Counterfeits of the erectile dysfunction drug Cialis have been seized in the Toronto area, prompting Health Canada to issue a warning that bootleg drugs can pose serious health risks.

Health Canada's advisory on Wednesday reminds people that unauthorized and counterfeit health products have not been reviewed by the department for safety, quality or effectiveness.

All Cialis blister packs authorized for sale in Canada have a coloured oval on the front of the pack that changes colour from copper to green when the package is raised up and down. Health Canada

The seized counterfeit Cialis actually contains sildenafil, which may pose serious health risks, particularly for people with heart problems.

Cialis that is authorized for sale in Canada contains a different prescription medication called tadalafil.

"In order to minimize health risks, Canadians should not take any prescription drug that has not been prescribed to them by a health-care practitioner," Health Canada advised.

Consumers can identify counterfeit Cialis by examining the packaging of the blister packs, the department said.

All Cialis blister packs authorized for sale in Canada have a coloured oval on the front of the pack that changes colour from copper to green when the package is raised up and down in front of you — a feature that is not found in counterfeit packs.

The counterfeit packs also have a lot number of 05668 and have the active ingredient listed as "Tadalafil" in four different languages, Health Canada said.

Products that have been assessed by Health Canada include an eight-digit Drug Identification Number (DIN), a Homeopathic Medicine Number (DIN-HM) or a Natural Product Number (NPN) on the label.

The department said it has been working with the RCMP and has contacted Eli Lilly, the manufacturer of authorized Cialis.

One of the counterfeit blister packs of Cialis. Health Canada