"took a plan b about 1 hour after unprotected sex. about 15 minutes after taking it i had cramps not sure if it had anything to do with the pill. i read reviews about how women said that after taking plan b their periods changed drastically and they bled heavier and for more days. usually my periods last 4 days and i&#039;m a light bleeder. i got my period last week and nothing changed. very positive experience for me."