Coping With Bug Bites

Bug bites may seem like a rite of passage for enjoying the outdoors, but WebMD tells you how to protect yourself and when to take emergency action.

Medically Reviewed by Louise Chang, MD

Labor Day! Last call for the public pool, for that big, extended family barbeque - and to finally deal with an enemy that has bugged all your other summer outings.

If you've been feeling hassled by horseflies and mobbed by mosquitoes, here's how to cope with those unavoidable annoyances of the outdoors. And how to tell if that little welt is turning into something more serious.

Know Your Enemy

There are more than 170 million insects for every person on earth -- and sometimes it seems like they're all in your backyard. Feeling flea-bitten? You may never catch the culprit -- but most likely, it was one of these bothersome bugs.


These little bloodsuckers love water and damp conditions. Only the female bites, injecting saliva under the skin. The red, itchy welts from mosquito bites result from an allergic reaction to the saliva.

  • Some people become immune after many lifetime bites, while other people become more allergic to mosquito bites over time.
  • Wearing long sleeves and pants, and using insect repellant with DEET, will protect you from most bites.
  • Taking an antihistamine like Claritin before going outside can decrease your reaction to bites.
  • Rarely, mosquitoes transmit West Nile virus, which causes flu-like symptoms and encephalitis (inflammation of the brain).

Biting Flies

No-see-ums, horseflies, deerflies, blackflies, and sand flies are in this gang of pests. Their bite is more painful and annoying than mosquitoes', and can rarely cause an allergic reaction.

Black and Red Fire Ants

On the rise, they're most common in the South. They can create a small blister or pustule (pus-filled swelling) that comes a day or two after the bite. This goes away in a few days. Many people who are allergic to bees or wasps are also allergic to fire ants.

Yellow Jackets, Hornets, Wasps, and Bees

Although famed and feared for their painful stings, these striped buzzers almost never attack unless their nests are disturbed or they are antagonized.

  • Never swing or swat at them; it can provoke an attack. Don't crush or smash one either -- this can release an alarm scent that may stimulate others to sting.
  • If you're being buzzed, cover your face and stand still or walk away slowly. Don't run!

Reality Bites

Wearing long sleeves and pants, never going barefoot, and avoiding insect-infested areas and nests will prevent most bites and stings. Spend enough time outdoors, though, and one day you'll likely feel that telltale pinch. How can you tell if a bite or sting is serious?

According to Pramod Kelkar, MD, an allergist and immunologist in Maple Grove, Minn., reactions to insect bites fall into three categories:

1. Normal Reaction

When insects bite or sting, they commonly inject a small amount of venom or chemicals under the skin. This irritating beetle juice causes the reaction most of us are familiar with:

  • A small area (less than half an inch) of redness, swelling, and itching
  • Pain, especially when stinging insects are involved.

The worst of these symptoms should resolve within a few hours, and simple remedies can help ease the discomfort:

2. Large, Local Reactions

Rarely, the reaction gets worse instead of going away. A revved-up immune response to a bite or sting may lead to significant swelling and pain over a larger area of the body.

Large local reactions:

  • Can spread to involve an entire arm or leg
  • Can be severely painful and disabling
  • Often require treatment with a prescription medication, such as prednisone (an oral steroid), to fight inflammation.

Large local reactions develop slowly and usually require a trip to the family doctor, not the ER.

How do you know when it's time to get help?

  • After a few hours, the swelling is getting worse, not better
  • The swelling involves more than one-third of your arm or leg
  • Pain and swelling stop you from using that part of your body.

You can't predict if you'll get a large local reaction, but, "If you've had this reaction before, you are more likely to have it again," says Kelkar.

3. Life-Threatening Reactions (anaphylaxis)

This is the bad stuff. A small minority of people are at risk -- between 1 in 300 and 1 in 2000. Although rare, this reaction to common insect bites can be life-threatening. What is anaphylaxis?

  • An allergic reaction that spreads through the whole body
  • Itching and swelling that commonly occur far away from the bite or sting
  • Swelling that can squeeze the lung's airway closed -- a medical emergency.

What are the warning signs of anaphylaxis?

  • Itching all over your body. "Some people ignore the itching until they have difficulty breathing, which is a mistake," says Kelkar.
  • Having trouble breathing. According to Kelkar, some people won't have any itching, so this will be their first warning sign.
  • If these symptoms occur, call 911. Taking an antihistamine like Benadryl can slow the process, but urgent medical attention is essential.

How can you know if you're vulnerable to anaphylaxis? Unfortunately, you can't. But according to Kelkar, "If you've had a large local reaction, you're at slightly higher risk." Although a third of the people who get life-threatening reactions have other allergies, "the vast majority of people with allergies will never have a serious reaction to an insect bite," Kelkar points out.

Spiders and the Itsy Bitsy Bite

Most spiders are creepy, scary, and harmless -- their jaws can't even penetrate human skin. Spiders are not aggressive; in fact, they'll run any chance they get.

When spiders do bite (if surprised or trapped), they typically cause tiny wounds with minor reactions. But there are two spiders in North America that have a dangerous bite.

  • Black Widow. The female black widow is shiny, with a red hourglass marking on her belly's underside. If you think you've been bitten by a black widow spider, seek medical attention immediately. Although it is extremely poisonous, no one has died from a black widow bite in the U.S. in more than 10 years.
  • Brown Recluse. These shy spiders live only in the central and southern U.S. Their bite can cause a large, serious wound that needs medical attention. However, "The brown recluse often gets blamed for causing skin lesions in areas of North America where it doesn't exist," says Rick Vetter, an arachnologist with the University of California, Riverside.

"Usually, when we see people who think they have a spider bite, it's an unrelated skin infection," adds Rick Spurlock, an emergency room physician at Grady Memorial Hospital in Atlanta.

For a spider bite - other than one by a black widow, common sense measures are appropriate.

  • Wash the area with antiseptic soap and water, and keep it clean.
  • If the wound gets worse, or if you develop severe symptoms, see a doctor.
  • Use ice packs, over-the-counter pain relievers and antihistamines for moderate symptoms.

Show Sources

SOURCES: Michael Wells, MD, University of Arizona. Pramod Kelkar, MD, an allergist and immunologist in Maple Grove, Minn. Ohio State University, department of entomology. University of Florida, entomology and nematology department. California Poison Control System. Rick Vetter, MS, department of entomology, University of California, Riverside. Rick Spurlock, MD, department of emergency medicine, Emory University School of Medicine, Atlanta.

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