May not be as effective when taken with certain medicines
May delay return of normal cycles
If used in early breast-feeding, may reduce milk supply
Pills must be taken every day.
Patches may not fully protect you from pregnancy if they are exposed to direct sun or high heat. This can release a high dose of hormone from the patch, which leaves less for the patch to release later in the week.
Patches deliver more estrogen than low-dose birth control pills do. Some research has found that women using the patch are more likely to get dangerous blood clots in the legs and lungs. The risk may be higher if you smoke or have certain health problems. The U.S. Food and Drug Administration (FDA) suggests that you talk to your doctor about your risks before using the patch.