How can you tell the difference between a blocked duct and mastitis?

Mastitis is due to an infection (almost always due to bacteria rather than other types of germs) that usually occurs in breastfeeding mothers. However it can occur in any woman, even if she is not breastfeeding and can even occur in newborn babies of either sex. Nobody knows exactly why some women get mastitis and others do not. Bacteria may enter the breast through a crack or sore in the nipple but women without sore nipples also get mastitis and most women with cracks or sores do not. Mastitis is different from a blocked duct because a blocked duct is not thought to be an infection and thus does not need to be treated with antibiotics. With a blocked duct, a mother has a painful, swollen, firm mass in the breast. The skin overlying the blocked duct is often red, but less intensely red than the redness of mastitis. Unlike mastitis, a blocked duct is not usually associated with fever, though it can be. Mastitis is usually more painful than a blocked duct, but both can be quite painful. Thus seeing the difference between a “mild” mastitis and a “severe” blocked duct may not be easy. It is also possible that a blocked duct goes on to become mastitis, so things become even more complicated. However, without a lump in the breast, there is no mastitis or blocked duct for that matter.