A contraceptive patch, also known as "the patch", is a transdermal patch applied to the skin that releases synthetic oestrogen and progestogen hormones to prevent pregnancy. They have been shown to be as effective as the combined oral contraceptive pill with perfect use, and the patch may be more effective in typical use. Xulane and Twirla are approved for use in the United States. Evra is approved for use in Canada and marketed by Janssen Inc., and it is approved for use in the United Kingdom and in Europe and marketed by Janssen-Cilag. The patches are packaged in boxes of three and are only available by prescription. Medical uses Because the patch works similar to that of birth control pills, many of the benefits are the same. For example, the patch may make a woman's period lighter and more regular. It may also help to clear acne, decrease cramps, and reduce PMS symptoms. Additionally, the patch is associated with an increased protection against iron deficiency anemia, ovarian cysts, pelvic inflammatory disease, and endometrial and ovarian cancer. The patch is a simple and convenient form of birth control that requires weekly attention. When a woman stops using the patch, her ability to become pregnant returns quickly. Side effects In three large clinical trials involving a total of 3,330 women using the Ortho Evra / Evra patch for up to one year, 12% of users discontinued the patch because of adverse events. The most frequent adverse events leading to patch discontinuation were: nausea and/or vomiting (2.4%), application site reaction (1.9%), breast discomfort, engorgement or pain (1.9%), headache (1.1%), and emotional lability (1.0%). The most frequent adverse events reported while using the Ortho Evra / Evra patch were: breast discomfort, engorgement or pain (22%), headache (21%), application site reaction (17%), nausea (17%), upper respiratory tract infection (10%), menstrual cramps (10%), and abdominal pain (9%). Breakthrough bleeding and/or spotting while using the Ortho Evra / Evra patch was reported by: 18% in cycle 1, 12% in cycle 3, 8% in cycle 6 and cycle 13. Breakthrough bleeding (requiring more than one pad or tampon per day) was reported by: 4% in cycle 1, 3% in cycle 3 and cycle 6, and 1% in cycle 13. Overall, side effects that tend to go away after two or three months include bleeding between periods, breast tenderness, and nausea and vomiting. Symptoms that may last longer include