Speaking (unfortunately) from personal experience- poison ivy on the breasts
and nipples is no joy jump! Therer is no contraindication for breastfeeding
once the breasts have been washed well with soap and water, chances are the
baby won't have a reaction unless s/he has previous exposure to poison ivy,
but the exposure from breastfeeding on a breast with the oil may sensitize
him/her for the next exposure. Topical/oral steroids are generally
considered compatible with breastfeeding, comfort measures such as oatmeal
soaks help some. A tincture of time is necessary, it is amazing how long
this rash can last! It took over 2 weeks of severe discomfort to resolve. It
is itchy and painful.  OK- how does one get poison ivy on the breasts- I
suppose rolling naked in the woods might do it, but so will pulling up dead
vines in the winter and then touching your breast to nurse without washing
your hands well- when you are working hard in the yard and your toddler just
needs a sip, it doesn't make sense to go all the way into the house. I will
say that it is not as painful as primary herpes on the breast nor as
shingles, but more so that hand foot and mouth disease, exzema and yeast. :)
Cathy Liles