Stinging Insects

Insect venom allergies are common , especially allergies to members of the Hymenoptera order of insects .

While a normal response to an insect sting may consist of reddening and some pain, an anaphylactic response is much more serious and can involve changes in breathing and loss of consciousness.

Usually once you have experienced an allergic response you are likely to experience a subsequent response when exposed to the insect culprit, but the severity of the response can vary. If you, or someone you know, has an insect venom allergy then you should learn how to prevent and treat insect stings.

You may also be interested to learn more about insect sting allergies, including information on common insect culprits and what to do if someone is stung.

Incidence

It is estimated that 0.5% to 5% of the population of the United States, or as many as 13 million people, have insect venom allergies.^1,2 Many of these venom-sensitive individuals are at risk for life-threatening anaphylactic reactions. An estimated 40 to 100 deaths due to anaphylaxis caused by insect venom are reported each year, half of which are attributed to fire ants , an increasingly common pest that is spreading throughout the United States. from the south.^2-5

Common Culprits

The insects most commonly associated with triggering severe allergic reactions belong to the Hymenoptera order of insects. This order is comprised of:

• Bees
• Wasps
• Yellow jackets
• Hornets
• Ants, especially the fire ant

You may wish to learn more about stinging insects , including how to recognize and avoid them and what to do if you are stung.

Normal Response Versus Anaphylaxis

A normal response to an insect sting results in swelling, pain, and redness around the site of the sting or bite. When a person is allergic to an insect sting, he or she is susceptible to the effects of anaphylaxis, which can include:

• Itching and hives over much of the body
• Swelling in the throat or tongue
• Difficulty breathing or swallowing
• Dizziness, severe headache
• Stomach cramps, nausea, or diarrhea
• Rapid fall in blood pressure
• Shock and loss of consciousness

It is important to remember that these symptoms can progress to deadly anaphylaxis in 1 to 2 minutes,⁶ so treatment should be administered immediately.

Severity of Subsequent Allergic Reactions

In general, people who have experienced an allergic reaction from an insect sting have approximately a 30% to 60% chance of experiencing a similar or worse reaction the next time they are stung.⁷ An individual's chance of experiencing subsequent life-threatening allergic reactions varies, depending on factors such as:

• Patient age⁸
• Health⁸
• Amount of venom to which a person is exposed when stung⁸
• Severity of the initial reaction⁸

It has been shown, for example, that severe initial reactions increase the likelihood of future anaphylactic responses.

On the other hand, some people who have experienced allergic reactions to insect stings will see the severity of their reactions decrease over time or even cease spontaneously.⁹

Protection, Prevention, and Treatment

As with other anaphylactics, the primary method of protection is a two-step process: avoiding contact with what causes reactions and being prepared to treat anaphylactic emergencies by carrying self-injectable epinephrine and receiving prompt medical attention.

Unlike people susceptible to anaphylaxis triggered by food , latex , or medication allergies, people allergic to insect venom have the option of undergoing immunotherapy , a preventive course of treatment that provides long-term protection against insect sting allergies.

Avoidance

• Avoiding brightly colored clothing or sweet-smelling cosmetics and shampoos
• Keeping food and garbage covered
• Wearing shoes to guard against stepping on insects
• Keeping arms and legs covered during activities (such as gardening or hiking) that may expose you to stinging insects
• Refraining from swatting or crushing insects
• Steering clear of areas where insects have nested

Immunotherapy

If you or your child suffers from severe allergic reactions to insect stings then you should discuss the option of receiving venom immunotherapy (VIT) from your doctor, preferably a board-certified allergist.

During VIT, patients undergo a series of injections that exposes them to minute amounts of pure venom. The dosage is slightly increased over the course of the therapy, helping the patient build a tolerance to the venom proteins that trigger allergic reactions. VIT is 97% successful in preventing future allergic reactions to insect stings and is usually completed after 3 to 5 years of regular injections.^10,11

Even after patients receive VIT, however, they may be advised to carry self-injectable epinephrine because not all patients will remain tolerant to insect venom for life.¹² Moreover, VIT itself poses a 6% risk of anaphylaxis due to the venom used in the therapy. Patients should make sure that the physician who administers their VIT regimen is properly trained in immunotherapy and keeps epinephrine and other resuscitative medications and equipment needed to treat anaphylaxis on hand.

You can find a board-certified allergist by using our handy Find an Allergist feature.

Emergency Treatment

Because not all stings can be avoided, the American Academy of Allergy, Asthma and Immunology recommends that people allergic to insect stings be prepared to administer injectable epinephrine to themselves immediately if they are stung.¹³ People with insect sting allergies should carry a self-injectable form of epinephrine, such as the EpiPen^® or EpiPen^® Jr auto-injector, with them at all times. Epinephrine (also known as adrenaline) works rapidly to reverse the symptoms of anaphylaxis by relaxing smooth muscle tissue in the lungs, speeding up the heart rate, combating hives and welts on the skin, and by reducing the swelling of the mouth, throat, and face.

Side effects of epinephrine may include palpitations, tachycardia (an abnormally fast heartbeat), sweating, nausea and vomiting, and respiratory difficulty. Cardiac arrhythmias may follow administration of epinephrine. Patients should ask their physician about the circumstances under which this life-saving medication should be used.

Many physicians also recommend taking antihistamines such as diphenhydramine to relieve the symptoms of allergic reactions. However, antihistamines are not substitute for epinephrine, and only epinephrine can stop the potentially deadly effects of anaphylaxis.

Even after administering epinephrine, emergency medical treatment should be sought at once because severely allergic people experiencing anaphylaxis may need emergency respiratory or cardiac care, or even to be resuscitated if they stop breathing altogether. More commonly, these patients will need professional care to determine whether additional epinephrine, steroids, antihistamines, or other treatments are required.

Either way, follow-up diagnosis and care by medical professionals after self-administration of epinephrine for insect stings are critical to recovery.

Delayed or secondary reactions do occur, and patients should remain under medical supervision for at least 4 hours after an episode of anaphylaxis.¹⁴

Finally, because stinging insects are difficult to avoid completely, patients who have been treated for an anaphylactic reaction should protect themselves against further episodes by requesting a prescription for self-injectable epinephrine from the emergency room physician and carrying the epinephrine with them at all times, particularly when outdoors.

Patients should also ask their physicians whether antihistamines should be carried in addition to epinephrine.

Wearing a medical identification bracelet describing your allergies and susceptibility to anaphylaxis can help ensure prompt, proper treatment during an emergency.

References

1. Golden BK, Marsh DG, Kagey-Sobotka A, et al. Epidemiology of insect venom hypersensitivity. JAMA. 1989;262:240-244.
    
2. Valentine MD. Anaphylaxis and stinging insect hypersensitivity. JAMA. 1992;268:2830-2833.
    
3. AAAAI. Anaphylaxis in schools and other child-care settings. Position statement #34. J Allergy Clin Immunol. 1998;102:173-176.
    
4. Lieberman P. Preventing fatalities from anaphylaxis: an allergist-immunologist's perspective. Allergy Proc. 1995;3:109-111.
    
5. Wyatt R. Anaphylaxis: how to recognize, treat and prevent potentially fatal attacks. Postgrad Med. 1996;100:87-99.
    
6. The Merck Manual. 16th ed. Merck Research Laboratories. 1992:331.
    
7. Reisman RE. Natural history of insect sting allergy: relationship of severity of symptomatic initial sting anaphylaxis to re-sting reactions. J Allergy Clin Immunol. 1992;30:335-339.
    
8. Graft DF, et al. Position statement on the discontinuation of hymenoptera venom immunotherapy. AAAAI position statement #33. Available at: http://www.aaaai.org.
    
9. Savliwala MN, Reisman RE. Studies of the natural history of stinging-insect allergy: long-term follow-up of patients without immunotherapy. J Allergy Clin Immunol. 1987;80:741-745.
    
10. Anaphylaxis. J Allergy Clin Immunol. 1998;101:S465-S528.
     
11. Hunt KJ, Valentine MD, Kagey-Sobotka A, et al. A controlled trial of immunotherapy in insect sting hypersensitivity. N Engl J Med. 1978;299:157-161.
     
12. Graft DF, et al. Position statement on the discontinuation of hymenoptera venom immunotherapy. AAAAI position statement #33. Available at: http://www.aaaai.org.
     
13. AAAAI. The use of epinephrine in the treatment of anaphylaxis. Position statement #26. Available at: http://www.aaaai.org.
     
14. Wood RA. Anaphylaxis in children. Patient Care. 1997;31(13):161.