Herpes simplex mastitis: what to know

Herpes simplex mastitis is an uncommon breast infection that can cause painful blisters or ulcers and needs clinical assessment, especially during breastfeeding. Lesions around the nipple or areola can expose a baby to infection through direct contact, so feeding plans should be discussed promptly with a clinician.

The breast may become tender, with grouped fluid-filled blisters that break into shallow sores. Fever, fatigue or swollen glands may occur. This differs from more typical milk-stasis or bacterial inflammation, and [Breast Pain](/symptoms/breast-pain/) can have many causes. A visual examination and, when appropriate, a swab help guide treatment; do not squeeze or open blisters.

Cover lesions with clean clothing or a dressing, wash hands before and after touching the breast, and avoid letting the baby touch affected skin. Do not apply unprescribed creams or herbal products to an open lesion. Ask urgently about whether to pause feeding from the affected breast and how to maintain milk supply; a [Lactation Consultation](/treatments/pregnancy-and-birth-care/lactation-consultation/) can help with a safe feeding plan. Antiviral medicine may be prescribed after assessment.

Contact a clinician promptly for new blisters, ulcers, breast redness with fever, rapidly increasing pain or a baby who may have touched a lesion. Seek urgent help if you feel severely unwell, the infection is spreading quickly, or the baby develops fever, poor feeding, unusual sleepiness or skin or eye lesions. [Painful Breastfeeding](/symptoms/painful-breastfeeding/) may need a different assessment when no blisters are present.

Could these lesions be herpes or another infection? Is testing needed? Should I pause feeding from one breast, and how can I protect milk supply? Does my baby need assessment or monitoring?