Stinging insect allergy

Each year, many Americans are stung by insects. For most of those unfortunate enough to be stung, these stings mean pain and discomfort generally lasting only a few hours. Symptoms may include redness, swelling and itching at the site of the sting.

However, some people are allergic to insect stings. This means that their immune systems overreact to the venom injected by a stinging insect. After the first sting, the allergic person’s body produces an allergic substance called Immunoglobulin E (IgE) antibody , which reacts with the insect venom. The individual does not usually experience a severe allergic reaction from that first stingbut if he or she is stung again by an insect of the same or similar species, the insect venom interacts with the IgE antibody produced in response to the earlier sting. This triggers the release of histamine and other chemicals that cause allergic symptoms.  

  • Symptoms of severe reactions

For a small number of people with severe venom allergy, stings may be life-threatening. Severe allergic reactions to insect stings can involve many body organs and may develop rapidly. This reaction is called anaphylaxis . Symptoms of anaphylaxis may include itching and hives over large areas of the body, swelling in the throat or tongue, difficulty breathing, dizziness, stomach cramps, nausea or diarrhea. In severe cases, a rapid fall in blood pressure may result in shock and loss of consciousness. Anaphylaxis 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. After your symptoms are treated in the emergency room, you should also obtain referral to an allergist to learn about treatment options.

  • Identifying stinging insects

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

Yellow jackets are black with yellow markings, and are found in various climates. Their nests, which are made of a papier-maché material, are usually located underground, but can sometimes be found in the walls of frame buildings, cracks in masonry 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. Honeybees are nonaggressive 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 cavities of buildings. 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 paper-like 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 yellow jackets. Their nests are gray or brown, football-shaped, and made of a paper material similar to that of yellow jackets nests. Hornetsnests are usually found high above ground on branches of trees, in shrubbery, on gables or in tree hollows.

Fire ants are reddish brown stinging insects related to bees and wasps. Their prominent mounds, common in warmer climates, may measure up to three feet in diameter and 18 inches in height, and can contain up to 250,000 ants. Fire ants may attack with little warning: after firmly grasping the victim 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 typically inflicts about eight stings in a circular pattern. Fire ant venom has a high concentration of toxins, which cause burning pain.

  • Preventing stings

Stay out of the “territory” of the stinging insects’ nests. These insects are “social” and will sting if their homes are disturbed, so it is important to have hives and nests around your home destroyed. Since this activity can be dangerous, a trained exterminator should be hired.

If you encounter any flying stinging insects, remain calm and quiet, and move slowly. Many stinging insects are searching for nectar, so don’t look or smell like a flower avoid brightly colored clothing and perfume when outdoors. 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.

  • Treating stings

If you are stung by a honeybee that has left its stinger (and attached venom sac) in your skin, remove the stinger within 30 seconds to avoid receiving more venom. A quick scrape of a fingernail removes the stinger and sac. Avoid squeezing the saca this forces more venom through the stinger and into the skin. Hornets, wasps, and yellow jackets do not usually leave their stingers. 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 cause a reaction in almost all their victims. An itchy, localized hive at the sting site forms and then usually subsides within 30 to 60 minutes. Within four hours, a small blister forms at the site of each sting; a sterile sore with pus forms in eight to 24 hours. This sore then ruptures and scars in 48 to 72 hours. Stings must be monitored for secondary bacterial infection. Diabetics and others with circulatory disorders, including varicose veins and phlebitis, can be particularly at risk for complications, and should see a physician to monitor their condition after being stung. Up to 50% of patients develop large local reactions at the site of fire ant stings swelling may last for several days and may be accompanied by itching, redness and pain.

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

  1. Elevate the affected arm or leg and apply ice or a cold compress to reduce swelling and pain.
  2. Gently clean blisters with soap and water to prevent secondary infections; do not break blisters.
  3. Use topical steroid ointments or oral antihistamines to relieve itching.
  4. See your doctor if swelling progresses or if the sting site seems infected.

If you are severely insect-allergic and have had prior reactions, try to avoid being outdoors alone in insect weather in case you require prompt emergency treatment. Carry an auto-injectable epinephrine (adrenalin) device, a short-term treatment for severe allergic reactions. Learn how to self-administer the epinephrine according to your allergist’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 consider wearing a special bracelet or necklace that identifies the wearer as having severe allergies and supplies other important medical information.

  • Consulting your allergist

Anyone who has had a serious adverse reaction to an insect sting should be evaluated by an allergist, who will take a thorough history, perform an examination and recommend testing to determine whether you have an allergy, and which type of stinging insect caused the reaction. Skin or blood (RAST) testing for insect allergy is used to detect the presence of significant amounts of IgE antibody.

Your allergist will help you determine the best form of treatment. Those who have severe allergies to insect venom should consider receiving insect venom immunotherapy, a highly effective vaccination program that actually prevents future allergic sting reactions in 97% of treated patients. During immunotherapy, the allergist administers gradually stronger doses of venom extract every few weeks over a period of three to five years. This helps the patient’s immune system to become more and more resistant to future insect stings.

If you have questions about venom immunotherapy or other treatments for stinging insect allergy, be sure to ask your allergist. Patients who receive appropriate treatment such as immunotherapy and who practice careful avoidance measures can participate in regular outdoor activities.