Breast Abscess
A breast abscess is a walled-off collection of pus within the breast, usually developing when mastitis fails to settle or is treated too late. It most often occurs during breastfeeding, where it affects a small proportion of women with mastitis, but it also occurs outside lactation—particularly beneath the nipple in smokers, where it tends to recur. The treatment has changed considerably: drainage with a needle under ultrasound guidance has largely replaced surgical incision, is less painful, leaves no scar, and allows breastfeeding to continue. The most important practical point is that breastfeeding should usually carry on from the affected breast rather than stopping, which is the opposite of what many women assume.
What is it?
An abscess is a collection of pus walled off by the body’s inflammatory response. In the breast, it develops when infection within the tissue is not cleared and the body contains it rather than resolving it.
The usual sequence during breastfeeding begins with milk stasis. Milk that is not effectively removed—because of infrequent feeding, poor attachment, a blocked duct, pressure from a tight bra, or a sudden change in feeding pattern—builds up within a segment of the breast. Pressure forces milk back into surrounding tissue, provoking inflammation. This stage is often called a blocked duct or inflammatory mastitis, and effective milk removal resolves it.
If bacteria, usually entering through a cracked or damaged nipple, colonise this stagnant milk, infective mastitis follows, with fever and systemic illness. Treated promptly with antibiotics and continued milk removal, most cases settle. Where treatment is delayed, where antibiotics are inadequate, or where milk continues to accumulate, infection progresses and the body walls it off into an abscess.
Understanding this sequence explains the two principles that govern treatment: milk must keep moving, and once pus has collected it must be drained, because antibiotics alone penetrate an abscess cavity poorly.
Non-lactational abscess follows a different pattern and deserves separate description, since it behaves differently and is frequently managed badly.
The most common form occurs beneath or beside the nipple and arises from periductal mastitis—inflammation of the ducts just behind the nipple. Smoking is the dominant risk factor and is implicated in the great majority of cases. The mechanism appears to involve damage to the duct lining from substances in tobacco smoke, leading to inflammation, blockage, bacterial overgrowth, and abscess formation. These abscesses are frequently caused by a mixture of organisms including anaerobic bacteria, which differs from the predominantly staphylococcal infection of lactational abscess and affects antibiotic choice.
The defining feature of this form is recurrence. An abscess beneath the nipple in a smoker will very often come back, sometimes repeatedly, and can lead to a mammary duct fistula—a persistent track between the duct and the skin that discharges intermittently and does not heal while the underlying process continues. Nipple inversion develops over time from scarring.
The single most effective intervention is stopping smoking. Without it, recurrence is likely whatever else is done, and this is worth stating plainly rather than implying as general health advice.
Other causes of non-lactational abscess include infection of a skin cyst, infected hair follicle, trauma, diabetes, and immunosuppression. Granulomatous mastitis is an uncommon inflammatory condition that produces recurrent masses and abscesses, can closely mimic cancer, and requires biopsy to diagnose and a different approach to management.
The symptoms develop over days rather than weeks, which is a useful distinguishing feature from most other breast conditions.
A painful, tender lump is the central feature. It is typically firm, may feel fluctuant, and is often exquisitely sensitive to touch.
Redness and warmth of the overlying skin are usual, frequently with a clearly demarcated red area.
Swelling may affect part of the breast or the whole of it.
Fever, chills, and feeling generally unwell are common in lactational abscess and may be absent or milder in non-lactational cases.
Pain is often severe enough to disturb sleep and to make feeding difficult.
Where an abscess has begun to point, pus may discharge through the skin or from the nipple.
One pattern requires specific attention and is the most important diagnostic caution in this area. Inflammatory breast cancer produces redness, swelling, warmth, and skin thickening with an orange-peel texture, and it closely resembles infection. The distinguishing features are that it develops over weeks rather than days, usually without fever, and crucially that it does not respond to antibiotics. Any breast inflammation that has not clearly improved after an appropriate course of antibiotics requires urgent specialist assessment and biopsy rather than a further antibiotic course. This is the single most consequential error in managing breast inflammation, and it is responsible for delayed diagnosis in a condition where delay matters considerably.
Diagnosis is usually straightforward.
Clinical assessment identifies the inflamed, tender area and any fluctuant mass, and establishes whether the woman is systemically unwell.
Ultrasound is the decisive investigation and is central to modern management. It distinguishes mastitis, where tissue is inflamed but no collection has formed and antibiotics alone are appropriate, from an abscess, where a drainable collection is present. It measures the collection, shows whether it is a single cavity or divided into multiple pockets, and guides aspiration in the same appointment. This combination of diagnosis and treatment in one sitting is why ultrasound has transformed the management of this condition.
Culture of aspirated pus identifies the organism and its antibiotic sensitivities, which matters particularly where initial treatment has failed or where resistant organisms are a concern.
Mammography is generally avoided during the acute illness, since compression is painful and the appearances are non-specific. It is performed afterwards in women over 40, and in anyone where the episode has been atypical, to exclude an underlying cancer.
Biopsy is performed where inflammation does not settle as expected, where there is a persistent mass after resolution, where the presentation is atypical, or where inflammatory breast cancer is a consideration. It is also required to diagnose granulomatous mastitis.
Blood tests confirm systemic infection but do not alter the fundamental management, which is drainage and antibiotics.
Important to Know
The two principles of treatment are drainage and continued milk removal, and both are frequently misunderstood. Care is typically provided by primary care clinicians, breast services, and for breastfeeding women, infant feeding specialists whose involvement makes a substantial difference.
Needle aspiration under ultrasound guidance has replaced surgical incision as the first-line treatment for most abscesses. A needle is placed into the collection under local anaesthetic and the pus withdrawn, often with the cavity washed out. It is repeated every few days until the collection resolves, which usually takes two or three procedures. Compared with surgical incision it is less painful, leaves no scar or only a needle mark, does not require general anaesthetic, allows breastfeeding to continue unimpeded, and heals faster. Success rates are high, and this approach now succeeds in the large majority of abscesses including many substantial ones.
Surgical incision and drainage is reserved for specific situations: very large abscesses, those where the overlying skin is thinning or has broken down, those that have failed repeated aspiration, and some multiloculated collections. Where it is needed, the wound is often left open to heal from the base, which takes longer and requires dressing changes.
Antibiotics are given alongside drainage rather than instead of it. An established abscess has a poorly penetrable wall and a core with limited blood supply, so antibiotics alone rarely clear it. The choice differs between lactational abscess, usually caused by staphylococci, and non-lactational abscess, which frequently involves anaerobes and requires broader cover.
The advice about breastfeeding is the point most often got wrong, and it matters. Breastfeeding should continue from the affected breast in almost all cases. Effective milk removal is part of the treatment, not a risk—stopping allows milk to accumulate, which worsens the situation and risks further abscess formation. The milk is safe for the baby, including where antibiotics are being taken, as the antibiotics used are compatible with breastfeeding. Where feeding directly from the affected side is too painful or an aspiration site makes it impractical, expressing from that breast serves the same purpose and should continue until direct feeding resumes.
Many women are told to stop feeding, or assume they must, and this is both unnecessary and counterproductive. Support from an infant feeding specialist or lactation consultant is valuable, both for pain management during feeding and for addressing the attachment or feeding pattern problems that often contributed in the first place.
Pain relief should be adequate. Paracetamol and ibuprofen are both compatible with breastfeeding, and ibuprofen is particularly useful given its anti-inflammatory effect. Warm compresses before feeding help milk flow, and cold packs afterwards reduce swelling and pain.
For recurrent non-lactational abscess, smoking cessation is the treatment. This deserves saying directly rather than mentioning in passing. Without it, abscesses beneath the nipple recur, fistulas form, repeated operations accumulate, and the nipple becomes progressively scarred and inverted. With it, the cycle usually stops. Support for quitting should be offered actively as part of managing the condition rather than as separate general advice.
Where a mammary duct fistula has formed, definitive surgery to excise the affected duct is required, since the track will not heal while it persists. This is best performed once acute infection has settled and, ideally, after smoking has stopped, since results are considerably better.
Granulomatous mastitis is managed differently and should not be treated as straightforward infection. It is diagnosed on biopsy, frequently recurs, and may be managed with observation, corticosteroids, or other immunosuppressive treatment, with surgery used cautiously since wounds heal poorly and recurrence is common.
The caution about inflammatory breast cancer bears repeating as a practical rule: any breast inflammation that has not clearly improved within a short course of appropriate antibiotics requires specialist assessment and biopsy, not another prescription. Redness and swelling developing gradually over weeks without fever should raise this possibility from the outset.
Follow-up matters after resolution. Any residual lump should be reassessed once the inflammation has settled, since an abscess can occasionally develop around an underlying cancer, and the inflammation masks it. In women over 40, mammography after resolution is standard practice.
Prevention in breastfeeding centres on effective milk removal and nipple care. Frequent feeding with good attachment, avoiding long gaps, treating blocked ducts promptly, prompt attention to cracked nipples, avoiding tight bras and pressure on the breast, and seeking help early when feeding is painful all reduce risk. Early treatment of mastitis—within the first day or two—substantially reduces progression to abscess, and women should seek help rather than waiting to see whether it settles.
Care is provided by primary care, breast services, radiology, and infant feeding support. Ultrasound findings and clinical assessment are interpreted together, with the response to treatment being the most important ongoing observation.
Patient education plays an important role. Understanding that drainage is necessary and antibiotics alone are not sufficient, that needle aspiration has replaced surgery for most abscesses, that breastfeeding should continue from the affected breast, that recurrent abscess beneath the nipple will not stop without quitting smoking, and that inflammation not responding to antibiotics needs urgent reassessment all contribute to appropriate care.
Red flag symptoms include breast inflammation that has not clearly improved after an appropriate course of antibiotics, which requires urgent specialist assessment to exclude inflammatory breast cancer; redness and swelling developing gradually over weeks without fever; high fever with rigors, confusion, a racing heart, or low blood pressure, suggesting severe infection requiring urgent care; rapidly spreading redness; skin that is becoming dusky, blistered, or breaking down; a persistent lump remaining after infection has settled; recurrent abscesses in the same area; a persistent discharging opening in the skin near the nipple; and any abscess in a woman who is not breastfeeding and does not smoke, which warrants fuller assessment. These warrant prompt medical evaluation.