Venom Hypersensitivity

What is venom hypersensitivity?

Approximately 10% of the population will develop an allergic reaction to venom released by a stinging insect.  The reaction can range from a mild localized reaction to a life-threatening reaction called anaphylaxis.  Anaphylaxis is a severe allergic reaction that occurs when the body responds in an extreme manner to the venom.  Symptoms include: difficulty breathing; development of hives; swelling of the lips, tongue, or throat; gastrointestinal symptoms such vomiting; light-headedness; and even loss of consciousness.  Anaphylaxis is an emergency and can lead to death if not treated promptly.

Another common outcome from an insect sting is a local reaction.  Local reactions are areas of itching, redness, discomfort, and swelling adjacent to the sting sites.  These reactions can enlarge over 48 hours and may resemble an infection.  However, the majority of insect stings are sterile.

Which stinging insects cause major allergic reactions?

The most common stinging insects in Southern California are honey bees, paper wasps, white-faced hornets, and yellow jackets.  These stinging insects are particularly important because immunotherapy or “allergy shots” are available.  Immunotherapy reduces the risk of anaphylaxis if the person is stung again in the future.

Immunotherapy is not available for mosquito bites or bumble bee stings.  In the southern United States, fire ants are a common cause of venom allergy, and immunotherapy is available to treat this allergy as well.

Testing to venom allergies

Skin testing, laboratory testing, or both are recommended for anyone who has had an anaphylactic reaction or a large local reaction to an insect sting.  Once the culprit is identified, allergy injections or immunotherapy should be initiated as it is considered a life-saving therapy.

Treatment

All patients who have had anaphylaxis to stinging insects should carry epinephrine in the form an auto-injector.  Epinephrine is a life-saving medication that temporarily counteracts the effects of anaphylaxis.  If an auto-injector is used, emergency personnel (911) or transport to a local emergency department is required.

Immunotherapy is recommended for anyone who had anaphylaxis due to an insect sting.  Others with large local reactions may also benefit from immunotherapy, but this depends on their occupation (e.g. beekeepers, construction workers) and other related factors.  The goal of immunotherapy is to reduce the risk of anaphylaxis from a subsequent sting.