There is no single mechanism of action of emergency contraception (EC) (26) as it depends on the time in the menstrual cycle the medication is taken and what method is chosen.  Options for emergency contraception range from high dose combined oral contraceptive pills (the Yuzpe Method), single or multi-dose progesterone methods (levonorgesterol or ulipristral) or placement of a copper IUD.  Specific regimens can be found here (27)  and are most effective 0-72 hours after intercourse with moderate effectivity up to 5 days. (26)  According to the US MEC, given the associated complications and commodities of pregnancy and the short term use of the EC method, there are absolutely no instances in which the risks outweigh the benefits of use. 

Therefore, we should always consider and discuss this option with our adolescent oncology patients. Given the urgency of timing for effective treatment following unprotected intercourse, it is imperative to begin this conversation before the need arising, such as during our general sexual health discussions.  Several barriers to the use of EC have been noted in adolescents including education and understanding of the medicines and cost barriers.  Further barriers relate to the difficulties in accessing medications from the pharmacies, where staff may not approve of or understand the laws regarding EC use in younger patients. (28)  It is also important to understand the exact prescribing laws for EC and adolescents as they apply in your state (Guttmacher).