CBC News: Disclosure has learned that every day thousands of young Canadian women are taking a potentially dangerous pill and many don't realize it.

The pill is called Diane-35. More than 800,000 prescriptions were written for the drug last year and the majority of Canadian women are taking it for birth control. That's the problem. The drug was approved by Health Canada as a treatment for severe acne.

While Diane-35 does prevent pregnancy, a U.S. study also found it increases the risk of blood clots by up to four times more than standard birth control pills. When Health Canada approved Diane-35 for sale in 1998, it included a rare restriction for doctors. It says the drug should not be prescribed solely for its contraceptive properties.

Yet, an investigation by Disclosure has revealed that thousands of Canadian women are taking the drug solely for birth control, unaware of the restriction and the potential risks.

When Disclosure revealed that information to Health Canada, the department issued an advisory to Canadian doctors reminding them the drug is meant for cases of severe acne, not solely for birth control.

The company that sells the drug is Berlex Canada, based in Montreal. It says its sales representatives are instructed to promote the drug for acne not birth control. But, Health Canada has confirmed to Disclosure the company is currently under investigation for its promotion of the drug.