My gf recently had a minor hemorrhoid and took preparation H (to which she had an allergic reaction as a 13-year old many years ago). A week after stopping the Prep H use, she developed skin growths between the vagina and anus. They look like they could be warts but I also read allergic reactions could cause skin tags. We're monogamous and I've never noticed anything unusual on my penis. Could the growths be related to the hemorrhoid and Preparation H or is it likely warts?

It's probably not warts. I would stop the Prep H though. The active ingredient is phenylephrine, and it can cause an allergic reaction as she found out. Allergic reaction can do weird things to the skin.

Go to the drugstore and get some zinc oxide (5 - 25%). They will probably have a couple different brands. Start using that instead. In addition, have her start taking daily warm baths. With those two things, you'll see a marked improvement in a few days.