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Emergency Contraception – what’s your plan B?

emergency contraception

Here’s a patient: female, heterosexual, sexually active, no single partner. Uses condoms to prevent pregnancy and STIs (link to post). Regularly tested for STIs. Then she starts seeing one partner more and more often. That turns into monogamy. That turns into “I don’t have any STIs, do you?”. That turns into no condom use. There was no planning ahead, no use of contraception. She looks to emergency contraception the day after.

That story repeats itself in various ways and I’ve heard a lot of them  – condom broke, forgot pills on a vacation, withdrawal didn’t withdrawal in time, simply forgot in the heat of the moment. It’s also routinely used when females seek care after forced intercourse (in addition to other prophylactic measures and counseling). This is what emergency contraception (EC) is for!

Let’s go through Emergency Contraception options … there are more than you think!

basic emergency contraception

First, some basics for all Emergency Contraception:

  • No age restrictions – can be used for females of all ages
  • NOT the same thing as an abortion. These methods do NOT interrupt an ongoing pregnancy. They don’t seem to stop implantation of a fertilized egg
  • They work by delaying ovulation or stopping fertilization of an ovulated egg
  • Not intended to be used regularly due to side effects and efficacy and cost – ie they should not be your go-to method to prevent pregnancy. They should be used as back up method only
  • Time sensitive (see each method for timing after unprotected sex)
  • Although most of the methods are effective if started 3-5 days (72 to 120 hours) after unprotected sex, the quicker the use, the more effective they are. The “morning after” is much more effective than “3 days after”.
specifics emergency contraception

Second, specific Emergency Contraception and what you need to know about each

emergency contraception

Plan B (generic: levonorgestrel)

  • TIMING: 3-5 days after unprotected sex (it’s FDA approved for 72 hours, but even up to 120 hours may help a bit).
  • PROS: one-time dose. Don’t need a prescription– can get directly from pharmacist
  • CONS: Sometimes pharmacist are not properly educated about EC or place judgement on people trying to obtain it – this can make it harder to get in an emergency. Some pharmacies don’t supply it. Body weight affects efficacy. The higher the BMI, the less effective it is. In some studies, it didn’t work at all for females with BMI 30+.

ella, ellaOne, Fibristal (generic name: ulipristal)

  • HOW IT WORKS: prevents ovulation both before and after the LH surge occurs, so time frame where it is effective is longer.
  • TIMING: up to 5 days (120 hours) after unprotected sex
  • PROS: one-time dose. Don’t need a prescription in most states – can get directly from pharmacist
  • CONS: Same as above – pharmacies don’t always have it and pharmacist aren’t always educated about its use. And just like Plan B, body weight affects efficacy. The higher the BMI, the less effective it is. It is probably better overall than Plan B for higher BMI patients though


  • HOW IT WORKS: Prevents ovulations. Stops progesterone (progesterone supports a pregnancy). Thins lining of uterus.
  • TIMING: unclear data, but likely within 3-5 days after unprotected sex
  • PROS: another option is always a pro!
  • CONS: not available in the US. Is one of 2 medications in the “abortion pill” except at a much lower dose (about 1/10 of the abortion pill dose). Still – that’s probably why it’s hard to approve in the US for EC.

Yuzpe Method (high dose birth control pills)

  • HOW IT WORKS: use normal birth control pills, take a bunch of them, 12 hours apart. Depending on the dose of the pills, it will likely be about 4-5 pills at a time, repeated in 12 hours. Taking these pills likely stops ovulation
  • TIMING: unclear but probably up to 72 hours
  • PROS: may be easier to get than the pills above. Some may have a few leftovers from previous prescriptions. People may feel less embarrassed about asking for birth control pills compared to “morning after pill”.
  • CONS: normal to have nausea and even vomiting due to the high doses
emergency contraception


Can use either Copper IUD or one of the hormonal IUDS! They all can work!

  • HOW IT WORKS: unclear how it works as EC. For Copper IUD, experts theorize that copper particles disrupt normal functioning of fallopian tubes and uterus. For hormonal, the progestin may make the fallopian tubes and uterus not optimal for pregnancy. May also interfere with implantation
  • TIMING: within 5 days of unprotected intercourse
  • PROS: provides ongoing contraception afterwards; can be used in females of all weight (same effectiveness, regardless of BMI – unlike the pills above)
  • CONS: need office appointment for insertion – this can be hard to find on short notice. Insertion can be uncomfortable (link Instagram)

Few final tidbits:  

  • If taking pills, if thrown up within 1 hour, the dose probably needs to be repeated. Good new is if the pills caused such a reaction to make someone throw up, it’s likely the hormone level was high
  • Irregular bleeding and spotting or a delay in getting a period is normal after the pills. But don’t forget to take a pregnancy test if a period is late – EC is NOT 100% effective!


May 10, 2021

Original post published: 

* Content reviewed annually for accuracy 

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