Loestrin birth control pills are not an effective method of emergency contraception, according to Drugs.com. These pills prevent a fully developed egg from forming but may not affect one that has already formed. The medication contains the hormones ethinyl estradiol and norethindrone and protects against pregnancy when taken as directed.
Each pack of Loestrin contains three weeks' worth of active pills and one week worth of inactive pills, according to WebMD. The inactive pills do not contain hormones; however, they do contain trace amounts of iron. Loestrin can also regulate menstrual periods and minimize the risk of developing ovarian cysts. Side effects of Loestrin include nausea, bloating and weight fluctuations.