Associate Clinical Professor, St. John's University College of Pharmacy and Health Sciences
314 Answers 8,790 Helpful Votes 25 Followers
Errin is a progestin-only form of birth control, commonly referred to as the "mini-pill" because it does not contain any estrogen. If you start the pack of pills on the first day of your menstrual cycle, you can expect them to be effective after 48 hours.
In the mean time, you should use a back-up method of contraception such as a condom for the first two days you are taking the pill. Also, if you forget to take a pill, or are more than three hours late in taking it, you should use a back-up method of contraception for 48 hours.
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