Midwives brew

So my dr called me today to see if anything happened after she did the membrane sweep yesterday and I told her that nothing happened yet. So she told me to look up the midwives brew and do that today. I told her ok sure I’ll look up the ingredients and go to the store now to buy them and then I’ll do it when I get home... so I looked it up and it has castor oil in it!!!! I’ve heard horrible things about that and now idk what to do.. I don’t want to risk anything at all. Should I call her back and tell her I’m not comfortable with the oil? I’m shocked she recommended this and now I don’t even trust her as my OB 😩