How effective is the birth control patch?

Birth control patch effectiveness

If you use it perfectly, the patch is 99% effective. But people aren’t perfect, and it can be easy to make a mistake — so in reality, the patch is about 93% effective. That means about 7 out of 100 patch users get pregnant each year.

The better you are about changing your patch on time, the better it will work. But there’s a very small chance that you could still get pregnant, even if you always use the patch correctly. In fact, your chances of getting pregnant on the patch depends on how well you follow the directions for using it.

Make sure the patch always sticks tightly to your skin. Don’t reapply a patch that is no longer sticky enough to stay all the way on, and don’t use tape or other materials to stick a non-sticky patch back on your skin. Check your patch every day to make sure all the edges are sticking correctly.

If you often forget or misplace things, you may want to use another method that you don’t have to remember to change every week, like the IUD, implant, or shot. They’re easier to use and better at preventing pregnancy. But if you decide the patch is right for you, make sure you always put your new patch on on time so it works as well as possible. 

What makes the patch less effective?

The main thing that makes the patch not work is not using it correctly. That means you’re more likely to get pregnant if you don’t put on a new patch every week, or if the patch falls off for more than 1 or 2 days, depending on which patch you’re using — 1 day (24 hours) for Twirla, and 2 days (48 hours) for Xulane.

Some medicines or supplements can also make the patch less effective:

• The antibiotics Rifampin, Rifampicin, and Rifamate (other antibiotics don’t make the patch less effective)

• The antifungal Griseofulvin (other antifungals don’t make the patch less effective)

• Certain HIV medicines

• Certain anti-seizure medicines (these are sometimes also used to treat psychiatric disorders like bipolar disorder)

• The herb St. John’s Wort

Use condoms as a backup method if you’re taking any of these medicines while you’re on the patch. Switch to a different type of birth control if you’ll be taking them for a long time.

The patch may not work quite as well to prevent pregnancy if you have a higher weight. Your nurse or doctor can help you decide if there’s any reason the patch won’t work well for you.

Being in water for more than 30 minutes at a time may make it easier for the Twirla patch to fall off. If you’re a swimmer or often spend more than 30 minutes in water, talk with your nurse or doctor about the best method of birth control for you.