Both these medications are of no real concern for the breastfeeding mother.
Interferon is too big to get into the milk.  Ribavirin, which I didn't know
was being used for Hepatitis C, has been used to treat RSV in very sick,
very small babies.  (With no apparent effect, apparently, as the studies
eventually showed).  As far as I remember, is not well absorbed from the gi
tract, so it was given by inhalation.  Thus, the baby will not get it.  Is
the mother getting it by oral route?

Jack Newman, MD, FRCPC