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Warning as high potency synthetic opioids identified in illicit benzodiazepine market

Published: 11 December 2023

Welsh public health experts in the UK’s only national drug testing service are warning that people may not be getting what they think they are getting when buying benzodiazepines.

They are particularly concerned about an influx of highly potent synthetic opioids being identified within substances sold as benzodiazepines.

Benzodiazepines are medicines available by prescription.  However, some people may be buying them in uncontrolled markets, often online, for common conditions like anxiety or sleeping problems.

Since September 2023, WEDINOS, the drug testing service operated by Public Health Wales, has received over 20 samples of benzodiazepines containing nitazenes, a highly potent synthetic opioid.  These samples included substances purchased online by members of the public from across the UK, likely believing them to be genuine pharmaceutical products.

Nitazenes are a highly potent synthetic opioids that are increasingly being identified within the UK illicit drug supply. Although nitazenes are typically detected within other opiates, WEDINOS has identified their presence in a growing number of samples submitted as other drugs, particularly diazepam, a benzodiazepine medicine that treats anxiety, muscle spasms and seizures or fits. 

Diazepam is also sometimes used non-medically. The substances have predominantly been submitted to WEDINOS as tablets, but have also been submitted in other forms. 

The service has also detected nitazenes in samples submitted as other drugs including alprazolam or oxycodone.

Overdoses from opioids like nitazenes can be reversed if Naloxone, a life-saving medicine, is administered. Within Wales, Naloxone can be ordered free of charge online from Dan 24/7, the Welsh drug and alcohol helpline.
Prof Rick Lines, Head of Substance Misuse at Public Health Wales and WEDINOS said:

“We’re concerned that people taking these substances could quickly find themselves in a life-threatening situation. For individuals experiencing negative effects from taking what they believe are benzodiazepines, they may in fact be experiencing a more serious opioid overdose that should be treated with Naloxone.

“We want to raise awareness of the dangers and make sure that people know that Naloxone is a lifesaving medicine available free of charge in Wales to reverse the effects of an opioid overdose.  Anyone who believes they are experiencing an opiate overdose should contact 999.

“People can further protect themselves by ensuring that they only obtain prescription medicines via their GP.”

Luke Ogden from Dan 24/7 said:

“We are concerned that people may not be getting what they think they are getting when they buy illicit drugs.

“We offer an easy online ordering service for Naloxone, meaning that people can get their own Naloxone kit to carry and use in the event of a suspected opioid overdose.”

Access to advice and Naloxone kits is available at or by calling Dan 24/7 on 0808 808 2234.