The danger of buying drugs over the internet was highlighted after a Canadian woman died when she took pills laced with radioactive materials.
Marcia Bergeron, 57, died after taking anti-anxiety medication and sedatives bought online. The drugs were found to contain dangerous amounts of uranium, strontium, selenium, aluminium, barium and boron.
Bergeron started complaining of blurred vision shortly after Christmas, and her hair began to fall out. She was found dead in her home a week later.
"This is a tragic reminder that you should always consult a doctor and never purchase pills online or reply to emails that offer miracle cures at knock-down prices," said Graham Cluley, senior technology consultant at Sophos.
"Self-prescription can not only result in you buying medication that you don't need, but more worryingly there's no guarantee that the pills won't be just a cheap concoction of whatever minerals the sellers can get their hands on, designed for the sole purpose of earning money.
"It's madness to buy drugs from an unknown source. Who knows what's in it?"
Investigators found 100 unlabeled pills in Bergeron's home, which came from a website claiming to be a legitimate Canadian supplier.
The Canadian Pharmacists' Association said that up to 50 per cent of the drugs from online pharmacies can be counterfeit or sub-standard.
"We do not know how many other Canadians could be buying counterfeit medications through the internet," said local Liberal MP Dr Carolyn Bennett. " It is time for the government to act to ensure Canadians are protected."