Nipple pain is caused by two major things: a poor latch and a bacteria called staph aureus.  Other things can cause pain: vasospasm (or a constriction of the blood vessels of the nipple), Reynaud's phenomenon (where the nipple turns white, red, then blue) , pump trauma, certain skin conditions, tongue-tie, pregnancy,  and other infections, like yeast.  It's not meant to be an all-inclusive list, but you get the idea.  Lots of things cause pain.

But we do know , from lots of studies, that the vast majority of pain is due to a poor latch (and probably vasospasm after the latch is fixed ) and staph aureus.  And the staph can't get there unless the skin is broken and the nipple is injured, so back to the latch. The point is, bacteria are much more common as a cause of nipple pain. But we blame yeast for everything. 

So, a little on yeast.  The typical symptoms described for yeast are redness, itching and burning of the nipples and shooting pain in the breast.  The diagnosis is made by looking at the nipple and correlating it with symptoms.  No culture is done and if it was, it's probably useless.  Lactoferrin in human milk makes culturing yeast from milk very difficult unless the right technique is used.  And you have to culture nipples very carefully and interpret the results carefully.  Many studies have shown that women with no nipple pain will often grow yeast on a skin culture. It also doesn't "invade" tissues; in normal people it stays on the surface of tissues.  That's why the diagnosis of "ductal yeast" has never made sense to me.  The yeast would have to invade to cause that pain.  Dr. Hale's study (below) calls into very serious question whether ductal yeast exists. 

Yeast is found naturally in everyone's GI tract, and helps with the health of the GI tract.  If you culture random people, you can get  Candida  (which I'm going to continue to call yeast) from the mouth of 31-55% of them. Yeast is everywhere. It only becomes a disease -causing agent when something else is wrong.  For example, you got antibiotics and killed the good bacteria in your gut.  Then the yeast overgrow and have a party.  Or, you have  AIDS, are receiving chemo or have otherwise really, really messed up your immune system.

In terms of treatment, there are no ("gold-standard" )randomized controlled trials.  Fluconazole (Diflucan) is often used, and can cause blood vessel constriction and make vasospasm symptoms worse.  Expert opinion says treat mom and baby even if one has no symptoms, but again, no data supports that practice. Sounds messy to me and maybe we should know we are treating yeast before we actually treat it.  Because if we treat yeast and it isn't yeast, we are keeping that mother in pain unnecessarily.  And pain casues weaning.  We need to get this right, for the sake of the dyad.

I haven't treated yeast for nipple pain in ages in my own practice because I know (and hopefully you do too now) that the overwhelming causes of nipple pain are related to poor latch and staph.  I use Muciprocin (Bactroban) for the staph and fix the latch.  But the women I care for who come to see me talk of "resistant yeast" and have been on numerous courses of yeast-treating things with no relief.  How many times do we need to treat the same thing before we begin to think we have the wrong diagnosis?

In my practice, these symptoms are often oversupply, where the baby bites and pulls back, injuring the nipple. Some are missed, significant tongue-tie.  I've diagnosed more than a few women with Reynaud's phenomenon.  I've seen pump trauma, usually from incorrect use (too high of a suction) or an old motor (too low of suction) - that resolves with a new or no pump.  I've found a few pregnancies (much to the surprise of the mom...eek.)  One mother was pumping in her car in January and I'm pretty sure her "yeast" was frostbite. 

I'm not saying nipple yeast doesn't exist.  But it shouldn't  be our first or or even second guess. 

I hope you can access this study from Dr. Hale because it's excellent: http://www.liebertonline.com/doi/pdfplus/10.1089/bfm.2008.0144

Jenny Thomas, MD, IBCLC, FAAP, FABM