Surge in cannabis-induced psychotic episodes across the UK as potency of strains has increased

Cannabis-induced psychosis is becoming increasingly common across the UK, a leading psychiatrist has warned.

The widely used class B drug – also known as marijuana or weed – can cause dependency, and, in the year to March 2024, 2.3million people in the UK reported using it.

But while regular use has more than halved in the past two decades, the number of cannabis-induced psychosis episodes has spiked as varieties on sale have become stronger.

Those experiencing a psychotic episode commonly have symptoms such as hallucinations, dissociation or unusual changes in behaviour. 

And while these resolve in most cases, side-effects can last for years. 

Studies show cannabis can even trigger schizophrenia – a chronic mental health condition characterised by psychotic episodes where individuals lose touch with reality, experiencing delusions and hallucinations.

Dr Niall Campbell, a consultant psychiatrist at the Priory rehabilitation centre, warns of a deepening public health issue, stemming from easy online access to highly potent forms of the drug known as ‘skunk’. 

Made from unpollinated cannabis plants which naturally contain higher levels of THC – the main psychoactive ingredient – skunk greatly increases the risk of paranoia and hallucinations.

‘There has been a visible rise in the number of people needing intensive support for psychosis as a result of cannabis use,’ said Dr Campbell. 

‘I don’t think this is surprising given how easy skunk is to buy. What begins with smoking a few ‘joints’ and feeling a bit paranoid can easily escalate. 

Over time people can reach a psychotic state which won’t go away, even if they stop smoking – they can become very depressed or suicidal.’

It comes after the London Drugs Commission released a report earlier this year calling for more services to tackle cannabis addiction.