OTTAWA - Health Canada is warning consumers about the potential risks of buying prescription drugs online from certain websites, which are offering medications not authorized for sale in Canada and thought to be counterfeit.

Those websites are: www.northdrugmart.com, www.northdrugstore.com and www.pharmacyrxworld.com.

Health Canada has identified products on these websites that contain references to brand names and resemble drugs that are authorized to be sold in Canada.

"This may lead consumers to believe they are purchasing drugs that have been reviewed for safety, efficacy and quality by Health Canada," the department said in an advisory Wednesday.

"It is important to note that counterfeit drugs may contain no active or unsuitable ingredients, or dangerous additives. To this end, counterfeit drugs may pose a higher risk than other forms of unauthorized drugs."

Prescription products that have been approved for sale in other countries, or generic products purporting to be the equivalent of authorized products, must still be reviewed by Health Canada and receive their own market authorization or product licence before they may be sold in Canada.

Patients taking prescription drugs without being examined and monitored by a health-care practitioner may not receive the appropriate treatment to maintain health, and also may put themselves at risk for drug interactions or harmful side-effects, the department warned.

There is no assurance that all claims made on the Internet are reliable, said Health Canada. Some websites falsely claim to be Canadian pharmacies and dispense foreign drugs that are not authorized for sale in Canada.

The Ontario College of Pharmacists says the three websites named are not associated with a licensed pharmacy in the province.

Consumers concerned about their health after using products purchased at these websites should consult their health-care practitioner.