page_title: Contraceptive patch
section_title: Mechanism of action
hierarchical_section_title: Contraceptive patch / Mechanism of action
caption_attribution_description: English: Birth Control Patch See a full animation of this medical topic.
context_page_description: 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.
context_section_description: Like all combined hormonal contraceptives, Ortho Evra / Evra works primarily by preventing ovulation. A secondary mechanism of action is inhibition of sperm penetration by changes in the cervical mucus. Hormonal contraceptives also have effects on the endometrium that theoretically could affect implantation; however, no scientific evidence indicates that prevention of implantation actually results from their use.
  The 20 cm² Ortho Evra contraceptive patch contains 750 µg ethinylestradiol (an estrogen) and 6000 µg norelgestromin (a progestin).
  The 20 cm² Evra contraceptive patch contains 600 µg ethinylestradiol and 6000 µg norelgestromin.
  The Ortho Evra contraceptive patch and the Evra contraceptive patch are both intended to gradually release into the systemic circulation approximately 20 µg/day of ethinylestradiol and 150 µg/day of norelgestromin.
caption: Illustration depicting transdermal contraceptive patch.
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