How Do You Know If an Insect Bite Is Infected?

An insect bite is likely infected if the redness around it is spreading (not shrinking), the area is increasingly warm and swollen, you see pus or cloudy drainage, red streaks extend outward from the bite, or you develop a fever. Normal bites cause localized redness and itching that improves over a few days. Infected bites get worse, not better. A telemedicine doctor can evaluate your bite on video, determine whether you need antibiotics, and send a prescription to your pharmacy — often within the hour.

Normal Bite Reactions vs. Infection

Understanding the difference helps you know when to seek care:

Normal Reaction (No Treatment Needed)

Redness confined to a small area around the bite
Mild swelling that peaks within 24-48 hours then decreases
Itching that responds to antihistamines or hydrocortisone cream
A small bump or welt at the bite site

Signs of Infection (See a Doctor)

Expanding redness — The red area grows larger instead of smaller over 24-48 hours. Drawing a circle around the redness with a pen and checking again in a few hours can help track this.
Increasing warmth — The skin around the bite feels noticeably warm or hot to the touch.
Pus or drainage — Yellow, green, or cloudy fluid seeping from the bite.
Red streaks — Lines extending outward from the bite toward the body, which can indicate the infection is spreading to the lymphatic system.
Fever — Temperature above 100.4 degrees F, especially with a worsening bite.
Hardening or swelling — The tissue around the bite becomes firm, tight, or significantly swollen.
Increasing pain — Pain that gets worse rather than better after the first day.

If you notice any of these signs, do not wait to see if it improves on its own. Skin infections from insect bites can worsen quickly.

Why Telemedicine Works Well for Infected Bites

Infected insect bites are one of the conditions best suited to telemedicine evaluation because the doctor can see the bite on video. During your visit:

You show the bite on camera so the doctor can assess redness, swelling, and drainage
The doctor compares the current appearance to your description of how it has changed
Measurements (how far redness extends) help determine severity
The doctor can see if red streaks or surrounding skin changes are present

This visual assessment, combined with your symptom history, gives the physician enough information to diagnose a skin infection and prescribe appropriate treatment without an in-person visit.

How to Get Treatment Online

Take a photo — Before your visit, photograph the bite with good lighting. If you drew a circle around the redness earlier, include that.
Start a telemedicine visit — Virtual ER is available 24/7.
Show the bite — Point your camera at the affected area. Describe when the bite occurred, how it has changed, and any symptoms.
Get treatment — Your doctor prescribes antibiotics and wound care instructions. The prescription goes to your pharmacy electronically.

Most visits take 10 to 20 minutes.

What Treatment to Expect

For Mild Infection (Cellulitis Without Abscess)

Oral antibiotics — Typically a 7-10 day course. Common choices include cephalexin, doxycycline, or trimethoprim-sulfamethoxazole depending on suspected bacteria.
Warm compresses — Applied to the area for 15-20 minutes, 3-4 times daily, to promote healing.
Elevation — If the bite is on a limb, elevating it reduces swelling.
Monitoring — Your doctor may ask you to draw a line around the redness and send a follow-up photo in 48 hours.

For Allergic Reaction to the Bite

If the swelling is from an allergic reaction rather than infection (no pus, no fever, no spreading redness), your doctor may prescribe:

Oral antihistamines (cetirizine, diphenhydramine)
Topical corticosteroid cream
Oral corticosteroids for severe reactions

When You Need In-Person Care

Your telemedicine doctor will direct you to in-person care if:

An abscess (pocket of pus) needs to be drained
The infection appears deep or involves the joint
IV antibiotics may be needed
Red streaks are extensive or you have high fever with chills
The bite is near the eye and swelling is severe

Virtual ER can refer you to our physical ER at 5306 Bellaire Blvd in Bellaire, TX for immediate in-person treatment.

Common Insect Bites That Get Infected

In the Houston and Bellaire area, these bites are most likely to become infected:

Mosquito bites — Scratching breaks the skin and introduces bacteria.
Fire ant stings — Pustules that form can rupture and become infected.
Spider bites — Brown recluse bites can cause tissue damage that becomes secondarily infected.
Flea bites — Multiple bites with heavy scratching increase infection risk.
Chigger bites — Intense itching leads to scratching and skin breaks.

The most common bacteria causing insect bite infections are Staphylococcus aureus and Streptococcus species — the same bacteria that cause most skin infections.

Preventing Insect Bite Infections

After any bite or sting:

Clean the area — Wash with soap and water immediately.
Avoid scratching — Easier said than done, but scratching is the primary way bacteria enter a bite wound. Use anti-itch cream or oral antihistamines instead.
Apply antibiotic ointment — A thin layer of over-the-counter antibiotic ointment and a bandage can help prevent infection.
Watch for changes — Check the bite daily for the first week.
Keep fingernails short — Especially for children who scratch bites in their sleep.

Frequently Asked Questions

Can I get antibiotics for an infected bug bite without going to a doctor’s office?

Yes. A Virtual ER telemedicine doctor can evaluate your infected bite on video and prescribe antibiotics sent electronically to your pharmacy. No office visit or waiting room required.

How fast does an infected insect bite spread?

A bacterial infection can spread noticeably within hours. If you see redness expanding, red streaks developing, or increasing pain and warmth, seek medical attention promptly rather than waiting to see if it improves overnight.

Should I pop a blister on a bug bite?

No. Popping blisters or pustules (such as those from fire ant stings) increases the risk of infection. Keep the area clean, apply antibiotic ointment, and cover with a bandage. If a blister ruptures on its own, clean the area and apply a fresh bandage.

When should I call 911 for an insect bite?

Call 911 if you experience signs of anaphylaxis after a bite or sting: throat swelling, difficulty breathing, rapid heartbeat, dizziness, widespread hives, or loss of consciousness. Anaphylaxis is a life-threatening emergency. A localized infected bite, while it needs medical attention, does not require 911.

Medically reviewed by Dr. Mario Quintanilla, MD — Chief Medical Director, Bellaire ER. Last reviewed: July 2026.