>>Does thrush occur unilaterally?<< Yes; I've seen this several times. It was entirely appropriate for baby and mom to be treated orally when baby had the yeasty (I assume) diaper rash. Nystatin for the nipples is more effective for some women than for others, and sometimes, even with good preventative treatment, a ductal yeast infection will occur. It sounds like your mother has one of these, and the best treatment that I know of to reach this is diflucan [fluconozole], preferably the 7 or 10 day dose and not the "one shot" vaginal type treatment. I have also heard of complications with an untreated apparent ductal yeast infection, and the milk blister may be the result of that. Along with the diflucan, you might consider suggesting that the mother nurse the baby in a position that places the chin to point towards the affected area; have her do this at least a couple of times a day to promote good drainage. Laying baby on the floor and crawling over him sometimes makes this easier to accomplish, though also awkward and fatiguing at times; the gravity is a plus, too! I had a mom with recurrent mastitis and milk blisters that came and went. We didn't have the yeast issue, and I had her do the above nursing gymnastics, plus put neosporin ointment on her nipple where the blister occurred, a small amt after every feed. She only had one reoccurrence, and then it all went away for good.... this was after 2-3 mos of chronic problems. -Lisa Marasco, IBCLC [log in to unmask], [log in to unmask]