cabbage leaves?

Sadie
So I have a 1 week old and I am unable to continue breastfeeding due to my health problems and the medication I take is not safe for breastfeeding. I have been switched to formula for him but my boobs are so extremely full of milk it hurts!! If I pump they will just refill more. I heard putting cabbage leaves in your bra will dry up your milk supply? Does it work? How do I do it? And how long until you noticed a difference? Please no negative comments about my discontinuation of breastfeeding.