Allergy: Insect Stings

Insect stings occur commonly, especialty among children and during summer months.

Insect stings usually lead to itching or painful bumps and redness at the site of the sting. Fortunately they are almost always non-life-threatening unless the insect is particularly venomous, such as certain spiders, such as black widows, or scorpions.

The reaction that everyone experiences following a bite or sting is called a "toxic reaction" because the body is reacting to the venom delivered from the sting. This toxic reaction is different from an allergic reaction, which occurs less frequently and is often more serious.

A true "allergic reaction" describes an immune response to the venom in someone who is allergic to that particlar venom.

After a person is first bit or stung, he or she can develop antibodies against that insect venom called IgE antibodies. (This first sting can sometimes occur without a person knowing about it.) These IgE antibodies are trained to recognize the venom and to attack it when exposed to it in again. Another sting by the same type of insect triggers an allergic reaction by this IgE antibody and a sudden release of histamine into the tissues.

This histamine can cause a variety of allergy symptoms, ranging from severe swelling at the site of the sting or a more widespread itchy rash called hives.  In some cases, a severe allergic reaction called anaphylaxis may occur.

Are certain insect stings more likely to produce an allergic reaction?

To avoid stinging insects, it is important to learn what they look like and where they live. Most sting reactions are caused by five types of insects: yellowjackets, honeybees, paper wasps, hornets, and fire ants.

  • Yellowjackets are black with yellow markings, and are found in various climates. Their papery nests are usually located underground but are sometimes found in the building walls, masonry cracks, or woodpiles.
  • Honeybees have a rounded, fuzzy body with dark brown coloring and yellow markings. Upon stinging, the honeybee usually leaves its barbed stinger in its victim; the bee dies as a result. They are not aggressive and will only sting when provoked. However, Africanized honeybees, or so-called “killer bees” found in the southwestern United States and South and Central America, are more aggressive and may sting in swarms. Domesticated honeybees live in man-made hives, while wild honeybees live in colonies or “honeycombs” in hollow trees or building cavities. Africanized honeybees may nest in holes in house frames, between fence posts, in old tires or holes in the ground, or other partially protected sites.
  • Paper wasps' slender, elongated bodies are black, brown, or red with yellow markings. Their nests are also made of a papery material that forms a circular comb of cells which opens downward. The nests are often located under eaves, behind shutters, or in shrubs or woodpiles.
  • Hornets are black or brown with white, orange or yellow markings and are usually larger than yellowjackets. Their nests are gray or brown, football-shaped, and made of a paper material similar to that of yellowjackets' nests. Hornets' nests are usually found high above ground on branches of trees, in shrubbery, on gables, or in tree hollows.
  • Fire ants are reddish brown to black and are related to bees and wasps. They build nests of dirt in the ground that may be quite tall (18 inches) in the right kinds of soil. They may attack with little warning: after firmly grasping the victim's skin with its jaws, the fire ant arches its back as it inserts its rear stinger into the skin. It then pivots at the head and may inflict multiple stings in a circular pattern. Fire ant venom often causes an immediate burning sensation.

What are the symptoms of a severe reaction?

Most allergic reactions to insect stings aren't life-threatening, but they can be dangerous in a small number of people. One reaction, anaphylaxis, can cause a sudden drop in blood presure that affects many body organs. Symptoms of anaphylaxis include:

  • Itching and hives over large areas of the body
  • Swelling in the throat or tongue
  • Breathing difficulties
  • Dizziness
  • Stomach cramps
  • Nausea or diarrhea
  • Muscle spasms
  • Fainting

In severe cases, anaphylaxis may result in shock and loss of consciousness. This is a medical emergency and may be fatal. If you or anyone else experiences any of these symptoms after an insect sting, obtain emergency medical treatment immediately.

How are insect allergies treated?

Severe reactions

An anaphylactic reaction must be treated immediately, usually with an epinephrine (adrenalin) injection. If you are severely insect-allergic and have had prior reactions, be extra careful outdoors (or any areas where insects live) and carry an auto-injectable epinephrine device (such as an EpiPen or Twinject). Learn how to give yourself the epinephrine according to your doctor's instructions, and replace the device before the labeled expiration date.

Remember that injectable epinephrine is rescue medication only, and you must still have someone take you to an emergency room immediately if you are stung. Additional medical treatment may be necessary.

Those with severe allergies may want to wear a special bracelet or necklace that identifies the wearer as having severe allergies and displays other important medical information.

Non-severe reactions

Whether or not you have an insect allergy, you'll probably experience symptoms immediately after being stung. If the insect has left its stinger in your skin, remove it immediately to avoid receiving more venom. Try to avoid squeezing the stinger during removal—this forces more venom through the stinger and into the skin.

Usually only honeybees leave a stinger behind, rather than hornets, wasps, and yellowjackets. If there are still insects around, try to remain calm, and brush these insects from the skin promptly with deliberate movements to prevent additional stings. Then, quietly and immediately leave the area.

If you are stung by fire ants, carefully brush them off to prevent repeated stings, and leave the area. Fire ant stings usually result in the development of a blister within a day after the sting. The blister will appear to be cloudy, but it's not pustular. Fire ant venom kills bacteria, this is just dead tissue and should be left alone. It will dry and heal within a week or so, with accompanying (but not usually dangerous) swelling, itching, redness, or pain. Avoid touching or puncturing the blister, as this could cause a secondary bacterial infection.

These following steps can help in treating local reactions to insect stings:

  • Elevate the affected arm or leg and apply ice or a cold compress to reduce swelling and pain.
  • Gently clean blisters with soap and water to prevent secondary infections; do not break blisters.
  • Use topical steroid ointments or oral antihistamines to relieve itching.

If you have diabetes or another circulatory disorders (such as varicose veins or phlebitis), you may be at more risk for complications; see you health care provider to be monitored after being stung. See your doctor if swelling progresses or if the sting site seems infected.

How can insect stings be prevented?

The first and best way to prevent insect stings, of course, is to avoid the "territory" of the stinging insects' nests. If you have hives or nests around your home, have them removed, preferably by an exterminator.

If you encounter any flying stinging insects, remain calm and quiet, and move slowly away from them. Many stinging insects are looking for food, so avoid wearing scented cosmetics or brightly colored clothing that can make you a more attractive target. Because the smell of food attracts insects, be careful when cooking, eating, or drinking sweet drinks like soda or juice outdoors. Keep food covered until eaten. Wear closed-toe shoes outdoors and avoid going barefoot. Also, avoid loose-fitting garments that can trap insects between material and skin.

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© 2010 Vivacare. Last updated November 20, 2011.

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Additional Resources

Overview
Insect Sting Allergy Overview (link to Asthma & Allergy Foundation of America )
Treatment Summary
Symptom Management
Self Care
MedicAlert Foundation (Medical Bracelets) (link to MedicAlert Foundation)
En Espanol
More Information
Fire Ants (AAAAI) (link to AAAAI)
Insect Bites and Stings (link to AAP)
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