You may notice an occasional lump on one or both breasts while breastfeeding. There are many possible causes for these lumps. Treatment for a lump while breastfeeding depends on the cause.

Sometimes lumps will go away on their own or with home treatment. In other instances, it’s important to see your doctor for treatment.

Read on to learn more about possible causes for lumps while breastfeeding, plus when to seek help.

A lump from a blocked milk duct is a common problem while breastfeeding. You may develop a blocked duct for no apparent reason. Or, it may be due to a number of factors including:

  • your baby isn’t latching well, which can lead to insufficient drainage of milk
  • your clothing is too tight around your breast
  • you’ve gone a long time between feeds

Symptoms of a blocked duct may include:

  • a tender lump that’s the size of a pea to a peach
  • a small white blister on the nipple
  • sensitive breasts

Your baby may also become fussy if you have a blocked duct. That’s because they become frustrated by a reduced flow of milk from the breast with the blocked duct.

Engorgement occurs when your breasts become overly full. It can happen when your milk comes in and your newborn isn’t feeding often enough yet. Or, it can occur later on when your baby hasn’t fed for a while and milk hasn’t been expelled.

If your breasts are engorged, you may notice a lump around the armpit area.

Symptoms of engorgement may include:

  • tightly stretched skin on the breasts that might look shiny
  • hard, tight, and painful breasts
  • flat and taut nipples, making latching difficult
  • low-grade fever

If left untreated, engorgement can lead to a blocked duct or mastitis. If your symptoms don’t improve, see your doctor or a lactation specialist for help.

Mastitis is the inflammation or swelling of breast tissue. It’s caused by an infection, blocked milk duct, or an allergy.

If you have mastitis, you may develop a lump or thickening of breast tissue. Other symptoms may include:

  • breast swelling
  • redness, sometimes in a wedge-shaped pattern
  • breast tenderness or sensitivity
  • pain or burning sensation while breastfeeding
  • chills, headache, or flu-like symptoms
  • a fever of 101 F° (38.3 C°) or higher

A 2008 study found that mastitis occurs in approximately 10 percent of U.S. moms who are breastfeeding. While common, mastitis can be dangerous if left untreated. See your doctor for treatment if you suspect mastitis.

An abscess is a painful, swollen lump. It can develop if mastitis or extreme engorgement isn’t treated quickly or properly. Abscesses are rare among breastfeeding mothers.

If you have an abscess, you may feel a pus-filled lump inside your breast that’s painful to the touch. The skin around the abscess may be red and hot to the touch. Some women also report a fever and other flu-like symptoms.

An abscess requires immediate medical attention. Your doctor may perform an ultrasound to diagnose an abscess. You might need surgery to drain the abscess.

Swollen, tender, or enlarged lymph nodes may be felt under one or both of your arms. Breast tissue extends to the armpit, so you may notice a swollen lymph node as a result of engorgement or an infection, like mastitis.

See your doctor if you’re concerned about a swollen lymph node. They may prescribe antibiotics, or recommend an ultrasound or further treatment.

A galactocele is a benign, milk-filled cyst that develops on the breast. This type of cyst may feel smooth or round. It won’t be hard and tender to the touch. It likely won’t be painful, but it may be uncomfortable.

Milk may express from this type of cyst when it’s massaged.

Your doctor may take a sample of the contents of the cyst, or order an ultrasound to confirm that it’s benign. Galactoceles usually go away on their own when you stop breastfeeding.

Developing breast cancer while breastfeeding is rare. Only about 3 percent of breastfeeding women develop breast cancer during that time.

Notify your doctor if you feel a lump in your breast and also have one or more of these symptoms:

  • nipple discharge (other than breast milk)
  • breast pain that doesn’t go away on its own
  • redness or scaliness of nipple or breast skin
  • skin irritation or dimpling
  • nipple retraction (turning inward)
  • swelling, even if no lump is present

Having these symptoms doesn’t necessarily mean you have breast cancer. But you should still let your doctor know about them. They may want to perform testing or recommend treatment.

If you suspect the lump is caused by a clogged milk duct, you can continue nursing on the affected breast. If this is painful, try switching positions for better drainage.

If your baby doesn’t fully drain the affected breast, use your hand to express milk from it or a pump to prevent further clogging.

The following home remedies may also help:

  • apply a warm, wet compress to the affected breast
  • take warm baths or hot showers several times a day, if possible
  • gently massage the breast to help release the clog before and between feedings
  • apply ice packs to the affected area after breastfeeding
  • wear loose, comfortable clothing that isn’t irritating to your breasts or nipples

See your doctor if the lump doesn’t go away on its own after trying home remedies for a few days. Also, make an appointment with your doctor if:

  • the area around the lump is red and it increases in size
  • you develop a high fever or flu-like symptoms
  • you’re in extreme pain or have extreme discomfort

You can book an appointment with a doctor in your area using our Healthline FindCare tool.

If mastitis or other infection is the cause, your doctor may prescribe antibiotics. They may also recommend an over-the-counter painkiller that’s safe while breastfeeding.

In some cases, you may need additional tests, like an ultrasound or mammogram, to confirm the lump is benign. Your doctor will be able to best advise you on the appropriate treatment option.

In most cases, you can and should continue breastfeeding. If the lump is caused by a blocked duct, breastfeeding can help unclog the duct.

If breastfeeding is painful on the affected breast, you can try to pump breast milk. It’s still safe for your baby to drink the expressed milk.

Most of the time, a lump in your breasts while breastfeeding is due to a clogged milk duct. You can and should continue breastfeeding. But make sure to take care of yourself and get plenty of rest, too.

You can also try home remedies like applying a warm compress before breastfeeding or icing the affected area afterward.

If your breasts become inflamed, or you develop other symptoms of an infection, seek medical help. Your doctor will be able to recommend treatment. A lactation consultant may also be able to help.