When should I call my GP for mastitis?

Call your GP today if you have a hot, red, hard area on your breast together with flu-like symptoms such as fever, chills, or aching. If self-care measures have not produced clear improvement within 12 to 24 hours, you need antibiotics. Also seek urgent care if you have pus or discharge from the nipple, a fever above 38.5 degrees C that is not coming down, or a soft, fluctuant lump developing in the breast, which may indicate an abscess.

Mastitis: symptoms, causes and how to treat it

Q: Can I keep breastfeeding if I have mastitis?

Yes, and it is important that you do. Continuing to feed or express from the affected breast is one of the most effective treatments for mastitis. Stopping suddenly makes mastitis worse and significantly raises the risk of developing a breast abscess. Your milk is safe for your baby, even if you are on antibiotics.

Q: How long does mastitis take to clear up?

With appropriate treatment including continued feeding and antibiotics where needed, most cases of mastitis resolve within 10 to 14 days. Non-infectious inflammatory mastitis without fever often clears faster, within a few days of good breast drainage and warmth. If symptoms have not improved significantly within 48 hours of starting antibiotics, go back to your GP.

Q: What antibiotics are used for mastitis?

In the UK, GPs most commonly prescribe flucloxacillin for mastitis because it is effective against Staphylococcus aureus, the most common causative bacteria. If you are allergic to penicillin, erythromycin or clarithromycin may be used instead. Both flucloxacillin and the alternative antibiotics are considered safe to take while breastfeeding. Complete the full course even if you feel better sooner.

Q: Can mastitis come back?

Yes. Some people experience recurrent mastitis, particularly if the underlying cause such as a poor latch, infrequent feeding, or cracked nipples is not addressed. Each episode should be reviewed with your GP. If you have three or more episodes in a short period, your GP may refer you for an ultrasound to rule out an underlying structural cause and assess whether longer antibiotic treatment is needed.

Q: What is the difference between a blocked duct and mastitis?

A blocked duct causes a tender lump in the breast and may cause local redness, but you generally feel well in yourself. Mastitis builds from the same process but involves significant breast inflammation and causes flu-like symptoms such as fever, chills, and body aches. The key marker is how you feel overall: if you feel suddenly ill as well as having a sore breast, it has progressed to mastitis and you need to call your GP.

Breastfeeding · Updated July 2026 · All articles

If you have woken up feeling as though you have flu, with a hot, hard, red patch on your breast, you may have mastitis. It is one of the most common and distressing breastfeeding problems, and many people experience it in the middle of the night when everything feels at its worst. You are not doing anything wrong, and with the right steps it can be treated.

Mastitis is inflammation of breast tissue. It can be caused by milk building up in the breast (non-infectious mastitis) or by a bacterial infection (infectious mastitis). Both need prompt attention. If you have a painful, red, hot area on your breast along with flu-like symptoms such as fever, chills, or body aches, call your GP today. Do not wait 24 hours before seeking help. If it is the weekend or out of hours, contact NHS 111.

Symptoms to look for

Mastitis usually develops quickly. Symptoms can appear within hours and include:

A hard, hot, swollen, wedge-shaped area on one breast, often in the upper outer part
Redness of the skin over the affected area
Tenderness or pain in the breast that may be constant, not just during a feed
A hard lump within the inflamed area
Flu-like symptoms: fever (temperature of 38 degrees C or above), chills, shivering, tiredness, and muscle aches

The flu-like symptoms can arrive before the breast soreness is obvious. If you feel suddenly and severely unwell during the first weeks of breastfeeding, check your breast. The combination of feeling ill and a sore, hot breast together is classic mastitis.

Most mastitis occurs in the first six weeks after birth, but it can develop at any point during breastfeeding, including months later. It almost always affects one breast at a time.

When to call your GP (do this today)

Contact your GP the same day if you have symptoms of mastitis. Seek urgent care via NHS 111 or your nearest urgent treatment centre if your GP is not available, or if:

Your fever is high (above 38.5 degrees C) and not coming down
You have pus or blood-stained discharge from the nipple
A soft, fluid-filled lump is developing within the red area of your breast
Your symptoms are rapidly getting worse
Self-care has not produced clear improvement within 12 to 24 hours

Go to A&E or call 999 if you develop a rapidly spreading red streak from the breast, a high fever with confusion or extreme shivering, or you feel seriously unwell. These are signs that a breast abscess may have formed or that infection is spreading, both of which need urgent treatment.

What causes mastitis

The most common starting point for mastitis is milk stasis: milk that is not being drained from the breast regularly or effectively. When milk builds up in the ducts and surrounding tissue, the area becomes swollen and inflamed. This is the non-infectious stage of mastitis. If bacteria then enter, usually through a crack or sore on the nipple, the area becomes infected and infectious mastitis develops.

The bacteria most often responsible is Staphylococcus aureus, which lives on the skin and enters through small breaks in the nipple. This is why cracked or damaged nipples significantly increase the risk.

Common reasons that milk stasis leads to mastitis include:

A poor latch that prevents efficient drainage during a feed
Suddenly going longer between feeds (skipped feeds, sleeping through, or starting to wean)
Pressure on a particular area of the breast, from a tight bra, car seat strap, or sleeping position, blocking a duct
Oversupply in the early weeks, when milk comes in faster than your baby can drain it
A tongue tie affecting your baby's ability to feed efficiently

From blocked duct to mastitis: how it progresses

Many cases of mastitis begin as a blocked duct. A blocked duct feels like a tender lump in the breast with some local discomfort. You feel well in yourself. At this stage, prompt drainage and warmth can often resolve it before it progresses.

If a blocked duct is not cleared, the surrounding tissue becomes inflamed. When flu-like symptoms appear alongside the breast tenderness, the condition has moved into mastitis. The key question is always how you feel overall: if you feel ill as well as having a sore breast, that matters.

Acting early at the blocked duct stage can interrupt this progression. If you notice a firm, tender lump, offer extra feeds from that side, try massage toward the nipple, and apply warmth before feeding. If you also feel unwell or develop a fever, call your GP rather than waiting to see if it resolves on its own.

What to do first

Alongside contacting your GP, there are steps you can take immediately that make a genuine difference to how quickly mastitis resolves.

Keep feeding or expressing from the affected breast

This is the single most important thing. Many people instinctively want to rest the affected breast or stop feeding from it, but this makes mastitis significantly worse. Milk that stays in the breast feeds the inflammation and, if infected, creates a better environment for bacteria to multiply. The WHO, NHS, and La Leche League International all state clearly that you should continue to breastfeed from the affected side.

Your milk is safe for your baby during mastitis. The infection is in the breast tissue, not in the milk itself, and breastfeeding does not harm your baby. If feeding from the affected side is too painful to start a feed, you can express a little by hand first to soften the area, then offer the breast.

Feed more frequently

Offer the affected breast first at each feed, when your baby's sucking is strongest. Aim to feed at least eight times in 24 hours. If your baby will not feed enough to drain the breast, use a breast pump or hand express after feeding to ensure the breast is as empty as possible.

Warmth before, cold after

Applying warmth to the breast before a feed, using a warm flannel or a warm shower, helps the milk flow more easily. This makes drainage more effective during the feed. After the feed, a cool pack or a cold damp cloth can ease discomfort and reduce swelling. Do not apply intense heat for long periods between feeds, as it can worsen inflammation.

Gentle breast massage

During a feed or while expressing, use gentle circular massage on the hard area, working toward the nipple. Avoid deep or forceful pressure, which can irritate already inflamed tissue. The aim is to help move milk toward the ducts and encourage drainage, not to break up the lump by force.

Rest and fluids

Your body is fighting inflammation and possibly infection. Rest as much as you can, drink plenty of water, and take paracetamol or ibuprofen (both are safe while breastfeeding) to manage fever and pain. Ibuprofen has some anti-inflammatory effect and may be particularly helpful, but check with your pharmacist or GP if you have any reason to avoid it.

Antibiotics for mastitis

If mastitis is caused by a bacterial infection, or if non-infectious mastitis has not improved within 12 to 24 hours of the self-care steps above, you need antibiotics. Do not wait it out beyond this window.

In the UK, GPs most commonly prescribe flucloxacillin, which is effective against Staphylococcus aureus. If you are allergic to penicillin, erythromycin or clarithromycin are used instead. Both options are safe to take while breastfeeding.

It is important to complete the full course of antibiotics, even if you feel much better within two or three days. Stopping early increases the risk of the infection not clearing fully and of antibiotic resistance. Continue breastfeeding throughout the antibiotic course. There is no reason to stop.

If your symptoms have not improved clearly within 48 hours of starting antibiotics, or they get worse, contact your GP again. You may need a different antibiotic, or investigations to rule out an abscess.

Risk of a breast abscess

If mastitis is not treated promptly or adequately, a pocket of pus can form within the breast tissue, called a breast abscess. This is uncommon when mastitis is treated early, but it is a serious complication. Signs of an abscess include:

A soft, fluctuant (fluid-filled) lump within the inflamed area
Severe, localised pain that does not improve with antibiotics
Fever that continues despite taking antibiotics
Pus or blood-stained discharge from the nipple

If you suspect an abscess, go to A&E or an urgent treatment centre. Abscesses usually need to be drained, either by needle aspiration (guided by ultrasound) or, in more advanced cases, by a small surgical procedure. Breastfeeding from the affected breast may need to pause while an abscess is treated, though most people can continue on the other side and return to feeding from the affected breast once it has healed.

Blocked duct, mastitis and engorgement: a brief comparison

These three conditions often feel similar and can be confused, but they have different causes and need different responses.

Engorgement affects the whole breast, which becomes overfull, hard, and uncomfortable. It is most common when milk first comes in, usually days two to four after birth. You do not feel systemically unwell. The treatment is frequent feeding and gentle hand expression to relieve pressure.
Blocked duct causes a localised firm, tender lump in one area of the breast. There may be some redness over the lump. You feel well in yourself. The treatment is frequent feeding and gentle massage toward the nipple. A blocked duct can clear within one to two days with good management.
Mastitis involves significant breast inflammation with redness, heat, and hardness, plus flu-like symptoms: fever, chills, and body aches. You feel ill. It requires prompt action and, in most cases, antibiotics.

How to prevent mastitis

No prevention strategy eliminates all risk, but several factors consistently reduce it:

Get the latch right early. A good latch is the most effective single factor in preventing mastitis. A baby that is latched well drains the breast efficiently. Ask your midwife, health visitor, or a breastfeeding support worker to observe a full feed if you are not sure.
Do not skip or delay feeds. Letting the breast become very full raises the risk of milk stasis. If you are going to miss a feed, express at the usual time.
Treat cracked nipples promptly. Cracked nipples are the main entry point for bacteria. Lanolin or expressed breast milk can be applied after feeds. If cracks are not healing, ask for support to check the latch and whether tongue tie may be a factor.
Choose supportive, not restrictive, breast support. Avoid bras or tops that press hard on any area of the breast, particularly overnight. An ill-fitting underwired bra is a common culprit.
Change feeding positions. Alternating positions ensures different areas of the breast are drained at each feed, reducing the chance of a duct blocking in one spot.
Wean gradually. If you are reducing feeds or stopping breastfeeding, doing so gradually over days to weeks gives your body time to reduce supply and reduces the risk of mastitis from sudden engorgement.

Frequently asked questions

Can I keep breastfeeding if I have mastitis?

Yes. Continuing to feed from the affected breast is one of the most important treatments. Stopping makes mastitis worse and raises the risk of a breast abscess. Your milk is safe for your baby throughout.

When should I call my GP?

Call today if you have a hot, red, hard area on your breast and feel unwell with fever or chills. If symptoms have not clearly improved within 12 to 24 hours of self-care, you need antibiotics. Go to A&E if you develop a soft fluctuant lump in the breast, a high fever with worsening symptoms, or a rapidly spreading red streak.

How long does mastitis take to clear up?

With continued feeding and the right antibiotics, most cases resolve within 10 to 14 days. Mild inflammatory mastitis without infection often settles faster. If you are on antibiotics and things have not improved clearly within 48 hours, go back to your GP.

What antibiotics are used for mastitis?

Flucloxacillin is the most common first choice in the UK. If you are allergic to penicillin, your GP may prescribe erythromycin or clarithromycin. All are safe while breastfeeding. Complete the full course.

Can mastitis come back?

Yes. Recurrent mastitis is not unusual, especially if the underlying cause (such as a poor latch or cracked nipples) has not been addressed. If you have three or more episodes, ask your GP for a referral to investigate further.

What is the difference between a blocked duct and mastitis?

A blocked duct feels like a tender lump but you feel well in yourself. Mastitis builds from the same process but causes flu-like symptoms alongside the breast pain. If you feel ill as well as having a sore breast, call your GP rather than managing it at home.

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