What should you know about impetigo on the knee?

Impetigo is a bacterial infection affecting the outer layers of skin. On a knee, it may appear around a graze, insect bite, eczema patch, or area repeatedly rubbed by clothing. Small blisters or sores can break open and form yellow-brown crusts; nearby skin may feel tender or itchy. Crusting skin can have several causes, so an examination helps distinguish impetigo from irritation or another rash. Scratching can move bacteria to nearby areas and under fingernails.

Wash your hands before and after touching the area. Gently clean the knee with mild soap and water, pat it dry, and avoid picking the crust. Keep the lesion covered with a clean dressing when practical, and do not share towels, clothing, bedding, razors, or sports equipment. Wash used linens and clothes regularly. A clinician may recommend topical treatment for a small, limited area or oral treatment when infection is more widespread; use the medicine exactly as prescribed. More about [Topical Antibiotic Therapy](/treatments/medical-dermatology/topical-antibiotic-therapy/) and [Antibiotics For Skin Infection](/treatments/medical-dermatology/antibiotic-therapy-for-skin-infection/).

Arrange medical assessment if the sore is spreading, returning, painful, or not settling with careful hygiene. Seek urgent care for rapidly expanding redness, marked swelling, severe pain, fever, unusual sleepiness, or red streaks moving up the leg. A clinician should also assess a child who seems unwell, an infection near a joint, or skin affected by eczema such as [Atopic Dermatitis](/conditions/atopic-dermatitis/).

Ask whether the appearance fits impetigo, whether a swab is needed, which treatment suits the size and location, and how to protect family members or teammates from contact spread.