Update on Emergency Contraception – Safety

(Published March 2011)

Millions of women have used emergency contraception (EC) safely and effectively. The benefits of using emergency contraception pills (ECPs) outweigh the risks in all situations.¹ ECPs can be safely used by women who have contraindications to routine use of combined hormonal contraception. Women with previous ectopic pregnancy, cardiovascular disease, migraines, and liver disease may use ECPs. In fact, research has shown that pregnancy poses a greater threat to women with medical problems such as thromboembolic and liver disease than a 1-day dose of estrogen and/or progestin.²

Women who are breastfeeding may safely use progestin-only ECPs, although they may experience a transient change in their milk supply. Use of ulipristal acetate (UPA) EC is not recommended for breastfeeding women.

No risk of serious harm for moderate repeat use of progestin-only ECPs appears to exist.³ UPA EC is not recommended for repeated use within the same menstrual cycle, as safety and efficacy have not been evaluated. The risk of birth defects does not increase if pregnancies occur after use of progestin-only ECPs.  The evidence to date suggests that UPA EC does not cause birth defects, but the data is extremely limited. Postmarketing surveillance of since 1999 has shown no reports of overdose, overuse, or abuse.⁴ Levonorgestrel ECPs do not increase the risk of ectopic pregnancy.⁵ A history of ectopic pregnancy is not a contraindication for use of UPA EC.

Possible ECP adverse effects include nausea and vomiting, abdominal pain, breast tenderness, headache, dizziness, and fatigue. These effects usually do not occur for more than a few days after treatment, and they generally resolve within 24 hours.³ Considerably fewer adverse effects occur with progestin-only ECPs compared with combination products. Combination ECPs can cause nausea in up to 50% of women and vomiting in up to 20%.^6,7 Women may experience a shorter or longer menstrual cycle depending on when ECPs are taken.^8,9

References:

1. World Health Organization. Medical eligibility criteria for contraceptive use. 3rd ed. Geneva: World Health Organization; 2004.
2. Prine L. Emergency contraception, myths and facts. Obstet Gynecol Clin North Am. 2007;34:127–36, ix–x.
3. Trussell J, Raymond EG. Emergency contraception: a last chance to prevent unintended pregnancy. Accessed at http://ec.princeton.edu/questions/ec-review.pdf, June 24, 2010.
4. Scolaro KL. OTC product: Plan B emergency contraception. J Am Pharm Assoc. 2007;47:e2–3.
5. Cleland K, Raymond E, Trussell J, et al. Ectopic pregnancy and emergency contraception: a systematic review. Obstet Gynecol. 2010;115:1263-6.
6. Task Force on Postovulatory Methods of Fertility Regulation. Randomised controlled trial of levonorgestrel versus the Yuzpe regimen of combined oral contraceptives for emergency contraception. Lancet. 1998;352:428–33.
7. Trussell J, Ellertson C, Stewart F. The effectiveness of the Yuzpe regimen of emergency contraception. Fam Plann Perspect. 1996;28:58–64, 87.
8. Gainer E, Kenfack B, Mboudou E, et al. Menstrual bleeding patterns following levonorgestrel emergency contraception. Contraception. 2006;74:118–24.
9. Tirelli A, Cagnacci A, Volpe A. Levonorgestrel administration in emergency contraception: bleeding pattern and pituitary-ovarian function. Contraception. 2008;77:328–32.