Emergency contraceptive pill(s) needs to be taken within 72 hours of unprotected sexual intercourse (UPSI), with lower efficacy up to 120 hrs after UPSI.
For women who weigh > 70 kg or over 26kg/m2 and those who have taken enzyme inducing medication drugs in the past 4 weeks then two pills (2 x 1.5 mg tablets) are recommended.1
The estimated pregnancy rate at the daily equivalent of 1.5mg increased significantly from 1.4% among the group of women weighing 65–75 kg to 6.4% and 5.7% in the 75–85 kg and > 85 kg groups respectively (based on 2 RCTs).2
A barrier method of contraception needs to be used until the next period. A more effective option is to insert a copper IUD (99% effective) which can be inserted up to 5 days post-intercourse and has the advantage of providing longer term contraception. Vomiting within 3 hours also necessitates another treatment.
This Gem has been checked by Dr Karen Hoare, Nurse Practitioner.