At the Interpol conference on pharmaceutical crime in Dublin this week the global crime agency says the growth in crime involving fake or tampered-with medicines "threatens the lives of millions of people" and undermines health systems worldwide.
"We are talking about hundreds of tonnes of medicines and millions and millions of pills that are counterfeit, that are floating over the markets through illicit and licit channels," Aline Plancon, head of Interpol's pharmaceutical crime unit, tells AFP.
The agency looked particularly at dieting drugs, with the conference hearing that Irish women are playing 'Russian Roulette' with their health by purchasing illegal slimming pills on the Internet - risking heart attacks, strokes and mental breakdown.
And fake versions of erectile dysfunction drug Viagra (sildenafil) - manufactured by Pfizer and currently one of the biggest victims of counterfeiters - is being sold online in the form of tablets made of chalk.
Birth control pills manufactured from rice flour are some of the other counterfeit medications are also being bought online, the conference heard.
Rogue ingredients such as brick dust, cement, floor polish, cartridge ink, talcum powder, leaded paint, and even a form of rat poison - strychnine - have all been discovered in certain products.
Interpol says that criminals are increasingly involved in the trafficking of fake medicines.
The agency's focus is predominately on black-market medicines but investigations are on-going into cases where legitimate medicines were suspected to have been stolen by the Italian Mafia - with links to organised crime syndicates in Romania and Cyprus - before re-emerging in other EU countries.
A number of drugs were alleged to have been stolen in Italy and were later discovered in the UK, Germany and Finland, sparking an alert by the European Medicines Agency (EMA) in April.
In May this year reports also linked the Camorra organised crime syndicate to the theft of Roche's breast cancer drug Herceptin (trastuzumab), and its subsequent falsification and introduction into European supply chains.
It later emerged that some of the Herceptin vials were diluted and others had their contents swapped for antibiotics.
Plancon says: "You can see the Mafia people saw the opportunity to make money and they know that pharmaceutical crime is one of the good havens for them right now because of lack of legislation and the complexities of co-ordination in countries."
Interpol's largest operation targeting fake medicines in 111 countries led to the seizure last May of more than 9.6m illicit tablets worth $32m (€25.4m), the closure of 12,000 web sites and 434 arrests.