Breast Care A-Z · Condition · MASTITIS

Mastitis and breast abscess

also: mastitis, breast infection, breast abscess, lactational mastitis, non-lactational mastitis, periductal mastitis · pronounced ma-STY-tis

Mastitis is inflammation of the breast, usually from infection, and a breast abscess is a collection of pus that can form if mastitis does not settle. You may have breast pain and redness that hasn't cleared with first-line treatment, or been told an abscess has formed.

Quick answers

Should I stop breastfeeding if I have mastitis?

No. Continuing to breastfeed (and to express milk on the affected side) helps clear the mastitis. Stopping breastfeeding usually makes mastitis worse. The milk is safe for the baby; the antibiotics typically used are also safe in breastfeeding.

How long do antibiotics take to work?

Most patients with simple lactational mastitis feel better within 48 hours of starting antibiotics. Symptoms not improving by then warrants ultrasound to look for an abscess. The full antibiotic course (7–10 days) should be completed even if you feel better quickly, to prevent recurrence.

Will the abscess come back?

Lactational abscesses, once treated, usually do not recur during the same breastfeeding episode if the underlying cause has been addressed. Periductal abscesses are more likely to recur, particularly in smokers, and sometimes need a more involved surgical approach (excision of the affected ducts) to break the cycle.

Mastitis and Breast Abscess -- Breastory Encyclopaedia Plate LIX Plate covering lactational mastitis, periductal mastitis, and breast abscess: presentation, management, and IBC mimicry. ONCOLOGY · BENIGN BREAST CONDITIONS PLATE LIX mastitis and breast abscess lactational mastitis · periductal mastitis · breast abscess infective and inflammatory conditions of the breast, most common in breastfeeding women, requiring prompt diagnosis to prevent progression to abscess FIG 01 -- Breast cross-section: Mastitis (left) vs Breast Abscess (right) MASTITIS diffuse inflammation ABSCESS walled pus collection i -- blocked lactiferous duct ii -- diffuse inflammatory infiltrate (skin erythema overlying) iii -- abscess wall (pyogenic membrane) iv -- pus collection (fluctuant) v -- skin erythema and oedema Mastitis: no discrete collection -- treat with antibiotics Abscess: walled fluid cavity -- USS aspiration +/- drainage The clinical distinction between mastitis and abscess drives management. Antibiotics alone for mastitis; ultrasound-guided aspiration for abscess. Always exclude IBC if no response at 1 week. Lactational vs Non-lactational Lactational: 2-3 weeks post-partum Organism: Staph aureus (commonest) Continue feeding: Yes -- reduces abscess risk Non-lactational: Periductal mastitis Association: Smoking, squamous metaplasia Pattern: Mixed organisms, subareolar Management pathway Mastitis Antibiotics + continue feeding Developing abscess USS-guided aspiration (repeat prn) Established abscess Surgical drainage if aspiration fails FIG 02 -- Mastitis vs Breast Abscess: clinical comparison Feature Mastitis Breast Abscess Presentation Diffuse warm, red, tender breast Fluctuant tender lump Systemic Fever, malaise Fever, high WBC USS finding Diffuse inflam., no fluid Fluid collection, thick wall First-line Rx Antibiotics (flucloxacillin) Aspiration + antibiotics Breastfeeding Continue (reduces abscess risk) Continue if possible Organism Staph aureus Staph aureus, mixed organisms Incidence 2-10% breastfeeding women 5-11% of mastitis cases Recurrence Low if treated early Higher (periductal type) Biopsy Not required If persistent -- exclude cancer IBC mimicry Resolves with antibiotics Resolves with drainage FIG 03 -- Causes of breast infection Type Cause Management Lactational mastitis Duct stasis, Staph aureus Flucloxacillin + continue feeding Lactational abscess Progression from mastitis USS aspiration + antibiotics Periductal mastitis Smoking, squamous metaplasia Antibiotics +/- surgical excision Non-lactational abscess Mixed organisms, periareolar Aspiration / drainage Post-surgical infection Wound, seroma infection Wound care + antibiotics Cellulitis Skin entry point Antibiotics Hidradenitis Axillary/IMF apocrine glands Dermatology referral Granulomatous mastitis Idiopathic / autoimmune Steroids / biopsy first Diabetic mastopathy Diabetes-related fibrosis Biopsy to exclude malignancy FIG 04 -- Clinical pathway: mastitis and abscess management 1 Presentation: pain, erythema, fever 2 Clinical assess: lactating? 3 USS: mastitis vs abscess 4 Antibiotics +/- aspiration 5 48h review: biopsy if no response 6 Wound care / drain if recurrent FIG 05 -- Related conditions and procedures Lactational mastitis Lactational abscess Periductal mastitis (non-lactational) USS-guided aspiration Surgical drainage (Hilton technique) Recurrent subareolar abscess FIG 06 -- Key statistics 2-10% of breastfeeding women develop mastitis [1] ~5-11% of mastitis cases progress to abscess [2] Aspiration successful in ~85% of breast abscesses [3] IBC must be excluded if no antibiotic response at 1 week [4] References 1. Amir LH et al. Mastitis in breastfeeding. BMJ 2014;349:g6137 2. Bharat A et al. Breast abscess outcomes. Am J Surg 2009 3. Christensen AF et al. Ultrasound-guided aspiration. Acta Radiol 2005 4. NICE NG101. Early breast cancer 2023 5. WHO. Mastitis -- causes and management 2000 Clinically authored by Dr Fiona Tsang-Wright , FRCS (Gen Surg) GMC 4549831 · ORCID 0000-0003-4801-026X
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Definition
Mastitis is inflammation of the breast tissue, often (though not always) associated with breastfeeding; a breast abscess is a localised collection of pus that has formed when mastitis has not settled with antibiotics.

Common questions The questions patients ask first

Should I stop breastfeeding if I have mastitis?
No. Continuing to breastfeed (and to express milk on the affected side) helps clear the mastitis. Stopping breastfeeding usually makes mastitis worse. The milk is safe for the baby; the antibiotics typically used are also safe in breastfeeding.
How long do antibiotics take to work?
Most patients with simple lactational mastitis feel better within 48 hours of starting antibiotics1. Symptoms not improving by then warrants ultrasound to look for an abscess. The full antibiotic course (7–10 days) should be completed even if you feel better quickly, to prevent recurrence.
Will the abscess come back?
Lactational abscesses, once treated, usually do not recur during the same breastfeeding episode if the underlying cause has been addressed. Periductal abscesses are more likely to recur, particularly in smokers, and sometimes need a more involved surgical approach (excision of the affected ducts) to break the cycle.
Could this be cancer?
Most cases of red, swollen breast are infection, not cancer. The key check is whether the symptoms settle on antibiotics within 48–72 hours. If they do not, prompt imaging and biopsy are arranged to exclude inflammatory breast cancer — a rare but important diagnosis.

Mastitis is inflammation of the breast tissue, often (though not always) associated with breastfeeding; a breast abscess is a localised collection of pus that has formed when mastitis has not settled with antibiotics.

Both conditions are common and well-treated when picked up early. The standard pathway is prompt antibiotics, ultrasound to confirm whether an absce1ss has formed, and ultrasound-guided drainage if it has — surgical drainage in an operating theatre is rarely needed in modern practice. The key red flag is mastitis that does not settle within 48–72 hours of antibiotics, which warrants prompt assessment to exclude both an abscess and (rarely) inflammatory breast cancer.

Orientation Why you might be reading about this

You may be experiencing breast pain and redness that has not settled with first-line treatment, or you have been told an abscess has formed. This page explains what mastitis and breast abscess are, when they need urgent assessment, and what modern treatment looks like — particularly that needle aspiration has largely replaced surgical drainage.

Related terms: Inflammatory breast cancer · Breast pain · Breast ultrasound

Two patterns Lactational versus non-lactational

Mastitis falls into two main groups based on context:

Lactational mastitis

Mastitis during breastfeeding affects around one in ten breastfeeding women. The usual cause is a combination of milk stasis (a blocked duct or incomplete breast emptying) and bacteria entering through the nipple, leading to inflammation and infection of an area of breast tissue.

Symptoms typically include:

  • A red, warm, painful area in the breast — often a wedge-shaped patch on one side.
  • Pain on feeding from the affected side, sometimes with reduced flow.
  • Flu-like symptoms — fever, chills, body aches, fatigue.
  • A tender lump within the inflamed area, sometimes growing over a day or two.

Non-lactational mastitis

Mastitis outside of breastfeeding has a different set of causes:

  • Periductal mastitis — inflammation around the major ducts behind the nipple, often associated with smoking. Can become recurrent and is sometimes associated with a mammary duct fistula (a small connection between an inflamed duct and the skin).
  • Skin infections of the breast, particularly in the inframammary fold or armpit.
  • Sebaceous cysts that have become inflamed.
  • Idiopathic granulomatous mastitis — an uncommon non-infective inflammatory condition that can mimic abscess or inflammatory breast cancer; diagnosed on core biopsy and managed differently from infective mastitis.
  • Idiopathic granulomatous mastitis — an uncommon non-infective inflammatory condition that can mimic abscess or inflammatory breast cancer; diagnosed on core biopsy and managed differently from infective mastitis.
  • Unusual organisms (TB, actinomyces) — uncommon in the UK but worth considering in patients from endemic areas.
  • Inflammatory breast cancer — rare but important not to miss, particularly when redness and inflammation do not settle as expected on antibiotics.

Treatment How treatment works

The general pathway is the same for both lactational and non-lactational mastitis:

Step 1 — Antibiotics

A 10–14 day course of antibiotics tailored to the likely organism1. For lactational mastitis, flucloxacillin 500 mg four times daily is standard first-line (erythromycin or clarithromycin if penicillin-allergic). For non-lactational mastitis, mixed organisms including anaerobes are common — co-amoxiclav is first-line, or clarithromycin/erythromycin plus metronidazole if penicillin-allergic. Most cases improve within 48–72 hours.

Step 2 — Ultrasound if not settling

Mastitis that does not improve within 48–72 hours of antibiotics warrants ultrasound1 to look for an abscess that has formed. This is the key step in the pathway — the symptom-not-settling check is what distinguishes simple mastitis from an abscess that needs drainage, and from the rarer inflammatory breast cancer presentation.

Step 3 — Drainage if an abscess is found

The standard treatment for a breast abscess in modern UK practice is ultrasound-guided needle aspiration combined with continued antibiotics1. The abscess is decompressed with a fine needle under local anaesthetic; the procedure takes 10–15 minutes. Repeated aspirations every few days are often needed; most abscesses settle over 2–4 weeks.

Surgical drainage in theatre is rare in modern practice and reserved for abscesses that cannot be controlled by aspiration — for example, very large abscesses, thick loculated pus, or cases that recur despite repeated aspiration.

For background on the practice’s pathway, see mastitis and breast abscess service page.

When to escalate When mastitis is NOT just mastitis

The diagnosis to make sure is not missed is inflammatory breast cancer (IBC) — see inflammatory breast cancer. The pattern that warrants concern:

  • Mastitis that does not settle within 48–72 hours of appropriate antibiotics1.
  • Persistent redness, swelling, and skin thickening of the breast despite treatment.
  • A patient outside of the breastfeeding context, particularly older patients.
  • Peau d’orange (orange-peel skin appearance) — a stronger indicator of IBC than infection.

In any of these situations, prompt imaging (mammogram, ultrasound, often MRI) plus skin biopsy and core biopsy of any underlying mass are arranged, even when infection seems the more likely diagnosis.

Breastfeeding Continuing breastfeeding through mastitis

For lactational mastitis, continuing to breastfeed from the affected breast helps clear the inflammation. Stopping breastfeeding usually makes mastitis worse, not better. The bacteria involved are not harmful to the baby through breast milk; the milk itself is safe. This is one of the most common counter-intuitive points in breastfeeding support.

When to seek care When to seek care

⚠ A breast that is becoming increasingly red, hot, or swollen, especially with rising fever or feeling very unwell, needs prompt assessment — same-day or out-of-hours rather than waiting for a routine appointment. Untreated breast infection can occasionally progress quickly.

For breastfeeding mothers, the threshold for seeking advice is low — even mild symptoms warrant prompt review, because early antibiotics prevent escalation to abscess.

Resources Further reading

Sources & guidance

Every figure on this page is anchored to a published source. Tap a number in the text or below to jump to the reference.

  1. patient NHS. Mastitis. nhs.uk. 2024 https://www.nhs.uk/conditions/mastitis/ Cited for: First-line management of mastitis, antibiotic course duration, when to escalate.
  2. review Robertson FM, Bondy M, Yang W, et al. Inflammatory breast cancer: the disease, the biology, the treatment. CA: A Cancer Journal for Clinicians. 2010 ;60(6):351-375 doi:10.3322/caac.20082 Cited for: Inflammatory breast cancer prevalence (1-5%), clinical presentation, neoadjuvant chemotherapy standard.