Bisacodyl
"I tend to have bowel movements every other day and a week before starting my period is hard for me to go. I tried the Dulcolax suppositories and they work like a charm. I insert the suppository and about 15 minutes later I feel the natural urge to go and I go smooooothly! Yes there is some mild mild cramping but it is not uncomfortable. It burns a little bit and it keeps working for about an hour after so plan ahead. I definitely recommend this product."