Mupirocin for bug bites: what to know

A fresh bite often produces a small itchy or swollen area as the immune system reacts to saliva or venom. Mupirocin does not treat that itch or the original bite reaction. Infection is more concerning when the area becomes increasingly warm, painful, swollen, or wet, or when pus and spreading redness appear after the skin has been scratched.

Some people develop dark marks after inflammation settles; this is called post-inflammatory hyperpigmentation and does not mean bacteria remain in the skin. The appearance of a bite alone cannot identify the insect or prove infection.

Gently wash the area, use a cool compress, and avoid scratching. Keep fingernails short and cover the spot lightly if rubbing is unavoidable. An oral antihistamine may help itch for some people, while a topical corticosteroid may be considered for an inflamed bite when a clinician or pharmacist says it is suitable. Use mupirocin only when prescribed for suspected bacterial infection, and follow the directions rather than using an old tube.

Arrange medical advice when redness is spreading, pain is increasing, pus appears, or fever develops. Seek urgent help for swelling of the mouth or throat, breathing difficulty, dizziness, faintness, or a rapidly generalised allergic reaction. A bite near the eye, a bite from an unknown source, or worsening symptoms in a young child also deserves prompt assessment.

Ask whether the skin is infected, which symptoms are from the bite reaction, whether an antihistamine or topical corticosteroid is suitable, and how to care for any dark mark after healing.