Mastitis vs Blocked Ducts, How to Tell the Difference & What to Do in Perth

You’ve woken up with a red, hot, hard area in your breast. Is it a blocked duct? Is it mastitis? Should you push through and feed, or call the doctor? These questions are terrifying at 3am with a hungry baby, and getting the answer right matters.

As a lactation consultant working across Perth, I deal with both conditions regularly. Here is a clear, practical breakdown, and exactly what to do in each case.

What Is a Blocked Duct?

A blocked (or plugged) duct happens when milk isn’t draining properly from part of the breast,

Signs of a blocked duct:

• A firm, tender lump in one area of the breast
• The skin over the lump may be slightly pink or red
• No fever, or only a very mild low-grade temperature (below 38.5°C)
• You feel tired and sore in the breast, but not generally unwell
• Pain is localised to the lump area and may improve after feeding

What Is Mastitis?

Mastitis is an inflammation of the breast tissue that may or may not involve infection. It can develop from a blocked duct that isn’t resolved, or it can occur without a prior blockage.

Signs of mastitis:

• A wedge-shaped area of redness, warmth, and swelling on the breast
• Fever of 38.5°C or higher
• Flu-like symptoms, chills, body aches, fatigue, headache
• Breast pain that feels more severe and is not relieved by feeding
• You feel genuinely unwell, not just sore

The Key Difference at a Glance

The clearest distinguishing factor is systemic symptoms. A blocked duct stays local, it hurts and there may be mild warmth, but you don’t feel sick in your whole body. Mastitis makes you feel like you have the flu. The flu-like symptoms are the red flag that tells you this has moved beyond a simple blockage.

◆ Important: Mastitis that is left untreated can progress to a breast abscess, which requires surgical drainage. Always take mastitis seriously and seek treatment promptly.

What to Do for a Blocked Duct, Home Management

In most cases, a blocked duct can be resolved without medical intervention if caught early:

1. Continue breastfeeding frequently, offer the affected side first to maximise drainage
2. Position the baby so their chin points toward the lump (this helps drain that area)
3. Apply warmth to the area before feeding (a warm flannel or shower) to help milk flow
4. Gentle massage TOWARD the nipple, do not aggressively press or massage hard as this can worsen inflammation
5. Rest as much as possible (easier said than done with a newborn, but important)
6. Stay well hydrated

Most blocked ducts resolve within 24–48 hours with this approach. If it hasn’t cleared after 48 hours, or you develop a fever, treat it as mastitis and seek help.

What to Do for Mastitis

Keep feeding, do not stop

This is the most critical thing to know about mastitis: stopping breastfeeding makes it worse, not better. Milk stasis is the enemy. Continue feeding as frequently as possible from the affected breast. Your baby cannot get sick from your milk, even if mastitis progresses to infection.

See your GP for antibiotics

Infectious mastitis requires antibiotics. In Australia, the first-line treatment is typically dicloxacillin or flucloxacillin for 10–14 days. If you are allergic to penicillin, alternatives are available. Contact your GP promptly, do not wait to see if it resolves on its own if you have a fever and flu symptoms.

Pain relief

Ibuprofen (if not contraindicated) is both a pain reliever and anti-inflammatory, making it more helpful than paracetamol alone for mastitis. Both are safe to use while breastfeeding. Always confirm with your pharmacist or GP.

Call a lactation consultant

Antibiotics treat the infection, but they don’t fix the underlying cause. If mastitis keeps coming back, a lactation consultation is essential to identify why. Common causes include a poor latch, a blocked duct that isn’t fully clearing, an oversupply, or an undiagnosed tongue tie causing inefficient drainage.

When to Go to Hospital

• If you develop a fever above 39.5°C that isn’t responding to paracetamol/ibuprofen
• If you notice a fluctuant (fluid-filled) lump that is getting larger, this may be an abscess
• If your symptoms are rapidly worsening despite starting antibiotics
• If you feel severely unwell

Physiotherapy for Blocked Ducts and Mastitis

Therapeutic ultrasound administered by a physiotherapist can help break up stubborn blocked ducts and reduce mastitis inflammation. In Perth, Genesis Physiotherapy in Wembley is well-known for this service and offers same-day appointments for breastfeeding mums in most cases.

The ABA National Breastfeeding Helpline is available 24/7 on 1800 686 268. Trained volunteer counsellors can provide phone and sometimes in-person support. This is a great first point of call for general questions.

Recurrent Mastitis, Breaking the Cycle

If you’ve had mastitis more than once, something is driving the recurrence. Common causes include:

• A persistent latch issue causing inefficient drainage
• Oversupply leading to engorgement and back-pressure
• Abruptly missing feeds or long gaps
• Returning to work without a pumping schedule
• Underwire bras or tight clothing compressing ducts
• A tongue or lip tie causing incomplete drainage

I offer home lactation consultations across Perth specifically to help identify and break the mastitis cycle. Most mums are surprised at how quickly the pattern can be reversed with targeted support..