Re: why do tea bags do for nipple care when breastfeeding?
In my unit, we do not recommend tea bags. We do recommend using lanolin-based ointments for nipple soreness between nursing (and not washing off) , as well as washing ONLY with warm water, not soap, and letting the breasts dry naturally in open air, as possible. Also most helpful is expressing a tiny bit of colostrum/milk and rubbing it on the nipple---very therapeutic.
Another thing we teach is proper latching of the newborn in breastfeeding is most critical in preventing severe nipple soreness and even bleeding/blistering. I can't say I would want to use anything that would contribute to dryness of the nipples like tannins, etc.
I always recommend patients seek help from a certified Lactation Consultant or La Leche League group in their area if they are having severe nipple soreness or problems breastfeeding. These resources are amazing and so informative. Probably TMI here, but I hope this helps.