There is no medication in Canada (and, I would guess) called Moxipen.
Please use generic names, so it is easy to get the information out.

If this is plain penicillin, it is *inappropriate* for use for
mastitis which is almost always due to staphylococcus aureus.
Cloxacillin or other penicillinase resistant penicillin, cephalexin,
which I prefer, clindamycin, amoxycillin-clavulanate, are all possible
effective antibiotics.  Ten days is probably a better length of time.

Mastitis often gets better on inappropriate antibiotics because
mastitis ofte gets better without any antibiotics at all.  Of course,
blocked ducts, which also get better without antibiotics, are often
treated as mastitis.

Generally, if I see a woman with mastitis with symptoms less than 24
hours, I will give her a script for cephalexin 500 mg qid for 10 days,
but I will ask her not to start it yet.  If the symptoms are getting
worse over 8-12 hours, she should start the antibiotic.  If the
symptoms are not worse, but also not better, in 24 hours, she should
start the antibiotic.  I find that somewhat more than 50% of women are
getting better within the 24 hours (not cured, but getting
better--less pain, lower fever, less hard breast etc) without taking
the antibiotics.  I have not yet had a mother develop an abscess with
this regimen (knock on wood).

Jack Newman, MD, FRCPC