The birth control patch, or Ortho Evra, is a transdermal (meaning "through the skin") contraceptive method, which supplies the body with hormones that prevent pregnancy. Much like other skin patches, such as the nicotine patch, the birth control patch works by delivering medicine to the body directly through the skin.

Using the Patch

A small adhesive patch is worn on the skin for three weeks out of each month. A new patch is applied at the start of each week. No patch is used during the fourth week of the month. The patch is worn on the torso (excluding breasts), buttocks, abdomen, or upper arm.

How it Works

The patch works by delivering a combination of hormones--synthetic estrogen and progestin--into the body. As with other hormonal contraceptives, the patch works by preventing ovulation. It also causes changes in cervical mucus, which can block the passage of sperm.

Effectiveness

Similar to other hormonal contraceptive methods (like the pill and NuvaRing), the patch is considered about 99 percent effective against pregnancy when used correctly. The patch does not prevent the transmission of sexually transmitted infections.

Side Effects and Contraindications

Possible side effects from the patch include headaches, nausea, breast symptoms, spotting or irregular vaginal bleeding, skin irritation at the site where the patch is applied, problems with contact lenses, fluid retention, increased blood pressure, melasma (skin darkening/blotches), weight gain, vomiting, diarrhea, muscle spasms, tiredness, changes in menstruation (painful, heavier, or more frequent periods), cramps, vaginal discharge, and mood problems. The birth control patch should not be used with certain medications, as they may decrease its effectiveness. Some medications can also be dangerous if taken while using the patch. A physician should always be consulted when combining the patch with any prescription, over the counter medication, or supplement. People with certain health conditions and women who are breastfeeding should not use the patch. The patch may also be less effective in women who weigh more than 198 lbs.

Estrogen and Possible Safety Concerns

Because the patch delivers hormones directly through the skin (as opposed to oral contraceptive pills, where some of the medicine is first processed by the stomach), the patch exposes the user to much higher estrogen levels than an oral contraceptive pill. A person using the patch is exposed to about 60 percent more estrogen than an average pill user, and the patch may cause more or more severe side effects than the pill. The birth control patch may also carry a higher risk of venous thromboembolism, or blood clots in the legs or lungs, than other hormonal birth control methods. Because of this risk, the patch carries an FDA warning.

Source:

Ortho Evra Website

FDA Warning

The Birth Control Patch on Wikipedia