Five university students have been taken to hospital after apparently taking a synthetic cannabis-like drug.
Lancaster University has issued a warning about Spice, a former legal high reclassified as a Class B drug in 2009, after the five needed treatment.
In a warning to students, the university tweeted: "Urgent message: Several students have been hospitalised today after taking legal high Spice - please check on friends and call 999 if needed."
Vicky Tyrrell, a spokeswoman for the university, told the Guardian that police called university authorities to tell them that the students had been taken to the Royal Lancaster Hospital.
"We've got five students who have been taken to hospital with a suspicion that they had taken the drug," Ms Tyrell said. "Of the five, we know that two of them are seriously ill."
According to student paper Scan, the university emailed all students to say: "Five students are in hospital, 2 of them critically ill following a suspected overdose of a drug called Spice. It is extremely important if you have taken the drug to call 999 immediately and call for an ambulance. Please also check on anyone you think may have taken it.
“Spice is a cannabis based drug and can be bought over the internet. Packages may be labelled ‘not for human consumption’.”
Spice is a synthetic cannabinoid which contains the same active chemical tetrahydrocannabinol (THC), possibly leading to paranoia or a change in mood.
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At the time Spice was banned as a Class B drug, drug charity Scope said enforcing it would be difficult because "only those samples containing controlled cannabinoids will be illegal; those just containing psychoactive herbs will not. Forensic testing will be the only way to determine the contents of any given sample."
Spice is only one of a number of products that use chemicals that mimic the cannabis effects. Some, like Spice, are illegal but others are so-called "legal highs" and can be more dangerous than the drug.
Speaking last year, Steve Rolles, senior policy analyst at the charity Transform that campaigns for drug law reform, said that having a more dangerous, legal version of the drug meant Britain's drug policy was "the worst of all worlds".
He told The Huffington Post UK: "Synthetic cannabis might be the straw that breaks the camel's back in terms of cannabis reform.
"We currently have an unbelievably stupid situation where people can buy fake cannabis that's more dangerous. It's utterly ridiculous.
"It's absolutely the worst of all worlds."