Mastitis symptoms usually start with a tender, swollen, warm area in one breast and can progress to fever, chills and flu-like aches.
If one breast suddenly hurts while you are breastfeeding or pumping, it is hard not to worry. Mastitis is a common breastfeeding complication, it is treatable, and in most cases you can keep feeding your baby.
The advice has also changed. In 2022 the Academy of Breastfeeding Medicine (ABM) rewrote its mastitis protocol and moved away from heat, hard massage and extra pumping. This guide covers symptoms, current home care and when to call.
Key Takeaways
Mastitis is breast inflammation on a spectrum: narrowed duct, inflammatory mastitis, bacterial mastitis and, less often, abscess.
Typical symptoms: a painful, swollen, warm area of one breast, redness (harder to see on Black or brown skin), fever and chills.
Current ABM guidance: feed on demand without trying to “empty” the breast, use ice, rest, and skip deep massage.
Not all mastitis is bacterial, so not every case needs antibiotics. Your clinician decides.
Call if symptoms last more than 24 hours or worsen, or you notice a new lump, pus or red streaks.
Table of Contents
Mastitis Symptoms: Early Signs and Flu-Like Symptoms
Quick Answer
Mastitis symptoms usually show up in one breast: a tender, swollen, warm or firm area, pain or burning, and skin redness that is often wedge shaped and can be harder to see on Black or brown skin. Many people also get fever, chills and flu-like aches. The American Academy of Pediatrics (AAP) says to contact your doctor if symptoms continue for more than 24 hours or get worse.
Early signs in the breast: Mayo Clinic lists tenderness or warmth, swelling, thickened tissue or a lump, and pain or burning all the time or while breastfeeding.
Skin color change: Mayo Clinic describes redness, often wedge shaped, that may be harder to see on Black or brown skin. On darker skin, go by warmth, swelling and tenderness.
Flu-like symptoms: StatPearls, a National Institutes of Health (NIH) clinical reference, lists fever, a fast heart rate, chills, muscle aches and feeling unwell.
Other possible signs: MedlinePlus adds one-sided fullness, itching, nipple discharge that may contain pus, nausea, vomiting, and tender or enlarged armpit lymph nodes.
Fever definitions differ: StatPearls uses 100.4 F (38 C) or higher, Mayo Clinic 101 F (38.3 C) or greater. Either way, call.
What Is Mastitis? The Mastitis Spectrum
Mastitis is inflammation of breast tissue. Mayo Clinic notes it sometimes involves an infection, not always. The 2022 Academy of Breastfeeding Medicine (ABM) Clinical Protocol #36 describes a spectrum of conditions that can progress from one to the next:
Stage
What ABM says it is
Typical signs
Ductal narrowing (“clogged” duct)
Microscopic inflammation and narrowing of ducts, not a literal milk “plug”
A firm, tender area without whole-body symptoms
Inflammatory mastitis
Narrowing that persists as inflammation grows. Can occur without infection
A red, swollen, painful region with fever, chills and a fast heart rate
Bacterial mastitis
A progression that needs antibiotics or probiotics to resolve. Not contagious
Similar signs that persist or worsen
Phlegmon
An ill-defined collection of inflamed tissue and fluid, linked to excessive deep massage
A firm, mass-like area
Abscess
An infected pocket of fluid that needs drainage
Growing firmness and redness, often with a fluid collection you can feel
The mastitis spectrum, per ABM Clinical Protocol #36 (2022).
StatPearls says reported rates range from 1% to 33% worldwide. Cleveland Clinic says it is most common in the first three months of breastfeeding.
Mastitis vs Clogged Duct vs Engorgement
Engorgement
Clogged duct
Mastitis
What it is
Swelling as milk comes in, usually days 3 to 5 after birth (ABM)
Narrowing of ducts in one area (ABM)
Breast inflammation that sometimes involves infection (Mayo Clinic)
One breast or both
Usually both (ABM)
One area
Usually an area of one breast (StatPearls)
How it feels
Pain, firmness, swelling (ABM)
A tender, sore lump (Office on Women’s Health)
Red, swollen, painful, warm (ABM, Mayo Clinic)
Fever or feeling ill
Low-grade fever possible (Office on Women’s Health)
Oversupply (hyperlactation): Cleveland Clinic calls it the most common cause. ABM says it leads to congestion and inflammation in the ducts.
Pump issues: ABM notes pumps can injure tissue if the flange size is wrong, suction is too high or sessions run too long.
Skipped feeds, latch trouble, nipple injury: StatPearls lists these along with nipple shields.
Other risk factors: Mayo Clinic lists past mastitis, sore or cracked nipples, pressure on the breast (such as a tight bra), exhaustion or stress, and smoking.
Sources differ on the mechanism. Mayo Clinic and StatPearls point to milk that is not removed well (milk stasis). ABM says the evidence has not proven that, and that mastitis is not contagious or caused by poor hygiene.
What to Do at Home: Current Mastitis Treatment Guidance
These steps come from the ABM 2022 protocol unless another source is named.
Feed on demand; do not try to “empty” the breast: ABM says overfeeding from the sore side or pumping to empty keeps oversupply going and worsens swelling.
If the sore side is too swollen to feed: feed from the other breast and return as swelling settles, hand expressing small amounts for comfort.
Use ice or cold packs: every hour, or more often if you like.
Ask about anti-inflammatory medicine: ABM lists nonsteroidal anti-inflammatory drugs and acetaminophen. Ask your clinician which and how much.
Skip deep massage: and vibrating devices. ABM says deep massage increases inflammation and tissue injury.
Try light lymphatic drainage: Cleveland Clinic compares the pressure to petting a cat, moving toward the armpit and collarbone.
Wear a supportive, well-fitting bra: not a tight one (ABM, Cleveland Clinic).
Rest and drink fluids: (StatPearls, AAP).
Pump only what your baby needs: and do not express and discard milk.
Skip soaks and topical products: such as saline soaks or castor oil.
Why Mastitis Advice Changed in 2022
Heat, hard massage and extra pumping to drain the breast are the older advice. The 2022 ABM protocol moved away from all three:
Extra pumping: ABM says frequent stimulation of a congested breast worsens swelling, pain and redness.
Hard massage: ABM calls it a primary risk factor for phlegmon and abscess.
Heat: ABM says heat widens blood vessels and may worsen symptoms, though some find it comforting. Cleveland Clinic says not to apply heat.
Not every source has caught up: MedlinePlus still lists moist heat, the Office on Women’s Health suggests heat and massage, and Mayo Clinic says to fully drain the breast. If advice conflicts, ask your clinician.
Is It Safe to Keep Breastfeeding With Mastitis?
Yes, in most cases. AAP says to keep nursing and that your baby will not be harmed by drinking your breast milk. ABM states it is safe for children to consume milk from a breast with bacterial mastitis. AAP adds that antibiotics given for mastitis generally do not cause problems for the nursing infant.
With an abscess, MedlinePlus says some women are told to stop temporarily, while ABM says to continue after drainage. Ask your clinician. Feeding on demand includes cluster feeding.
Antibiotics and How Long Mastitis Lasts
Not all mastitis is bacterial, so not all mastitis needs antibiotics. StatPearls says many cases resolve without them, and ABM recommends reserving antibiotics for bacterial mastitis.
When they are used: StatPearls says supportive care is reasonable for the first 24 hours and antibiotics should be started if symptoms do not improve.
Course: ABM lists courses of 10 to 14 days. AAP says to finish the full course.
Feeling better: Cleveland Clinic says relief should begin within 48 to 72 hours of starting antibiotics. AAP says to call if you are not improving within 72 hours.
Overall: Cleveland Clinic says inflammatory mastitis usually resolves within 10 to 14 days, improving dramatically in 24 to 72 hours when managed correctly.
Breast Abscess Warning Signs
ABM and StatPearls report that roughly 3% to 11% of women with acute mastitis develop an abscess. ABM describes progressive firmness and redness, often with a fluid collection you can feel in one well-defined area. Fever may fade, then return. Tell your doctor promptly about:
A firm, painful lump that keeps growing or does not improve.
Pus in your milk or from the nipple.
A fever that returns after you seemed to improve.
An abscess is usually confirmed by ultrasound and must be drained by a clinician (MedlinePlus, ABM). ABM adds that progressive redness with orange-peel skin needs urgent evaluation for inflammatory breast cancer.
Mastitis When Pumping Exclusively or Weaning
Exclusive pumping. ABM advises expressing at a frequency and volume that mimics how a baby feeds, checking flange size, and avoiding high suction and very long sessions.
Mastitis Prevention and Mastitis Outside of Breastfeeding
Pump only what your baby needs (Cleveland Clinic).
Work on latch with a lactation consultant (Mayo Clinic, Cleveland Clinic).
Avoid tight bras and deep massage (Cleveland Clinic, ABM).
Care for cracked nipples early, and wean gradually (MedlinePlus).
Not breastfeeding? Mayo Clinic notes mastitis can happen to people who are not breastfeeding. StatPearls describes periductal mastitis, which is almost exclusively linked to tobacco use. MedlinePlus adds that breast inflammation unrelated to breastfeeding might be due to a rare form of breast cancer, so see a doctor promptly.
Fever or a racing heart lasts more than 24 hours (ABM), or symptoms continue for more than 24 hours or get worse (AAP).
You find a new lump, or home care is not helping (Cleveland Clinic).
You are worse after 24 hours of antibiotics (Cleveland Clinic) or not improving within 72 hours (AAP).
You see pus or blood in your milk, red streaks near the sore area, both breasts look affected, or symptoms came on severely and suddenly (Office on Women’s Health).
Go to the emergency room or call 911 if you feel very ill with possible signs of sepsis. The Centers for Disease Control and Prevention (CDC) lists confusion, shortness of breath, a high heart rate or weak pulse, clammy or sweaty skin, extreme pain, and fever, shivering or feeling very cold, and calls sepsis a life-threatening medical emergency.
See a lactation consultant (IBCLC) for latch pain, oversupply, pump fit or recurring mastitis. Our lactation consultant directory can help. This article is general education, not medical advice.
Frequently Asked Questions
What are the first mastitis symptoms?
Early mastitis symptoms are usually in one breast: tenderness or warmth, swelling, a firm area, and pain or burning. Mayo Clinic also lists wedge-shaped redness, which may be harder to see on Black or brown skin. Fever and chills can follow.
Can I keep breastfeeding with mastitis?
Yes, in most cases. The American Academy of Pediatrics says your baby will not be harmed by drinking your milk. The Academy of Breastfeeding Medicine says milk from a breast with bacterial mastitis is safe. Ask your clinician if you have an abscess.
Will mastitis go away on its own without antibiotics?
Sometimes. StatPearls, an NIH clinical reference, says many cases resolve without antibiotics using rest, fluids, on-demand feeding and ice. It also says antibiotics should be started if symptoms do not improve after 24 hours, so call your doctor instead of waiting.
How long does mastitis last?
Cleveland Clinic says inflammatory mastitis usually gets completely better within 10 to 14 days, and symptoms improve dramatically within 24 to 72 hours when managed correctly. With antibiotics, relief should begin within 48 to 72 hours. Call if you are not improving.
What is the difference between a clogged duct and mastitis?
A clogged duct is a tender, firm area without whole-body symptoms. Mastitis adds a red, swollen, painful region plus fever, chills or flu-like aches. The Office on Women’s Health says that with a fever, you probably have a breast infection, not a plugged duct.
Should I use heat or ice for mastitis?
Current guidance favors ice. The Academy of Breastfeeding Medicine’s 2022 protocol says ice can reduce swelling and pain, while heat may worsen symptoms, though some people find it comforting. Some patient pages still recommend heat, so ask your own clinician.
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