Four identical recreational pills found on sale in the UK contain drastically different chemicals and could leave users with unexpected side effects, experts have warned.
The colourful pharaoh pills are all approximately 1cm in length and width, the same shape and have the same pattern pressed into them.
They are reportedly sold as MDMA.
The brown pills contain what was expected - MDMA, but the blue ones contain 4-CMCm, a cathinone with more stimulation and less euphoria than MDMA.
The pink pills contain eutylone, a potent cathinone that causes severe insomnia and psychosis, and the yellow ones contain benzocaine, a local anaesthetic used in dentistry and as a bulking agent for cocaine, which is not psychoactive.
They were part of a set of drugs tested from the Parklife Festival in Manchester by not-for-profit drugs company, The Loop.
Professor Fiona Measham, chair of criminology at Liverpool University and the director of The Loop, told the BBC the different ingredients in the same pills signal a huge safety problem.
She said: "People might buy a pill and have no idea what is in it and have very different experiences.
"They might try to buy more of a pill after an okay experience and then what they get might have totally different contents."
She added that people need to know how pills have changed.
"If people can test they should and always have a tiny, tiny dose and wait a couple of hours to see the effect before having more."
But added her best safety advice was "not to take the drugs".
Prof Measham added that a shortage of MDMA may be driving a massive shift in the UK drug market.
She added: "It's difficult to overstate how much the drug market has changed since lockdown, Covid and Brexit.
"Partly because of Brexit there is a lack of road haulage and lorry drivers and this has meant for example shortages to milkshakes for McDonalds, and we wouldn't be surprised to see similar disruptions to illegal supply chains."
