Mastitis is an inflamed or swollen area in the breast. This swelling prevents the milk from flowing freely. With a mild case, a mother may feel a small lump. With a more severe case, a large area of the breast may feel swollen or hard. The swollen area may feel tender or painful and it may look red. It may hurt to breastfeed. Most often only one breast is affected. But in rare cases it may occur in both breasts. A mother with mastitis may or may not run a fever.

Mother and Baby


  • Broken skin on the nipple that allows organisms to enter the breast. 
  • Inside pressure from a very full breast.
  • Outside pressure on the breast over time from a too-tight bra, swimsuit, or strap that presses into the breast.


  • Overabundant milk production, which may often leave the breasts feeling full.
  • Diabetes, which puts mothers at higher risk for infections of all kinds. 
  • Feeling very run down.


First, contact your healthcare provider. Ask about taking ibuprofen to reduce the swelling. If you are fever free or have a low-grade fever, your healthcare provider may suggest you do the following to help get rid of the mastitis: 

  • Breastfeed often—every 1.5 to 2 hours during the day and at least every 3 hours at night. 
  • Use breast massage while feeding to help the baby more fully drain the breast. 
  • If that breast still feels full after breastfeeding, express more milk from it.
  • Apply warm compresses to the swollen area 3-4 times a day for 10-15 minutes. It can take up to a week for the swelling to go away. If you are improving, you should feel less swelling every day.

If you notice any of the following, contact your doctor right away. He or she may prescribe an antibiotic if:

  • You do not feel any better within a day or two. 
  • You have a fever of 101°F (38.4°C) or higher. 
  • You see red streaks on your breast, it is feeling hotter, or the swelling is getting worse. 
  • You feel achy and have chills.

This is general information and does not replace the advice of your healthcare provider. If you have a problem you cannot solve quickly, seek help right away. Every baby is different. If in doubt, contact your physician or other healthcare provider.

Download pdf:

Breastfeeding-Mastitis and Thrush