Thousands of illegal medicine have been seized in a series of raids on Eastern European supermarkets.
The raids took place on shops in Boston, Lincolnshire and had been prompted by a recent death in the town.
Rinald Fisers, aged 41 and a Latvian national, had bought an unlicensed drug from a shop for a stomach ulcer.
The national agency behind the raids said the drugs were freely available in parts of Europe but are illegal in the UK without a prescription.
Thousands of pounds worth of drugs were seized which included painkillers and several pharmacy only drugs, such as No-Spa which treats stomach cramps.
'Can't guarantee safety'
Danny Lee-Frost, from the Medicine and Healthcare Products Regulatory Agency, said they had been alerted to the problem of prescribed drugs being sold over the counter in Boston after a coroner raised concerns following Mr Fiser's death.
It had been the second death of its kind in 12 months.
Mr Lee-Frost said: "If they [the drugs] are not licensed in the UK then we can't guarantee the safety and quality.
"Also we don't know what the audit trail of the products are - where they come from, who's been looking after them, what kind of flight conditions they have been in.
"They have been totally out of that regime."
An agency spokesman said evidence showed many migrant workers across the country were not accessing healthcare services and instead relying on their local stores that sold medicines.
He added that the raids were part of raising awareness among Eastern European communities and educating them on the dangers of taking prescription only drugs without seeking medical advice.
The shops raided on Thursday will be visited again to ensure they are not still selling unlicensed medicines.