ECPs can cause nausea, vomiting and abdominal cramps. Other side effects include fatigue, headaches, irregular bleeding, fatigue and breast tenderness. These side effects usually subside within 48-72 hours of taking the drug. However, it’s important to seek medical attention if any of these symptoms persist beyond 48 hours. Additionally, there is a risk of ectopic pregnancy when using EC pills so it’s important to take a pregnancy test if you experience ongoing symptoms such as missed periods and/or lower abdomen pain for more than 2 weeks following use of EC pills.