A contraceptive patch is a patch that delivers hormones (estrogen-progestogen association). When first used it is applied to the skin on the first day of the menstrual period. A patch is then positioned each week for 3 consecutive weeks followed by one week without a patch. In practice the patch is always positioned on the same day of the week (for example if you put on your 1st patch on a Monday you can take off the next patches on a Monday). The menstrual bleed develops during the 7 days when you do not have a patch.
This method of contraception only needs to be changed weekly and can be an advantage for women who forget to take their pill regularly. It may however cause side-effects: breast tenderness, and skin reactions at the application site.
If not contraindicated, you will be prescribed your transdermal, hormonal device by a doctor and it will be dispensed to you by a pharmacy. It is not reimbursed by the French National Health Insurance Funds.