Nurse Gail Ingram explains the statistics used to determine morning after pill odds:
My girlfriend had a hot weekend sexcapade that required emergency contraception. I was getting all the juicy details when she said, “I know I shouldn’t take the morning after pill too many times because it eventually stops working the more times I take it.” She said she hopes it works this time but asked me when her luck will run out.
First of all, the morning after pill (which is levonorgestrel marketed as Plan B, Next Choice, and Levonorgestrel Tablets) does not randomly stop working and there is no such thing as building up resistance. It doesn’t help that the Levonorgestrel Tablets package insert says the “failure rate” accumulates over time with repeated use. This is confusing because it sounds like the drug will accumulate over time but the statement is actually referring to generalized averages.
If the morning after pill is taken within 24 hours of sloppy sex, it is 95% effective in preventing pregnancy. According to the FDA-approved label for Plan B, it is 89% effective when taken as far out as 72 hours. However the World Health Organization did its own study and found slightly different results. They tested levonorgestrel (the generic version of Plan B) and found it is 85% effective when taken between 25 and 48 hours and only 58% effective when taken between 49 and 72 hours. Both data sets report 95% effectiveness when taken as soon as possible. Meaning, the more time that passes after unprotected sex, the less effective the morning after pill becomes.
Wording the statistics differently can make them more confusing. For example, another way to say “85-89% effective” is to use its inverse. This is translated into “1 out of 8 women will become pregnant.” This can lead someone to believe that they are guaranteed to get knocked up if they use the pill 8 times. It just isn’t that simple. Pregnancy depends on many factors including ovulation, stress levels, co-existing health conditions, genetics, and age among other things. Some women metabolize the morning after pill differently and on the guy’s end, some sperm aren’t healthy and they don’t survive long enough to get to their destination.
Every situation is different and every couple is different. You might be a woman who will get pregnant every time she has sex within 5 days of ovulation or you might be a guy with super human swimmers. We just don’t know. But if this is the case, and the two of you found each other, you are probably testing the odds. For the ladies, regular birth control, like the daily pill or an IUD, is more effective and recommended by the makers of emergency contraception.
But on the rare occasion that the morning after pill is needed, here are some other things to know. Every pharmacy has different rules for dispensing emergency contraception because the regulations for dispensing it are constantly changing. No prescription is needed to purchase Plan B, therefore no ID is required to show proof of age. ID is required for Levonorgestrel Tablets and Next Choice. If your ID says you are under 17, you’ll need a prescription. However, the regulations for Next Choice are being revised and some pharmacies are already selling it without carding. Plan B is the most expensive (Rite Aid $49.99, CVS $50, Walgreens $54.99) and Next Choice is less (CVS $39.99, Walgreens $44.99) but both contain the same active ingredient. Whichever brand you buy, for the best results, take the pill before leaving the drug store.
I also told my friend to expect some spotting and that her cycle will be off schedule. If she hasn’t had a visit from Mother Nature (AKA her period) seven days past the expected start date, then she should get a pregnancy test. Intense lower abdominal pain could indicate an emergency (ectopic pregnancy) and requires immediate medical attention. 3 weeks after unprotected sex, she should also look into STI (sexually transmitted infection) testing.