Cellulitis from a horsefly bite: what to know

A horsefly bite can leave a small break in the skin. Scratching, rubbing, or contaminated fingers can help bacteria enter that opening. Cellulitis commonly causes an area of skin to become red, warm, tender, and swollen; the redness can extend beyond the original bite. A bite reaction may itch and settle, whereas infection tends to become increasingly painful or expand. These patterns overlap, so appearance alone cannot confirm the diagnosis. See more about [Cellulitis](/conditions/cellulitis/), [Skin Redness](/symptoms/skin-redness/), and [Skin Swelling](/symptoms/skin-swelling/).

Gently wash the bite with soap and water, pat it dry, and avoid squeezing or scratching it. Keep the area covered with a clean dressing if the skin is open. Rest the affected limb in a raised position if swelling is uncomfortable. Marking the edge of redness can help you notice whether it is moving outward, but do not delay care if it is enlarging. A clinician may prescribe antibiotics when cellulitis is diagnosed; use them exactly as directed and do not use leftover medicine.

Arrange same-day medical advice for spreading redness, increasing warmth, worsening pain, pus, or swelling that is not settling. Seek urgent help for [Fever](/symptoms/fever/), chills, faintness, confusion, rapid breathing, or feeling severely unwell, because a serious infection such as [Sepsis](/conditions/sepsis/) can develop. Get medical advice promptly if you have [Type 2 Diabetes](/conditions/type-2-diabetes/), poor circulation, or reduced immunity.

Ask whether the appearance fits cellulitis or a bite reaction, whether the wound needs cleaning or drainage, which antibiotic plan is appropriate, and what change should prompt a return visit. Mention when the bite happened, how quickly the area changed, and any medicine allergies.