Stinging Insect Allergies

The first reports of stinging insect allergy came from the Middle East thousands of years ago.  Even at that time, people understood that a small insect, such as a bee or a wasp, had the potential to cause serious illness or even death. Today, physicians, and in particular allergy specialists, are equipped to diagnose and protect individuals with stinging insect allergies.The most common insects to cause stinging insect allergies are wasps, hornets, yellow jackets, and honey bees. Fire ants also cause allergic reactions, but they are classified as a biting insect and not a stinging insect. 

Classification of Reactions to Stinging Insects

The initial stage of a stinging insect allergy reaction occurs immediately after the venom of a stinging insect is introduced through the skin, causing local tissue damage and the release of histamine and other chemicals.  The resulting tissue damage is largely responsible for the pain, swelling, redness, and itching that we experience at the site of a sting. Although most local reactions are mild and cause swelling and inflammation localized around the sting site, the area of swelling and inflammation can be quite large. For example, one may be stung on the finger, yet the swelling may progress to include the entire arm. Both of these reactions, by virtue of the fact that they are contiguous with the sting site, are considered local allergic reactions.

The most severe type of insect sting allergic reaction is called a systemic or anaphylactic reaction.  This reaction occurs in individuals who have had prior stings by similar insects and have become sensitized to the stinging insect venom.  The sensitization stimulates the immune system to develop allergic antibodies (IgE) that circulate and bind the venom protein upon future stings.  The binding of IgE to the venom protein can trigger a severe anaphylactic reaction consisting of hives, throat closing, wheezing, difficulty breathing, a drop in blood pressure (shock), and possibly death.  Such reactions require emergency treatment and a delay in treatment can be catastrophic. 

Diagnosis of Stinging Insect Allergy

An allergist will likely identify the insect responsible for stinging insect allergy with specialized allergy testing. This type of testing is generally reserved for individuals who have had a previous systemic reaction.  Allergists perform skin testing to common stinging insects including honey bees, wasps, hornets and yellow jackets. Imported fire ants can also cause an anaphylactic reaction and testing is also available for this insect.

Based on the test results, your allergy specialist will determine the risk for future reactions and whether immunotherapy, or desensitization therapy, is indicated.  Unfortunately, many patients never have their allergic reactions evaluated by an allergist, thus placing them at risk for severe reactions with subsequent stings.

Treatment of Stinging Insect Allergies

Upon being stung, one should check whether the stinger is still in the skin. Interestingly, only the honey bee leaves its stinger due to its barbed configuration. If the stinger is present, it should be removed immediately. One should avoid squeezing the venom sac as this may introduce more venom into the skin. Rather, it should be scraped off of the skin with a finger nail, a credit card, or another sharp object. Ice should then be placed on the sting site, and a rapid acting antihistamine, such as diphenhydramine (Benadryl) should be administered.  Minor local reactions should resolve spontaneously, although the swelling and inflammation may persist for several days.

Systemic reactions require immediate and intensive treatment.  If a patient has any signs of a systemic reaction, such as generalized hives, redness of the skin or a sense of heat, difficulty swallowing or the sensation of the throat closing, tightness in the chest, or light-headedness, then emergency medical help should be called (911) immediately. If available, self-injectable epinephrine (Epipen) should be administered without delay.  The sooner the Epipen is injected, the more effective it will be in stopping the allergic reaction. If the reaction is persistent, the dose may need to be repeated.  Antihistamines should also be given immediately.  In addition, steroids may be needed to prevent a late or delayed reaction after the initial systemic reaction. The most important concept to remember about a systemic reaction to an insect sting is to not delay treatment. A systemic stinging insect allergic reaction is a true and serious allergic emergency and should be treated accordingly. 

Stinging Insect Allergy Follow-up

It is also critical that one follow up with an allergist after a systemic reaction.  Your allergist will prescribe an auto-injector containing epinephrine or adrenaline (EpiPen or EpiPen Jr) which should accompany one at all times. These devices allow one to self-inject if they should be stung again and exhibit symptoms suggesting an impending systemic reaction.

Any person who has had a systemic reaction to a stinging or biting insect should be referred to an allergy specialist.  Allergists have been trained to treat insect sting allergies using a desensitization procedure called venom immunotherapy.  Venom immunotherapy works by introducing small amounts of the insect venom that caused the patient’s reaction in order for the immune system to develop a tolerance to future stings.  It is extremely effective for most insect sting allergies such as bees, hornets, wasps or fire ants, and is highly effective in preventing future systemic reactions.  The treatment is considered safe and works relatively quickly.  Any individual who has had a systemic reaction should ask his or her physician for a referral to an allergist in order to determine whether venom immunotherapy is appropriate. 

Stinging Insect Precautions

General precautions for insect allergic individuals include:

  • Not walking barefoot outside
  • Not wearing bright colored clothing that could attract insects
  • Not drinking sugary beverages outside which also may attract stinging insects
  • Avoid areas where insects tend to frequent such as flower gardens and picnic areas

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