MSD Manual

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Quick Facts

Insect Bites

By

The Manual's Editorial Staff

Last full review/revision Jul 2021| Content last modified Jul 2021
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Many different types of insects (bugs) can bite you. Most insect bites itch, but the bites themselves aren't serious. The main problem with insect bites is that:

Common biting insects in the United States are:

  • Flies, including sand, horse, deer, black, and stable flies

  • Mosquitoes

  • Fleas

  • Lice

  • Bedbugs

  • Kissing bugs

  • Some water bugs

None of these insects has venom (poison).

What are the symptoms of an insect bite?

Most bites result in:

  • A small, red, itchy bump

Sometimes, you might have:

  • A large sore (ulcer) that is swollen and painful

  • Symptoms of infection, such as redness and swelling around the bite

  • Very rarely, symptoms of an allergic reaction, such as a rash, hives, or trouble breathing

Fleas can sometimes cause an allergic reaction even if you're not bitten.

What diseases are spread by insect bites?

Different types of insects spread different diseases. Not every insect carries disease, even in areas where many insects do.

Some of the diseases spread through insect bites are:

How are insect bites treated?

If you think you're having an allergic reaction, go to the hospital right away. If you know you're allergic, you should always carry epinephrine (medicine to treat a serious allergic reaction) with you. You inject the epinephrine into your own skin through a thin needle, or someone does it for you.

Doctors will tell you to:

  • Clean the bite

  • Apply a medicated cream to the bite to lessen your pain, itching, and swelling

  • Take an antihistamine medicine (such as diphenhydramine) if you have many bites

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