Symptoms of mastitis can appear suddenly. They may be in one or both breasts. Symptoms may include:

• Breast tenderness or warmth.
• Breast swelling.
• Thickening of breast tissue, or a breast lump.
• Pain or a burning feeling all the time or while breastfeeding.
• Skin redness, often in a wedge-shaped pattern. The redness may be harder to see on Black or brown skin.
• Feeling ill.
• Fever of 101 degrees Fahrenheit (38.3 degrees Celsius) or greater.

When to see a doctor

See your healthcare professional if you have breast symptoms that worry you.

Milk that is trapped in the breast is the main cause of mastitis. Other causes include:

• A blocked milk duct. If a breast doesn't empty all the way during feedings, one of the milk ducts can get clogged. Then milk backs up, leading to breast infection.
• Germs going into the breast. Germs from the skin's surface and baby's mouth can enter the milk ducts. This can happen through a crack in the skin of the nipple or through a milk duct opening. Germs can grow in milk that stays in a breast that isn't emptied.

Risk factors for mastitis include:

• Having a history of mastitis.
• Having sore or cracked nipples.
• Putting pressure on a breast that restricts milk flow. Wearing a tight bra or using a tight seat belt can cause pressure.
• Not nursing correctly.
• Being overly tired or stressed.
• Eating poorly.
• Smoking.

Mastitis that isn't treated or that is due to a blocked duct can cause pus to build up in the breast. This is called an abscess. An abscess most often needs to be drained surgically.

To avoid this complication, talk with your healthcare professional as soon as you get symptoms of mastitis. You may need to take a course of antibiotics.

Before you start breastfeeding, think about meeting with a breastfeeding specialist, called a lactation consultant. This can help you avoid complications such as mastitis.

Lower your chances of getting mastitis by following these tips:

• Feed your baby on demand or let out milk with your hand, called expressing, often.
• Fully drain the milk from your breasts while breastfeeding.
• Let your baby empty one breast all the way before switching to the other breast during feeding.
• Change the position you use to breastfeed from one feeding to the next.
• Make sure your baby latches on well during feedings.
• If you smoke, talk with your healthcare professional about how to quit.

Your healthcare professional does a physical exam and asks about your symptoms and medical history. You might have a breast ultrasound. Your healthcare professional might take out, called aspirate, some of the fluid in your breast. A culture of this fluid can help find the best antibiotic for you.

A rare form of breast cancer, called inflammatory breast cancer, also can cause redness and swelling that might be confused with mastitis. Your healthcare professional may suggest a mammogram or an ultrasound or both.

If your symptoms don't go away after you take a full course of antibiotics, you may need a biopsy to make sure you don't have breast cancer. Be sure to follow up with your healthcare professional after you've taken all the antibiotics.

Mastitis treatment might involve:

• Antibiotics. If you have an infection, a 10-day course of antibiotics is most often needed. Take all the medicine. This lowers the risk of the infection coming back. If your mastitis doesn't clear up after taking antibiotics, contact your healthcare professional.
• Pain relievers. You can try a medicine available without a prescription such as acetaminophen (Tylenol, others) or ibuprofen (Advil, Motrin IB, others).

It's safe to keep breastfeeding if you have mastitis. Breastfeeding helps clear the infection. Weaning your baby suddenly might make your symptoms worse.

You might see a specialist in breastfeeding, called a lactation consultant, for help and support. Advice on the best way to breastfeed might include:

• Don't let your breasts fill too much between feedings.
• Try get your infant to latch on well. This can be hard when your breast is swollen.
• Letting out a small amount of milk by hand before breastfeeding might help. This is called expressing.
• Lightly massage the breast while breastfeeding or pumping milk. Start at the affected area and move down toward the nipple. Do not press hard or squeeze.
• Make sure your breast drains all the way during breastfeeding. If you have trouble emptying your breast, put a warm, moist cloth on the breast before breastfeeding or pumping milk.
• Breastfeed on the affected side first. This is when your infant is hungrier and sucking harder.
• Change your breastfeeding positions.
• Drink plenty of fluids.

To help yourself feel better:

• Don't let your breasts fill up with too much milk between breastfeeding sessions.
• Put a cool cloth or ice pack on your breast after breastfeeding.
• Wear a bra that supports your breasts.
• Rest as much as you can.

You may be sent to an obstetrician-gynecologist. For problems related to breastfeeding, you may be referred to a lactation consultant.

What you can do

Make a list of:

• Your symptoms, including any that may not seem to be linked to the reason you made the appointment, and when they began.
• All medicines, vitamins and supplements you take, including doses.
• Key medical information, including other conditions you have.
• Questions to ask your healthcare professional.

Questions to ask your doctor

• Will my mastitis clear on its own or do I need treatment?
• What can I do at home to relieve my symptoms?
• How might my condition affect my baby?
• If I keep breastfeeding, is the medicine you're prescribing safe for my baby?
• How long will I have to take the medicine?
• What are the chances that the infection will come back? How do I lower my risk of it coming back?

Be sure to ask all the questions you have.

What to expect from your doctor

Your healthcare professional might ask you:

• Are your symptoms in one or both breasts?
• How bad is your pain?
• How do you breastfeed?
• Have you had mastitis before?