What are the symptoms of mastitis (inflammation of the breast tissue) in the left breast?

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Last updated: March 14, 2025View editorial policy

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From the Guidelines

Mastitis in the left breast typically presents with symptoms such as redness, swelling, warmth, and tenderness in the affected area, along with flu-like feelings including fever, chills, body aches, fatigue, and headache, as noted in the most recent study 1. The symptoms of mastitis can vary, but common signs include:

  • Redness and swelling in the affected breast
  • Warmth and tenderness in the breast
  • Pain or discomfort that can be continuous
  • Flu-like feelings, including fever (often above 101°F or 38.3°C), chills, body aches, and fatigue
  • Headache
  • A wedge-shaped red area on the breast
  • Discharge from the nipple or a hard, swollen lump Mastitis occurs when milk ducts become blocked and infected, often due to inadequate milk drainage, cracked nipples allowing bacteria entry, or pressure on the breast from tight clothing or sleeping position, as described in 1. If you experience these symptoms, it is essential to:
  • Continue breastfeeding or expressing milk from the affected breast to help clear the blockage
  • Apply warm compresses before feeding
  • Ensure proper latch technique
  • Contact your healthcare provider promptly, as antibiotics (typically dicloxacillin or cephalexin 500mg four times daily for 10-14 days) are often necessary to treat the infection and prevent complications like breast abscess, as recommended in 1. It is crucial to seek medical attention if symptoms persist or worsen, as mastitis can lead to more severe complications if left untreated, as noted in 1.

From the Research

Symptoms of Mastitis

The symptoms of mastitis, including when it occurs in the left breast, can be identified through various studies.

  • Common symptoms include a swollen, red, hot, and painful breast, accompanied by systemic symptoms such as fever 2.
  • Focal tenderness in one breast, along with fever and malaise, are also typical presentations of mastitis 3, 4.
  • Overlying skin erythema or hyperpigmentation may also be present 4.
  • It is essential to note that mastitis can occur in any breast, including the left breast, and the symptoms can be similar regardless of the affected breast.

Diagnosis and Treatment

  • Diagnosis of mastitis is usually clinical, based on the presence of symptoms, and does not require laboratory tests or imaging in most cases 3, 4.
  • Treatment includes changing breastfeeding technique, often with the assistance of a lactation consultant, and may involve antibiotics effective against Staphylococcus aureus 3, 2.
  • Effective milk removal is a crucial part of the treatment and may make antibiotics unnecessary in some cases 2, 4.
  • Continued breastfeeding is generally encouraged in the presence of mastitis and does not pose a risk to the infant 3, 2, 4.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

[Treatment of mastitis in general practice].

Tidsskrift for den Norske laegeforening : tidsskrift for praktisk medicin, ny raekke, 2003

Research

Management of mastitis in breastfeeding women.

American family physician, 2008

Research

Mastitis: Rapid Evidence Review.

American family physician, 2024

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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