Steven Machtinger, MD

Anaphylaxis to Insect Stings

Aren't most people allergic to bee and wasp stings?

Serious allergic reactions to the stings of insects of the family Hymenoptera are common occurring in up to 3% of adults and 1% of children. Members of this large family of insects include honeybees, yellow jackets, wasps, hornets, and fire ants. When these insects sting they inject venom under the skin of the victim that causes redness, heat, swelling, itching, and pain. These symptoms of inflammation resemble those of an allergic reaction.

What's the difference between allergic and non-allergic reactions to stings from these insects?

Persons allergic to the venom of these insects experience an anaphylactic reaction when stung. Anaphylaxis is a potentially life-threatening allergic reaction of rapid onset. In the United States, about 40 to 50 deaths are attributed to the stings of these insects annually.

How are anaphylactic reactions different from other allergic reactions?

The difference between anaphylaxis and less serious allergic reactions is the magnitude of the reaction, the simultaneous involvement of several organ systems, and the effects on the windpipe and blood circulation. strong> Typical skin symptoms of anaphylaxis include itching, hives, and swelling of the hands, feet, lips, and eyelids called angioedema. Common digestive symptoms including nausea, vomiting, diarrhea, and abdominal pain are similar to those seen in food allergies. Nasal congestion and runny nose, symptoms of allergic rhinitis, and wheezing and chest pain, symptoms of asthma, may also occur in anaphylaxis. More serious allergy symptoms include partial or complete blockage of the windpipe (trachea) due to swelling and shock due to low blood pressure or even direct heart dysfunction.

When I'm stung on the hand by a yellow jacket my entire arm swells up. Am I allergic?

A large local reaction of type is not predictive of anaphylaxis on subsequent stings.

My brother has anaphylaxis to bee stings. Are there any tests that can predict if I will develop a similar problem?

No. No. Neither skin tests nor blood tests can predict whether you will develop an allergic reaction to the venom of the sting of a member of the family Hymenoptera.

How will I know if I'm having an anaphylactic reaction to a sting?

Within a few seconds or minutes you will probably notice your skin itching and difficulty breathing due to a constriction in your throat. You may feel dizzy, apprehensive, and nauseous. Symptoms can progress very rapidly. It is common to become anxious.

Can I have an anaphylactic reaction the first time I'm stung?

No. You must be stung at least once in the past in order for your immune system to produce the special type of antibody that triggers anaphylaxis on subsequent stings.

If I think I'm having an anaphylactic reaction what should I do?

Try to stay calm. If you have an antihistamine, take it. If the stinger is still in your skin, try to flick it off. Don't grasp the stinger between your fingers as this may squeeze additional venom into you. Put some ice on the sting site. Go immediately to the nearest emergency department or urgent care center. Have someone else drive.

They told me in the Emergency Room that I'm allergic to bee stings. Now what?

You need to see an allergist experienced in evaluation of venom allergy. The diagnosis will depend on the details of your reaction to the sting or stings and the results of skin testing to venom.

Will I always be tested for venom allergy when I see the allergist?

You should be tested for allergy to venom if:

You had hives after a sting.
You had difficulty breathing after a sting.
You had symptoms of anaphylaxis after a sting.

What if the results of the evaluation are positive?

You have an allergy to the venom of one or more species of the class Hymenoptera. You should take the following steps to prevent future life-threatening reactions to stings:

Learn to use an EpiPen® (or EpiPen, Jr. ® for children under sixty pounds) injectable adrenaline device.
Always have at least one such device with you at all times.
Use the device immediately if you are stung, even if you feel fine.
Go to the nearest Emergency Department immediately after any sting even if you received adrenaline.
Begin immunotherapy to the venom(s) to which you are allergic.
Wear a Medi-Alert bracelet or necklace indicating your extreme allergy to venom stings.
Don't wear perfume, cologne, after shave, or brightly colored clothing when outdoors.
Inform family members, friends, coworkers, teachers, and daycare attendants of your problem.

What if the results of the evaluation are negative?

It's our policy to double check for venom allergy through blood testing (CAP-RAST) when the history is positive and skin tests are negative.

If I'm allergic to yellow jackets will I also be allergic to honey bees?

Not necessarily. There is considerable cross-reactivity between the allergenic components of each species' venom so that many but not all allergic persons will be sensitized to several different species. This question is resolved through skin testing.

Why must I use adrenaline?

Epinephrine (also called adrenaline) can save your life if you are allergic to venom and receive a sting. No medication works as fast or as effectively as epinephrine. It slows, stops, or reverses swelling of the throat, falling blood pressure and heart dysfunction, asthma, and urticaria. Its effectiveness increases the sooner it is injected after a sting.

If I use epinephrine must I still go to Emergency Department?

Absolutely! The effects of epinephrine last for only fifteen to twenty minutes. Anaphylactic reactions may continue for several hours or even for a few days. The primary role of adrenaline is to keep you alive until you reach the Emergency Department.

Why should I receive venom immunotherapy if I always carry epinephrine and take other precautions to avoid stings?

In 98-99% of patients a series of venom injections provides complete protection against anaphylaxis reactions from future venom stings. Adrenaline administration is an emergency measure. Circumstances may prevent the timely administration of adrenaline or you may be far from an Emergency Department when stung. What if you're out hiking in the woods when the sting occurs? What if you forgot your EpiPen at home?

Can children with anaphylaxis to venom receive immunotherapy?

Yes. For technical reasons we usually do not give allergy injections to children under the age of six years.

Are there persons allergic to venom who should not receive venom immunotherapy?

Persons taking beta-blockers such as propranolol or atenolol should not receive immunotherapy because these drugs blunt the response to epinephrine. This means that if stung by a bee, wasp, or yellow jacket, they may have a poor response to emergency treatment. If possible, such patients should be switched to alternative medication to permit testing for venom allergy and, if necessary, venom immunotherapy. This problem should be worked out between the patient's internist or cardiologist and allergist.

How long will it take before I'm fully protected?

Using a method called modified rush immunotherapy, most venom allergic patients can be fully protected from anaphylactic reactions to venom within four months.

How often will I require venom immunotherapy injections?

You will receive approximately three months of weekly injections followed by monthly injections.

How long will I remain on venom immunotherapy?

You'll receive venom injections for at least five years. There is continuing discussion as to whether persons with allergy to insect venom should remain on monthly injections for life or stop after five years. This is a question you should discuss with your allergist in light of any new research results available at that time.

Is anaphylaxis the only serious consequence from insect stings?

Yellow jackets are attracted to garbage. Their stingers may carry bacteria that may cause localized skin or even systemic bacterial infections. The venom of honey bees often induce a flu-like syndrome of fever, fatigue, and muscle and joint pains that begins one to two days after the sting and may last for a week or so.

What about killer bees?

The venom of all bees, yellow jackets, hornets, wasps, and fire ants is a potent poison. The combined venom from twenty-five to one hundred stings received simultaneously may be lethal depending upon the age, size, and general health of the victim. Killer bees are noted not for having more potent venom but for their aggressive behavior and their tendency to swarm and sting victims many times after seemingly minor provocation.

What about allergic reactions to mosquito and spider bites?

These bites do not cause anaphylaxis. The risk of immunotherapy exceeds the risk of local allergic reactions after being bitten and is consequently not recommended.

Links to venom allergy sites:

AAAAI Patient/Public Resource Center - Tip 30: Stinging Insect Allergy
AAAAI Patient/Public Resource Center - Propina 30: Alergias A Insectos Picadores (En Espanol)
Insect Stings

CAUTION

The information above represents the writer's opinions and is not meant as a substitute for evaluation by a physician. The reader is advised to seek sound medical evaluation and guidance before undertaking treatment for any medical condition.

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