You don't need documentation. Only common sense. Mastitis is almost always caused by staphylococcus aureus. Almost all staphylococcus aureus is resistant to amoxycillin (in most areas). Therefore why on earth would someone prescribe amoxycillin for mastitis? It is like prescribing antibiotics for a viral infection (which is done alot too). You don't need documentation. My approach to mastitis. If the mother has had symptoms for less than 24 hours (arbitrary on my part), I will give her a script for cephalexin 500 mg qid, but ask her not to start immediately. If her symptoms (pain, area of hardness, fever) are getting worse over 8-12 hours (also arbitrary), then start the cephalexin. If, in 24 hours, there is no worsening, but no improvement, then start. I find that easily 50% of women are actually improving by 24 hours, *without* the antibiotics, and then don't need to start. The symptoms are not gone, but they are lessening. So why amoxycillin? Well if 50% get better, then it will look as if amoxycillin has worked. If, in addition, every blocked duct is treated as mastitis, as many physicians do, it will look as if the amoxycillin worked. Just like giving amoxycillin for a cold. Seems to work, doesn't it? Jack Newman, MD, FRCPC