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"Can cold temperatures lessen the effectiveness of birth control?"

ZocdocAnswersCan cold temperatures lessen the effectiveness of birth control?


I walked back from the pharmacy with my new pill pack in my backpack. It was probably around 30 degrees, and I was outside for 20 minutes or so. Are my pills still good?


The short answer to your question is yes, your birth control pills are still good. Cold does not affect the effectiveness of birth control pills. However, there are a few other things you should know about the effectiveness of birth control pills going forward, so it is important to speak with your primary care physician. First, you should never take birth control pills that have expired. Expired pills do have less effective hormones and are likely not to prevent pregnancy in the way that you want. The second most important factor in the effectiveness of birth control pills is whether or not you miss one. If you miss one pill, the effectiveness drops from greater than 90% to somewhere around 70%. The effectiveness drops more if you miss more than one pill. Finally, there are other medications that can affect the effectiveness of birth control. There are certain antibiotics for example which can interact with the pill and increase the metabolism of the hormones rendering them ineffective. I should say that most antibiotics do not do this despite the fact that it is widely thought by the public that any antibiotics will render them ineffective. I suggest that you schedule an appointment with your primary care physician so that you can become more educated on how to take your birth control and how to make sure that it remains effective.

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