Health Canada has seized counterfeit Cialis and Viagra from various stores in Toronto, Pickering, and Brantford, Ontario. The manufacturers of Cialis and Viagra have confirmed that the seized products are counterfeit. These products are in addition to the counterfeit Viagra that Health Canada had previously seized from Queen St. Variety store and Pacific Fresh Food Market . Selling counterfeit drugs in Canada is illegal. Counterfeit drugs are made to look like authentic products, but they are not the same and may pose serious health risks. Health Canada has not assessed them for safety, efficacy, and quality, and they may contain: no drug at all a higher dosage than shown on the label dangerous contaminants and hidden ingredients Like the authentic versions, the seized products are labelled to contain either the prescription drug sildenafil or tadalafil. Sildenafil and tadalafil should be used only under the supervision of a health care professional. They should not be used by individuals taking any kind of nitrate drug (e.g., nitroglycerin) as they can cause potentially life-threatening low blood pressure. Individuals with heart problems are at increased risk of cardiovascular side effects such as heart attack, stroke, chest pain, high blood pressure, and abnormal heartbeat. Other possible side effects include headache, facial flushing, indigestion, dizziness, abnormal vision, and hearing loss. The best way to make sure your prescription drug is authentic is to buy it from a licensed pharmacy, with a prescription from your health care professional. Prescription drugs cannot be sold outside of a licensed pharmacy and should only be taken under the care of a health care professional because they are used to treat specific health conditions and may cause serious side effects.