Mastitis: What Breastfeeding Parents Need to Know (2025 Evidence)

Mastitis is not a reason to stop breastfeeding — it's a reason to feed differently. With the right approach, most cases resolve without antibiotics. The key: less stimulation, not more.

Mastitis affects up to 1 in 5 breastfeeding people in the first months after birth. It is painful, exhausting, and often frightening — arriving with flu-like symptoms that can escalate quickly. For years, the standard advice was to "pump to empty the breast." In 2022, the Academy of Breastfeeding Medicine (ABM) published a landmark revision of Protocol 36 that overturned much of that older guidance [1]. This article reflects that updated evidence.

What Is Mastitis? The Inflammation Spectrum

Mastitis is not a single condition — it is a spectrum [1]:

1. Ductal narrowing ("plugging"): microscopic ductal inflammation and alveolar distension. Not a macroscopic milk "plug" (ducts are innumerable and interlacing — they cannot be blocked by a single clump). May feel like a firm, tender area.
2. Inflammatory mastitis: the narrowing worsens, surrounding inflammation progresses. The breast becomes increasingly red, edematous, and painful — with systemic symptoms (fever, chills, body aches) that can occur even without bacterial infection.
3. Bacterial mastitis: inflammation progresses to an entity requiring antibiotics or probiotics. Presents as spreading cellulitis in a region of the breast.
4. Abscess: a fluid collection that develops in 3–11% of acute mastitis cases, requiring drainage.

The older model treated mastitis as a simple "blocked duct → bacterial infection" binary. The new model recognises that hyperlactation and oversupply are primary driving factors, and that aggressive milk removal makes things worse, not better.

Symptoms

Signs that you may be somewhere on the mastitis spectrum [2][4]:

• A wedge-shaped area of the breast that is red, hot, and tender
• Breast swelling or a firm, painful area
• Fever of 38°C (100.4°F) or above — often with body aches and chills
• Fatigue and feeling like you have the flu
• Burning pain, constant or during feeding

Important: Inflammatory mastitis can cause all of the above — including fever — even without a bacterial infection. This is why treatment approach depends on the stage, not just the presence of fever.

The 2022 Paradigm Shift: What Has Changed

This is the most important section in this article, because the old advice is still widely circulated — and following it can make mastitis significantly worse [1].

What the old advice said

• Pump after every feed to "empty" the breast
• Apply hot compresses before feeding to improve milk flow
• Massage firmly to break up the "blocked duct"

What ABM Protocol 36 (2022) says instead

Do NOT pump to empty the breast. "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." If you are using a breast pump, express only the volume your baby would normally consume — not more [1].

Minimize pump use overall. Breast pumps stimulate milk production without the physiological feedback that infant breastfeeding provides. Pumping can cause trauma to breast tissue and the nipple-areolar complex, and may predispose to dysbiosis of the breast microbiome [1].

Use cold (ice), not heat. Ice reduces blood flow and edema. "Heat will vasodilate and may worsen symptoms" — a randomised controlled trial found that warm showers and antipyretics did not improve mastitis outcomes [1]. Apply cold compresses (a cloth soaked in cold water, or ice wrapped in a towel) for relief.

Feed on demand — do not aim to "empty." Feed your baby when they want, for as long as they want. The goal is physiological breastfeeding, not aggressive drainage. If feeding from the affected side is too painful, feed from the other side and hand-express only enough for comfort [1][2].

Gentle, not aggressive. Avoid deep breast massage, electric toothbrushes, or vibrating devices — these cause increased inflammation, tissue edema, and microvascular injury, and are a primary risk factor for abscess formation [1].

What about cabbage leaves? Studies have not demonstrated cabbage leaves to be more effective than ice. Ice is the evidence-supported choice [1].

Reverse pressure softening (gently pressing the areola inward toward the chest for 1–2 minutes before latching) can help soften a very firm, engorged areola so the baby can latch more effectively [1].

When to See a Doctor

See a doctor promptly if [2][3][4]:

• Symptoms do not improve within 12–24 hours of conservative care (rest, ice, anti-inflammatory medication, feeding on demand)
• You have a fever of 38°C or above with worsening breast redness
• Symptoms have not improved within 48 hours of starting antibiotics
• You can feel a fluctuant lump (a soft, fluid-filled swelling) — this may indicate an abscess requiring drainage
• You are not breastfeeding but have mastitis symptoms

Anti-inflammatory medication: Ibuprofen (an NSAID) reduces edema and inflammation and can provide significant relief [1]. It is safe while breastfeeding at standard doses. Paracetamol/acetaminophen can also help with pain and fever. Ask your pharmacist or doctor about appropriate dosing for your situation.

Antibiotics: When Are They Needed?

Antibiotics are indicated for bacterial mastitis — not for all mastitis [1].

If a doctor determines antibiotics are needed, the first-line agents are typically dicloxacillin or flucloxacillin (for those without penicillin allergy), or cephalexin as an alternative [1]. Your doctor will determine the right antibiotic and duration based on your situation and local resistance patterns — do not ask for a specific one; let the clinical picture guide the prescription.

Complete the full prescribed course. Stopping early risks scarring that could affect milk production and increases the risk of resistant bacteria [3].

If symptoms have not improved within 48 hours of starting the prescribed antibiotic, contact your doctor — the bacteria may be resistant, or you may need a different approach.

Continuing to Breastfeed Through Mastitis

Yes — continue breastfeeding [2][3][4].

• Bacterial mastitis is not contagious to your baby. The breast milk is safe for your baby to drink.
• Stopping breastfeeding abruptly can worsen engorgement, which worsens mastitis.
• Feed from the unaffected breast first if the affected side is very painful, then try the affected side.
• If feeding is too painful, hand-express enough for comfort — do not over-stimulate.

Most hospitals in Thailand have breastfeeding clinics staffed by lactation consultants (ผู้เชี่ยวชาญการให้นมแม่) who can help with latch and positioning during mastitis. Ask your hospital.

Prevention

To reduce the risk of mastitis [1][2]:

• Good latch from the start. A shallow latch increases nipple trauma and the risk of mastitis. If latch is painful, ask for help early — see a lactation consultant.
• Vary feeding positions to ensure different parts of the breast drain physiologically.
• Avoid restrictive bras and tight bra straps. Compression of the breast tissue can promote ductal inflammation.
• Address oversupply early. Hyperlactation (producing significantly more milk than your baby needs) is a primary risk factor for mastitis. If your breasts are always very full and hard, speak to a lactation consultant — the solution is often feeding adjustments, not more pumping.
• Avoid scheduled pumping that creates oversupply. Pump only when separated from your baby or when medically necessary, not to "top up" supply.

Summary

Key takeaways:

1. Don't pump to empty — this worsens the cycle.
2. Cold, not heat.
3. Feed on demand — minimize pump use.
4. Anti-inflammatory medication (ibuprofen) is a first-line tool.
5. See a doctor if no improvement after 12–24 hours, or if fever persists.
6. Keep breastfeeding — it is safe for your baby and helps resolve the inflammation.