Mastitis

Overview

Mastitis is an inflammation (swelling and redness) of the breast tissue, often caused by an infection. It most commonly happens in women who are breastfeeding, but it can also occur in non‑breastfeeding women and, rarely, in men.

Mastitis is fairly common in breastfeeding women. About 1 in 5 breastfeeding women will experience it at some point. It is less common outside of breastfeeding.

Mastitis most often affects breastfeeding women, especially in the first few months after childbirth. However, it can also occur in women who are not breastfeeding, and rarely in men.

Symptoms

Common symptoms

• A painful, red, swollen area on one breast – often in a wedge shape
• The breast feels warm or hot to the touch
• A high temperature (fever) over 38°C (100.4°F)
• Feeling generally unwell, achy, or tired

Symptoms in children

• Mastitis in children is very rare. If a child has a red, swollen, painful breast with fever, it could be an infection. Contact a doctor promptly.

Symptoms in older adults

• In older adults, mastitis can be a sign of an underlying condition. Symptoms are similar: breast redness, swelling, heat, and pain, possibly with fever.

Causes

Main causes

• Bacteria (usually Staphylococcus aureus) entering the breast through a cracked or sore nipple
• Milk building up in the breast (milk stasis) and not being drained properly, which can lead to inflammation

Risk factors

• Breastfeeding, especially if the baby has difficulty latching
• A cracked or sore nipple
• Skipping feeds or having long gaps between feeds
• Wearing tight bras or putting pressure on the breast

When to see a doctor

See a doctor urgently if:

• You have a red, painful area on your breast and a fever over 38°C (100.4°F)
• You think you have an abscess (a pus‑filled lump) – this needs draining
• Symptoms do not improve after 24 hours of self‑care

Book a routine appointment if:

• You have a breast lump that does not go away after your period or after finishing breastfeeding
• You have recurrent episodes of mastitis

Diagnosis

Your doctor will ask about your symptoms and examine your breast. They may also ask about your feeding patterns if you are breastfeeding.

Tests that may be done

• Usually no tests are needed. If the diagnosis is uncertain, your doctor may recommend a breast ultrasound to check for an abscess.
• Rarely, a sample of breast milk may be sent to a lab to identify the bacteria causing the infection.

What to expect at your appointment

The doctor will press gently on the breast to check for tender spots or lumps. They will also check your temperature. The exam is usually not painful, though it may be a little uncomfortable. The whole visit typically takes less than 30 minutes.

Treatment

Treatment for mastitis focuses on relieving symptoms, clearing the infection, and keeping the breast drained. Most cases get better within a few days.

Self-care at home

• Continue breastfeeding or expressing milk frequently (every 2‑3 hours) – this is the most important step to clear the blockage
• Use warm compresses on the sore area before feeds to help milk flow
• Take over‑the‑counter pain relievers (like paracetamol or ibuprofen) – check with your pharmacist or doctor first
• Drink plenty of fluids and rest as much as possible

Medical treatments

If your symptoms do not improve after 24 hours, your doctor may prescribe an antibiotic that is safe to take while breastfeeding. It is important to finish the full course, even if you feel better. Do not stop the medicine early unless your doctor says so.

When is surgery considered?

If an abscess (collection of pus) forms, it may need to be drained. This is usually done by a doctor using a needle (aspiration) or, rarely, by a small surgical cut under anaesthetic. This is a minor procedure and does not usually require an overnight stay.

Living with this condition

While you have mastitis, try to get extra rest. Continue breastfeeding or expressing regularly. It may help to start feeds on the unaffected side to let your milk flow, then switch to the affected side. Avoid tight bras or clothing.

Lifestyle tips

• Keep the sore breast well‑drained – do not skip feeds
• Wear a well‑fitting, supportive bra that is not too tight
• Wash your hands before touching your breasts, especially if you have cracked nipples

Diet and exercise

Eat a balanced diet to support your immune system. Drink extra fluids. Avoid vigorous exercise until you feel better, but gentle walking is fine.

Mental health and emotional wellbeing

Mastitis can be painful and tiring, which may add stress to the already demanding role of caring for a new baby. It is normal to feel frustrated or anxious. Talk to your partner, family, or a healthcare professional about how you are feeling. If you feel very low, speak to your doctor or a mental health support service.

Prevention

While not always preventable, you can reduce your risk by making sure your baby latches well, feeding on demand, alternating breasts, and treating any cracked nipples immediately. Avoid long gaps between feeds and do not wear tight bras.

Complications

If left untreated

• A breast abscess (a collection of pus) that may need to be drained
• Severe infection that spreads deeper into the breast tissue
• Rarely, the infection can spread to the blood (sepsis), which is serious

Long-term outlook

With proper treatment, most people with mastitis feel better within a few days and fully recover within a week or two. Even if an abscess forms, it can be treated successfully. Mastitis does not cause breast cancer, and having it once does not mean you will get it again, though some women do have recurrent episodes. With good breastfeeding support, many women can continue to breastfeed successfully.

Find support

Local organisations

• NHS (UK) ↗ · United Kingdom
• La Leche League International ↗ · International

Helplines

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