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Clinical Summary: Emergency contraceptive pills

2013
Publication type: EC Guidelines
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Indication: Emergency Contraceptive Pills (ECPs) are indicated to prevent pregnancy after unprotected or inadequately protected sex.


ECP Regimens:
Three regimens are packaged and labeled specifically for emergency contraception (EC).

  • 1 tablet of levonorgestrel 1.5 mg, or 2 tablets of levonorgestrel 0.75 mg labeled to be taken twice 12 hours apart (but can safely be taken together)
  • 1 tablet of ulipristal acetate 30 mg
  • 1 tablet of mifepristone 10-25 mg (not widely available)

Certain types of ordinary birth control pills can also be used as EC (known as the “Yuzpe regimen”). Take the pills within 5 days after sex, as soon as possible after the sex act.


How ECPs Work:
The primary mechanism is disruption of ovulation. Other mechanisms have been postulated but are not well supported by data. No evidence supports the theory that ECPs interfere with the implantation of a fertilized egg. ECPs do not cause abortion of an existing pregnancy.


ECP Efficacy:
The levonorgestrel regimen reduces pregnancy risk by at least half and possibly by as much as 80-90% for one act of unprotected intercourse. The ulipristal and mifepristone regimens are more effective than the levonorgestrel regimen. Regular oral contraceptives used as EC (the “Yuzpe regimen”) are less effective.


Safety:
ECPs have no known medically serious complications. Side effects may include altered bleeding patterns, nausea, headache, abdominal pain, breast tenderness, dizziness, and fatigue. ECPs do not appear to be harmful if inadvertently taken in pregnancy.


Precautions and Contraindications:
ECPs have no medical contraindications. Do not take ECPs if you are pregnant because they will not work.


Clinical Screening:
You do not need any examinations or laboratory tests before taking ECPs.


Repeated ECP Use:
ECPs can be used as often as needed, but do not need to be taken more than once every 24 hours if multiple acts of unprotected sex occur. Repeat use of ECPs is perfectly safe, but ECPs are not recommended as a regular, routine contraceptive method because they are not the most effective contraceptive method available.


Drug Interactions:
Concurrent use of some drugs may reduce ECP efficacy. However, the ECP regimen is the same whether or not you are using these drugs.


Follow-up after ECP:
No scheduled follow-up is required after ECP use. But if you have not had a menstrual period by 3 weeks after taking ECPs, consider that you may be pregnant.


Starting or Resuming Regular Contraceptives after ECP Use:
ECPs are not designed to provide contraceptive protection at sex acts that occur in the future. Using a regular contraceptive after taking ECPs is CRITICAL to minimizing your pregnancy risk. Begin hormonal methods (oral contraceptives, patch, vaginal ring, injectables, implants, levonorgestrel intrauterine system) either immediately or after your next menstrual period; if you wait, use a barrier method such as condoms in the interim. Copper- bearing IUDs provide highly effective emergency contraception, so you do not need oral ECPs if you start using this type of IUD within 5 days after sex. Do not rely on fertility awareness methods until you have had at least one normal menstrual period.


Resources

  • International Consortium for Emergency Contraception website: www.emergencycontraception.org
  • The Emergency Contraception website, managed by Princeton University and the Association of Reproductive Health Professionals: www.not-2-late.com