When to call

This heading is first deliberately. Untreated mastitis can progress to a breast abscess or to sepsis. NICE Clinical Knowledge Summaries list sepsis, scarring and recurrent mastitis among its complications, and the ABM protocol reports that approximately 3% to 11% of women with acute mastitis will develop an abscess.

Contact your GP, NHS 111, out-of-hours service or maternity unit urgently if:

You are no better within 12 to 24 hours of starting self-care, or you feel worse at any point (NHS).
You have a fever, or feel shivery, shaky or flu-like (La Leche League GB).
A red or darker patch of skin is growing, or you see streaks spreading from it.
There is a lump that does not get smaller as milk is removed, or does not respond to the measures below — this may be an abscess, which needs drainage.
You see signs of infection such as a crusted or oozing nipple wound, or changes in nipple shape, size or colour.
You are not improving within 48 hours of starting antibiotics (NHS).

Call your local emergency number (999 in the UK and Ireland, 911 in the US and Canada, 000 in Australia, 111 in New Zealand) if you become confused or drowsy, are breathing very fast, have mottled or blue-tinged skin, or have not passed urine all day. These are sepsis warning signs.

NICE CKS notes that it is not possible to distinguish clinically between infectious and non-infectious mastitis, but infection is more likely if there is an infected nipple fissure, or if symptoms are not improving or are worsening after 24 hours despite appropriate self-care.

What mastitis is

NICE CKS defines mastitis as "a painful inflammatory condition of the breast which may or may not be accompanied by infection". The NHS lists the symptoms: a swollen area that feels hot and painful to touch, a wedge-shaped lump or hard area, burning pain, nipple discharge that may be white or streaked with blood, and flu-like aches, fever and fatigue. It usually affects one breast and comes on fast.

The 2022 ABM protocol reframed mastitis as a spectrum rather than a single disease: ductal narrowing, inflammatory mastitis, bacterial mastitis, phlegmon, abscess, galactocele and subacute mastitis. That reframing is what drives the treatment changes below. It also explicitly replaces the older ABM protocols #4 (Mastitis) and #20 (Engorgement), which are retired.

What changed in 2022 — and why the old advice can harm

If you have been told to massage the lump hard, apply heat, and feed or pump the affected breast as much as possible, that is the pre-2022 approach. The Academy of Breastfeeding Medicine reversed it.

Deep massage: now advised against. The protocol says to "avoid deep massage of the lactating breast" because it "causes increased inflammation, tissue edema, and microvascular injury", and to avoid electric toothbrushes and other vibrating or massaging devices. It warns that excessive deep tissue massage "may propagate phlegmon formation". What it does support is light lymphatic drainage — sweeping the skin, not kneading tissue. La Leche League GB translates this as using gentle touch "as if you were stroking a cat".
Feeding or pumping harder: now advised against. The protocol says to feed on demand and "do not aim to 'empty' breasts", because overfeeding from the affected breast or pumping to empty "perpetuates a cycle of hyperlactation and is a major risk factor for worsening tissue edema and inflammation". It documents cases where instructions to pump every two hours to "keep the breast empty" drove repeated mastitis.
Heat: largely replaced by cold. The protocol notes heat vasodilates and may worsen symptoms, and that a randomised trial found warm showers and antipyretics did not improve outcomes. Ice can be applied every hour or more often.
The "plug" model: abandoned. The protocol states it "is not physiologically or anatomically possible for a single duct to become obstructed with a macroscopic milk 'plug'". Attempts to squeeze one out are ineffective and cause tissue trauma.
Antibiotics: reserved. "Use of antibiotics for inflammatory mastitis disrupts the breast microbiome and increases the risk of progression to bacterial mastitis."

UK NHS pages have not all been rewritten to match, and some still describe massaging a lump towards the nipple. Where they differ, the ABM protocol is the more recent evidence review — and the NHS mastitis page itself now advises against applying firm pressure, oils or creams to the breast, and recommends cold compresses for 10 minutes every hour.

What to do now

Keep feeding. The ABM protocol states it is safe for children to consume milk from a breast with bacterial mastitis, that mastitis is not contagious, and that women should not be told to express and discard milk.
Feed responsively, and consider starting on the less affected side so you do not overstimulate the inflamed breast.
Ibuprofen and paracetamol. The protocol gives ibuprofen 800mg every 8 hours and paracetamol 1,000mg every 8 hours in the acute setting, if you can normally take them. La Leche League GB notes ibuprofen is often the more useful of the two because it reduces inflammation.
Cold packs between feeds. The NHS suggests 10 minutes hourly.
Rest. Both the ABM protocol and La Leche League treat this as treatment, not advice to be polite about.
Express only for comfort if your breast is uncomfortably full — not to drain it.
Do not wear tight clothing (NHS), and check bag and sling straps.

On supplements, the ABM protocol notes sunflower or soy lecithin 5-10g daily by mouth may be taken to reduce ductal inflammation, and that probiotic data are mixed — a systematic review suggested benefit but no strong recommendation could be made.

If antibiotics are needed

NICE CKS and the ABM protocol both put flucloxacillin or dicloxacillin first line, with cephalexin as an alternative and clindamycin or trimethoprim-sulfamethoxazole second line. The protocol specifies 10 to 14 days; La Leche League GB notes shorter courses make recurrence more likely. The NHS confirms that small amounts of antibiotic passing into breast milk pose no risk to your baby. Routine hospital admission is not necessary unless the presentation demands it.

Preventing the next one

The protocol's own framing is that the underlying cause must be addressed, most often hyperlactation and ineffective milk removal. Practical points: get attachment checked, avoid unnecessary pumping, express only what your baby consumes if you do pump, and treat engorgement early. It also recommends screening for perinatal mood and anxiety disorders, noting that women with a history of anxiety and depression experience higher rates of mastitis symptoms.

Where to get real help

Most breastfeeding problems are solved faster by someone watching a feed than by reading about them. In the UK the National Breastfeeding Helpline is 0300 100 0212 and, as its operators the Breastfeeding Network and the Association of Breastfeeding Mothers state, it is open "24 hours a day, 365 days a year", with support also available in Welsh, Polish, Bengali and Sylheti (nationalbreastfeedinghelpline.org.uk). La Leche League GB runs local groups and a helpline; in Ireland the HSE offers an "Ask our breastfeeding expert" live chat and email service. An IBCLC is an International Board Certified Lactation Consultant, the only internationally accredited lactation qualification — you can check credentials through IBLCE. Your midwife, health visitor or public health nurse can also refer you.

Mastitis