[6][7] Side effects of the combination of an estrogen and norelgestromin include menstrual irregularities, headaches, nausea, abdominal pain, breast tenderness, mood changes, and others.

[6][4][7] These patches mediate their contraceptive effects by suppressing gonadotropin levels as well as by causing changes in the cervical mucus and endometrium that diminish the likelihood of pregnancy.

[4] Side effects associated with the combination of ethinylestradiol and norelgestromin as a transdermal patch in premenopausal women, with greater than or equal to 2.5% incidence over 6 to 13 menstrual cycles, include breast symptoms (including discomfort, engorgement, and/or pain; 22.4%), headaches (21.0%), application site reactions (17.1%), nausea (16.6%), abdominal pain (8.1%), dysmenorrhea (7.8%), vaginal bleeding and menstrual disorders (6.4%), mood, affect, and anxiety disorders (6.3%), vomiting (5.1%), diarrhea (4.2%), vaginal yeast infections (3.9%), dizziness (3.3%), acne (2.9%), migraine (2.7%), weight gain (2.7%), fatigue (2.6%), and pruritus (2.5%).

[4][3] Nonetheless, transdermally-administered norelgestromin does not counteract the increase in sex hormone-binding globulin levels produced by ethinyl estradiol.

[1][2][3] The metabolism of norelgestromin takes place in the liver and is via transformation into levonorgestrel (conversion of the C3 oxime into a ketone) as well as hydroxylation and conjugation.

[4] However, because norelgestromin is used parenterally, first-pass metabolism in the liver and gastrointestinal tract that normally occurs with oral administration are avoided.

[17] Norelgestromin is more specifically a derivative of norethisterone (17α-ethynyl-19-nortestosterone) and is a member of the gonane (18-methylestrane) subgroup of the 19-nortestosterone family of progestins.

[5] It is not listed as being marketed in Australia, New Zealand, Japan, South Korea, China, India, or certain other countries.