Few of us realise that many of the prescription drugs we are supplied with do not come from directly from the manufacturer but will have been bought from the cheapest places within Europe.
Traders buy legitimate stock from cheaply priced countries, such as Greece, and export those medicines to more expensive countries.
The UK is the biggest market for parallel traded drugs.
But critics point out that the selling on and repackaging of these medicines is undermining security and posing a serious risk to patients by allowing counterfeit products to enter the legitimate supply chain.
Earlier this summer it was discovered that three medicines, which had been parallel imported into the UK, were counterfeit. These were the first cases of their kind in this country.
It is also suspected that counterfeiters, who have become increasingly expert at faking drugs, are now specifically targeting the lucrative European market.
The profits that can be made from counterfeiting genuine medical drugs are far higher than those made from illegal drugs - and the risks much lower.
In "Crossing Europe" Melanie Abbott will be shining a light on the continent's parallel trade in medicines and exploring whether there is a genuine link between counterfeit drugs and the parallel drugs trade.
She will be asking if this trade is really threatening the safety of patients.
BBC Radio 4's Crossing Continents was broadcast on Thursday, 6 September 2007 at 1102 BST.
Reporter: Melanie Abbott
Producer: John Murphy