The Ortho-Evra birth control patch exposes women to dangerous levels of estrogen -- posing a possible two-fold increased risk of blood clots -- and should be removed from the market within six months, says a Public Citizen petition filed Thursday with the U.S. Food and Drug Administration.

Compared to women who use standard oral contraceptives, those who use the Ortho-Evra patch experience increased side effects such as breast discomfort, severe menstrual pain, nausea and vomiting, and are more likely to stop using a contraceptive. In addition, the patch doesn't improve birth control, according to evidence compiled by Public Citizen.

Since immediate removal of the Ortho-Evra patch from the market carries the risk that some users may not immediately replace the patch with another form of birth control, Public Citizen suggested a six-month phase-out period. During that time, the patch would be available for refill prescriptions to allow women time to meet with their health-care provider to discuss other forms of birth control.

"Women deserve a level of risk at least comparable to or less than the pill for their hormonal contraceptive. The absence of any evidence of a unique benefit combined with the considerable safety problems of high-dose, variable estrogen exposure in Ortho-Evra tips the balance of risks and benefits against its availability as a contraceptive." Dr. Sidney Wolfe, director of the Health Research Group at Public Citizen, said in a prepared statement.

The Ortho-Evra patch received FDA approval in 2001.

A spokeswoman for the maker of the patch -- Ortho Women's Health & Urology, a J&J company -- said, "Ortho-Evra is a safe and effective hormonal birth control option when used according to its labeling," the Associated Press reported.

"Hormonal birth control methods have benefits and risks," said Gloria Vanderham. "The approved labeling has always stated the known risks associated with its use."