I took Plan B 5-6 days ago. I had no immediate side effects. Starting yesterday my breast have become very tender and mild cramping. Today both have become worse. How long do these symptoms generally last? Os it common the symtoms take a few days to start. I am unsure what to expect, as this is my first time taking this. When I read up on it, most sites state only a few days right after it is taken. It was like the symptoms have been delayed in my case. I will also advise I was ovulating when my oops occurred.