More than one in three illicit drug samples contain unexpected substances, testing finds

Between April 2025 and March 2026, 36.6% of drug samples submitted to the Welsh Emerging Drug Identification Service did not contain the substance expected by the buyer. The illicit drug market frequently involves substitution, where buyers cannot rely on the drug's appearance, packaging, or name to determine its contents. A concerning trend identified in the latest Wedinos report is the emergence of synthetic opioids known as orphine analogs, which are highly potent and can produce powerful effects at very small doses.

These analogs were discovered alongside veterinary sedatives in samples labeled as heroin, making it difficult to predict the risks and effects for unsuspecting users. The problem extends beyond Wales, with orphines implicated in at least 22 deaths in the UK and seven of these substances added to the list of class A drugs under the Misuse of Drugs Act 1971.

The illicit drug market's substitution issue is not limited to heroin; it also affects cannabinoid products. A significant portion of THC, CBD, or cannabinoid vape samples tested contained synthetic cannabinoids, or spice, instead of the expected substance. These lab-created compounds can produce much stronger and unpredictable effects, including severe anxiety, panic, hallucinations, psychosis, and seizures.

Drug-checking services like Wedinos provide valuable harm reduction information by analyzing individual samples and identifying contained substances. However, drug testing has limitations, as it cannot guarantee that future products from the same seller or batch will contain the same substances. Despite these limitations, drug-checking services offer crucial support in navigating the increasingly complex and unpredictable illicit drug market.