So, me and my SO had unprotected sex and I'm on the pill. My fertile window starts tomorrow so we thought to be safe I'd take a plan B. Well, I took it right after sex and got sick an hour later. I didn't know if I threw it up or not so he ran to the drug store and bought another one to have me take. It stayed down. Chances are I had/have two Plan B pills in my system within 3 hours.. chances of it messing up the effectiveness.. ive read it can mess it up or it can cause no issues. I love him and our two year old, were just. Not ready for a second kid just yet.