Three people have been found guilty of conspiracy to supply millions of pounds worth of counterfeit Viagra and drugs used to treat male hair loss.
A fourth man also admitted to Kingston Crown Court his involvement in the scam and has been sentenced to four-and-a-half years in prison.
Investigators say the convictions are the result of the biggest counterfeit drugs bust in British history.
The fake medicines were made in factories in India, China and Pakistan.
A chance interception by UK customs officers of a parcel containing 12,000 fake Viagra tablets addressed to 58-year-old gang member Gary Haywood led to a huge investigation spanning three continents.
Large quantities of the counterfeit drugs were shipped into the UK from factories abroad, before being repackaged and sold over the internet to customers in Britain, the US, Canada and the Bahamas.
The trial at Kingston Crown Court heard the products, which contained around 90% of the normal active ingredient found in authentic tablets, were placed in forged packaging with fake logos and patient information leaflets.
The scale of the counterfeiting was exposed when Haywood, from Leicester, who claimed to be working for drugs firm Pfizer, told undercover investigators on camera that "within 6-8 weeks I will be able to supply up to a million tablets".
The Medicine and Healthcare products Regulatory Agency (MHRA) went on to search Haywood's Leicestershire home and found more than £1.5m of counterfeit drugs.
The MHRA said the conspiracy involved fake versions of Pfizer's Viagra, prescribed to treat men suffering from impotence or erectile dysfunction, Eli Lilly's competitor product Cialis and Merck & Co's Propecia, used to treat male baldness.
BBC correspondent Jon Brain said the gang relied on customer embarrassment about buying so-called "lifestyle medicines" to prevent them from complaining to the authorities.
Sarah Jarvis from the Royal College of General Practitioners warned against taking such counterfeit drugs.
She told BBC News 24: "It is highly likely that the people who buy these drugs online would not dream of going out into the back streets of India and eating off the floor their lunch from a street cafe, and yet that's effectively what they're doing."
Haywood, along with Ashwin Patel, 24, of north London, and Zahid Mirza, 45, of Ilford, Essex, were found guilty last month of a number of counts of conspiring to sell fake medicines.
The verdicts could only be reported on Monday after reporting restrictions were lifted by the court.
The three men are due to be sentenced next month.
Ashish Halai, 31, of Borehamwood, Herts, described as the UK "lynchpin" of the operation, had already pleaded guilty to four counts of conspiring to sell the fake drugs before the trial started almost nine months ago.
He was jailed for four-and-a-half years.
Sentencing, Judge Nicholas Price said: "Greed is the over-riding motivation for such an offence."
He added that it was "an undeniably lucrative business" where consumers were "easy prey, often too embarrassed to seek help from their doctors".
Mick Deats, head of enforcement at the MHRA, advised people to avoid buying medicines online where the risk of being supplied a counterfeit product was "substantially increased".
He added: "This successful prosecution should serve as a clear signal to those who counterfeit and supply these drugs."
The jury failed to reach verdicts on four other defendants.
George Patino, a doctor from Mexico, Alpesh Patel, a pharmaceutical sales representative from Kingsbury, London, pharmacist Rajendra Shah of St Albans, Herts, and businessman Ketan Mehta of Grove Park, London, will face a retrial next year.