Insect Bites

  • Itching, pain, or swelling from an insect bite
  • Itchy Insect Bites: Bites of mosquitoes, chiggers (harvest mites), fleas, and bedbugs usually cause itchy, red bumps
  • Painful Insect Bites: Bites of horseflies, black flies, deer flies, gnats, harvester ants, blister beetles, and centipedes usually cause a painful, red bump. Within a few hours, fire ant bites can change to blisters or pimples


  • Tetanus vaccination after an insect bite is not necessary.


  • No-see-ums are tiny bugs that are about 1/10 - 1/15 of an inch (0.16 -0.25 cm). They can pass easily through screens. They are attracted to light. They are most active at sunset.
  • Other Names:They are also called biting midges, punkies, or sand flies.
  • Habitat: Adults live in wet sand. They are especially common along the seashore and shores of rivers and lakes. They lay their eggs near standing water (margins of ponds, ditches, lakes, muddy edges of a salt marsh).
  • Symptoms: The initial bite is generally painless. But within 12 hours the bite mark becomes a small red spot that is intensely itchy. Some sensitive people can develop a larger reaction with a swollen itchy spot (hive) 1-2 inches in diameter (2-5 cm). Scratching makes the itching last longer.
  • OTC Treatment for Itching: Topical hydrocortisone may help; anthistamines reduce the itching.
  • Prevention: No-see-ums cannot bite through clothing, thus good advice is to wear long pants and long-sleeved shirts. Insect repellents containing DEET also seem to be effective in preventing bites.


  • Common chiggers are very tiny bugs that are about 1/150 of an inch (0.017 cm) in size.
  • Other names: They are also called harvest mites, red mites, jiggers, or redbugs. They can easily go through screens.
  • Habitat: Tall grass, berry patches, edge of woods.
  • Symptoms: The main symptom is intense itching and this peaks on day 2. There are usually tiny red bumps or small hives. Tiny bumps may last for 1-2 weeks.
  • OTC Treatment: Topical hydrocortisone may help; anthistamines reduce the itching.
  • Prevention: Avoid areas where chiggers are known to be. Insect repellents containing DEET also seem to be effective in preventing bites.

Bed Bugs

  • Common Bed bugs are small visible blood-sucking bugs that are about 1/4 an inch (7 mm) in length.
  • Habitat: During the day bed bugs hide in the corners of mattresses, bed crevices, floors, and walls. At night the bed bugs come out of hiding and feed on their preferred host, humans. The common bed bug is found worldwide.
  • Symptoms: There is no pain while the bed bug is biting. However, later small red bumps or large itchy wheals (2-20 cm) may develop at the bite site. Occasionally blisters (bulla) can occur at the bite site.
  • OTC Treatment: Topical hydrocortisone cream and oral anthistamines help reduce the itching. Watch for signs of infection.
  • Prevention: Avoid hotels and hostels where bed bugs have been reported. Check along corners of bedding or mattresses for the presence of these bugs. Wash linens once a week in hot water. DEET and permethrin are effective against bed bugs.

If not, see these topics

  • RASH - LOCALIZED AND CAUSE UNKNOWN, if it does not seem like an insect bite


First Aid:

FIRST AID ADVICE for Anaphylaxis - Epinephrine (pending EMS arrival):

  • If the patient has an epinephrine autoinjector, the patient should use it now.
  • Use the autoinjector on the upper outer thigh. You may give it through clothing if necessary.

Epinephrine is available in autoinjectors under trade names: Epi-Pen, Epi-Pen Jr, and Twinject. Epi-Pen is a single injection. Twinject has a second injection that can be used if there is no improvement after 5 minutes.

FIRST AID ADVICE for Anaphylaxis - Benadryl (pending EMS arrival):

  • Give antihistamine orally NOW if able to swallow.
  • Use Benadryl (diphenhydramine; adult dose 50 mg) or any other available antihistamine.

FIRST AID ADVICE for Anaphylactic Shock (pending EMS arrival):

  • Lie down with feet elevated.
See All Treatments

Treatments for Insect Bites

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Symptoms and Screenings for Insect Bites

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Causes and Preventions for Insect Bites

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Education and Resources for Insect Bites

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Support groups for Insect Bites

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Learn More about Insect Bites

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