"this is the second time i took plan b, and let me tell you....it is effective but messes up your hormones and ph . i took plan b 3 weeks ago oct 16.. 5 days later i got what i thought was my period , that lasted for 17 days. bleeding for 17 days was a nightmare. the first time i took plan b i got my period 5 days later and then again every 2 weeks for 2 months followed by a yeast infection. now i think my period is over finally after 17 days i am spotting very lightly with yet another yeast infection. never once in my life have i had a yeast infection except for after taking plan b. i personally will never take it again  ."