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July 22, 2026August 6, 2026
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Is My Bug Bite Infected? How to Tell and What to Do

Tim Montag PA-C Profile 2026By Tim Montag, PA-C, Walk-In Clinic

Mosquitoes, gnats, horse flies, and other biting bugs are part of lake country summers. When a bite swells up big, red, and warm, it can look alarming. Most of the time, it isn’t infected. It’s your body reacting to the bite. Here’s how to tell the difference, how to treat bites at home, and when to come in.

Why do some bug bites swell so much?

Some people have larger reactions to insect saliva than others. A bite can swell to several inches across, feel warm, and look bright red, and still be a normal skin reaction, not an infection. These reactions usually show up within the first day or two and peak around 48 hours.

Signs That a Bite Is Infected

Timing is the biggest clue. Redness and swelling that show up within the first couple of days are almost always a reaction, not an infection. Infections take time to develop, usually three or more days after the bite.

Signs that Point to Infection:

  • Redness or pain that keeps getting worse after 2 to 3 days, instead of better
  • Pus or fluid draining from the bite
  • Red streaks spreading out from the bite
  • Fever or chills

Bug bites: Easing the Itch and Swelling

  •  Wash the bite with soap and water
  • Apply a cold compress for 10 to 15 minutes at a time to ease swelling
  • Use over-the-counter hydrocortisone cream or calamine lotion for itching
  • Take an oral antihistamine if itching is intense; read the label and check with your provider or pharmacist before giving it to a young child.
  • Try not to scratch, since that’s how most bites get infected

When a Bite Needs a Closer Look

  •  The bite is getting redder, larger, or more painful after 2 to 3 days
  • You see pus or red streaks
  • You have a fever
  • A bite near the eye swells the eye shut
  • You find a bullseye-shaped rash or feel flu-like symptoms in the weeks after a tick bite — this can be a sign of Lyme disease, which is common in Minnesota

* Call 911 or go to the Emergency Room if you have hives all over your body, swelling of the face, lips, or tongue, or trouble breathing after a bite or sting. These are signs of a severe allergic reaction.

Not sure? That’s what we’re here for. The Walk-In Clinic at Glenwood Medical Center is open seven days a week.