Yeast infections – where did it come from this time? I used to ask myself this. I tried to narrow down the culprit by watching my diet, using cotton underwear and not using anything with perfumes on my vagina. It never occurred to me that using a mild soap while in the shower could cause one. I just assumed that with all that water washing over me the soap would rinse off. I have done my own test in the shower, using a mild soap on only the outside of my vagina. I fill up the 2lip cup with the clean running shower water and with my legs slightly open I place the 2lip cup externally over the opening of my vagina. With a soft upward pushing motion, the 2lip cup cleans the inside using only water. I have been doing this for the past two years (using my prototypes for testing) and no longer have yeast infections.