Men are being warned to be wary of counterfeit drugs sold online for erectile dysfunction that can contain dangerous chemicals and pose a serious risk to health.
An analysis of pills from 22 different websites claiming to sell drugs such as Viagra and Cialis found 77 per cent of samples were fake and contained only 30 to 50 per cent of the active ingredient advertised on the label.
Many of the counterfeit drugs also contained undeclared substances such as gypsum, found in fertiliser, commercial paint and printer ink, said Urological Society of Australia and New Zealand president Dr Stephen Ruthven.
The study, by San Diego Sexual Medicine's Dr Irwin Goldstein, suggested the fakes could also contain other harmful ingredients including antihypertensive medications.
Ruthven said self-medication of this kind carried very real health risks.
''Many people simply assume they are buying the real product, when in fact most online purchases from international sites are illegal counterfeits."
The study comes after Australia's drug regulator last week warned men not to buy or consume two products claiming to contain 100 per cent herbal ingredients, Ultra Men for Men and Rock Hard for Men.
An investigation by the Therapeutic Goods Administration found the products contained two undeclared prescription substances, tadalafil and glibenclamide.
Tadalafil is the active ingredient in Cialis, a prescription-only erectile dysfunction product, and glibenclamide is used to control blood glucose levels.
The TGA said the tablets had not been assessed for quality, safety and efficacy.
The place of manufacture was also not approved by the regulator.
The TGA warned consumers to be extremely cautious when buying medicines from unknown international internet sites.
Worldwide sales of fake drugs in 2010 was estimated to be about $94 million.
Ruthven said erectile dysfunction drugs such as Viagra and Cialis targeted vulnerable men.
Men often feel embarrassed about discussing the condition with doctors, he said, but it was important to do so to properly diagnose the problem and rule out other health risks, including metabolic problems and heart disease.
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