The department, along with drug maker Janssen-Ortho Inc., issued the statement based on research that showed a U.S. formulation of the company's patch contraceptive may be associated with a higher risk of blood clots than oral birth control pills.
"We're taking the precaution of giving people an additional heads up that there's a risk of blood clots with the product," said Health Canada spokesperson Alastair Sinclair.
Janssen-Ortho's U.S. formulation is sold under the brand name Ortho Evra. The Canadian produce, sold as Evra, contains a lower dose of estrogen. Still, Health Canada said it believes both products carry the same risk of adverse events.
The advisory noted women who are obese are particularly at higher risk of blood clots. It also points out there is a theoretical risk that exposing the patch to heat could lead to increased exposure of estrogen, so it recommends women wearing an Evra patch avoid saunas and whirlpool baths.
Sinclair said there have been 78 adverse events reported by Canadian users of Evra since the patch hit the market at the beginning of 2004. Of those, 14 were cases of blood clots, and one was a heart attack.
The U.S. Food and Drug Administration issued a similar warning about Ortho Evra in late September.
source - Canadian Press