In England, anyone prescribing weight-loss injections must be registered with the Care Quality Commission.
But in Wales, only doctors are required to register with the Welsh equivalent, Healthcare Inspectorate Wales (HIW), meaning other healthcare professionals are not legally required to meet the same standards or be routinely inspected.
Some experts have described this as inadequate regulation, opening up an unsafe black market for such products.
“The people who elect to get these drugs from unlicensed places are playing Russian roulette with their lives,” said Harris.
“They don’t know what they might be injecting into themselves and that terrifies me.”
The Welsh government said weight-loss treatments such as Mounjaro are prescription-only and “should only be obtained and used in accordance with a prescription from a registered and appropriately trained healthcare professional”.
“No one should purchase prescription only medicines other than from reputable suppliers such as registered pharmacies. Medicines obtained from unregulated sources pose a major risk to people’s safety.
“Healthcare professionals prescribing weight-loss treatments must act in accordance with the standards set by the respective professional regulatory bodies,” they added.