"after reading so many reviews in the past couple of weeks, i felt i needed to write one given my unusual experience.  i had unprotected sex the first week of december, i took plan b within 12hrs and felt completely fine.  4 days later i bled very heavily for 4 or 5 days, and figured i safe.  then my period never came, took 2 pregnancy tests both were negative but i got so paranoid once i was a week late i went to the doctor and had a blood test, also negative, but with still no period and &quot;pregnancy symptoms&quot; i was still very concerned. finally 11 days late i started my period.  plan b can definitely throw your system very out of whack, so moral of the story if you&#039;re anything like me try and relax!"