Mastitis is an inflammation of breast tissue that can become very painful and, if bacteria are involved, lead to an infection. It occurs most often in women who are breastfeeding, though anyone can develop it, even if they aren’t nursing.

How common is it?

Mastitis is relatively frequent in breastfeeding mothers, especially within the first three months after giving birth. While less common in people who aren’t nursing, it can occasionally occur in anyone.

Signs and symptoms

Mastitis usually starts as inflammation of breast, so the affected breast may feel sore, swollen, warm, or firm. You might notice:

A burning or sharp pain that worsens during nursing.

A tender or hard lump.

Redness or streaks on the skin.

Flu-like symptoms such as fever or chills if an infection develops.

Many women also notice that the breast feels overly full or engorged, which can be uncomfortable.

Why mastitis develops

The most common trigger is an oversupply of milk, which causes swelling in the surrounding tissues. That swelling can compress the milk ducts and slow the flow of milk, leading to engorgement and inflammation. If bacteria enter the milk ducts—often through small cracks in the nipple—an infection may follow.

An untreated infection can sometimes form a pocket of pus called an abscess, which requires medical drainage.

Risk factors

You’re more likely to experience mastitis if you’re producing more milk than your baby needs or if you miss feeds or pumping sessions. Sudden changes in your baby’s feeding pattern or weaning can also contribute.

Diagnosis

A healthcare provider usually makes the diagnosis after examining your breasts and discussing your symptoms. If you’re not breastfeeding, they may order imaging tests to rule out other conditions.

Treatment options

For inflammation without infection:

Cold therapy: apply an ice pack or a bag of frozen vegetables for about 10 minutes at a time while lying on your back, allowing swelling to drain toward the lymph nodes.

Gentle lymphatic massage: use light, sweeping strokes (like softly petting a cat) from the breast toward the armpit or collarbone to move fluid and reduce swelling.

Pain relief: over-the-counter anti-inflammatory medicines, if approved by your healthcare provider, can ease pain and decrease swelling.

Reverse pressure softening: lightly press the area around the nipple with your fingertips and gently push fluid away to make latching easier.

Wear a supportive but non-restrictive bra to avoid adding pressure.

Avoid:

Deep or aggressive breast massage

Heat packs or soaking the breast

Overpumping or feeding more than usual, which can increase milk production and worsen inflammation.

If inflammation doesn’t improve, your provider may prescribe antibiotics to clear a bacterial infection. Most people feel better within two to three days of starting treatment, though the infection typically clears completely in about 10 days.

Possible complications

If left untreated, mastitis can lead to a breast abscess that requires drainage by a doctor. Always seek medical attention if you develop fever, worsening pain, or spreading redness.

Continuing to breastfeed

It is safe—and recommended—to keep nursing when you have mastitis. Your breast milk will not harm your baby and actually contains antibodies that can help protect them. Milk supply may dip temporarily while your body fights the infection, but it usually recovers.

Prevention tips

• Feed or pump only what your baby needs; avoid “emptying” your breasts excessively.

• Make sure your baby has a good latch so milk flows efficiently.

• Don’t skip nursing sessions, and pump if you must be away.

• Avoid tight bras or devices that put extra pressure on the breast.

When to call your doctor

Seek medical care if:

• Pain, swelling, or redness worsens or doesn’t improve after a few days of home care.

• You notice a new lump or nipple discharge.

• You have fever, chills, or flu-like symptoms.

• You don’t feel better after 24 hours of antibiotics.

Outlook

With prompt care, mastitis usually clears within one to two weeks and rarely causes long-term problems. Early recognition and gentle treatment can help you recover quickly and continue breastfeeding comfortably.