Vapes bought from illegal sources have been found to contain these cannabinoids and have contributed to many overdoses in the UK, some resulting in hospital admission, according to Talk to Frank.

Talk to Frank lists reported side effects of synthetic and semi-synthetic cannabinoids. The systematic review in the research literature, which drew on 64 articles including 54 case studies, found tachycardia and seizures were the most common toxicity symptoms, and that fourteen studies reported deaths associated with synthetic cannabinoid use.

• Light-headedness, dizziness, confusion and tiredness.

• Feeling excited, agitated and aggressive, mood swings, anxiety and paranoia, and suicidal thoughts.

• Memory problems and amnesia.

• Nausea and vomiting, hot flushes and excessive sweating.

• Increased heart rate and blood pressure, which Talk to Frank says may cause chest pains and damage the heart and even cause a heart attack.

• Numb and tingling fingers, toes or muscles, tremors, seizures and fits.

• Hallucinations and psychotic episodes, which Talk to Frank says can in extreme cases last for weeks.

Talk to Frank says that if you or someone else needs urgent help after taking drugs or drinking, you should call 999 for an ambulance and tell the crew everything you know. The NHS says to call 999 or go to A&E if someone has swallowed, touched or breathed in something harmful, has lost consciousness or stopped breathing, has severe difficulty breathing or has a seizure, and not to drive to A&E.

The NHS poisoning page also advises that while waiting for help you should start CPR if someone is unresponsive and not breathing, put them in the recovery position if unconscious but breathing, keep checking their breathing and try to find what may have caused the poisoning, taking the substance or its packaging to hospital if possible. It says not to try to make someone sick and not to give them anything to eat or drink.

Tell the ambulance crew about vapes, gummies or other products used, even if you are worried about getting into trouble; the clinical priority is to treat the person. Talk to Frank notes there have been deaths associated with these drugs, either alone or with other substances.

Talk to Frank says research suggests there may be an association between synthetic cannabinoid use and acute kidney injury, and that there is a suggested risk of overstimulating the serotonin system (serotonin syndrome), which can cause high fever, rapid pulse, sweating, agitation, confusion, convulsions, organ failure, coma and even death.

It says regular use can lead to dependence, and that people who use them regularly may find it difficult to stop and may experience psychological and physical withdrawal. Regular use could cause a relapse of mental health illness or increase the risk of developing a mental illness, especially with a family history of mental illness.

Mixing drugs, including with alcohol or other drugs, is always risky, and Talk to Frank says some mixtures are more dangerous than others. It also notes that some drugs are increasingly cut with dangerous synthetic opioids such as nitazenes, which it says have killed hundreds of people in the UK in the past year, and that you can never really know what is in any street or counterfeit drug.

Treatment of acute toxicity is supportive and delivered in hospital, aimed at the symptoms that develop, such as agitation, seizures and a very fast heart rate, as the NHS says poisoning needs hospital treatment because it can cause you to be seriously unwell and be life threatening. If you have no symptoms you may still need monitoring for several hours in case you become unwell, according to the NHS.

For people who want to cut down or stop, the NHS says you are entitled to drug treatment in the same way as anyone else with a health problem, that a GP is a good place to start and that you can also approach your local drug treatment service yourself. It describes treatment plans that may include talking therapies such as CBT, self-help groups, and harm-reduction support, with a keyworker to support you. Charities and the NHS provide most drug treatment, and private services exist for which you pay.

Because the law changes, it is worth knowing that Talk to Frank says synthetic cannabinoids not controlled under Class B of the Misuse of Drugs Act and semi-synthetic cannabinoids are subject to the Psychoactive Substances Act 2016.