Allergic Reactions to Insect Stings

Deaths occur every year from allergic reactions to insect stings. Many could be prevented if proper precautions are taken. As a general rule, local reactions (even very large ones) to insects such as hornets, bees, and fire ants, do not require any work-up or precautions. This is because these local reactions do not imply that the patient is at significant risk for severe allergic reactions like anaphylaxis.

In adults, any immediate systemic reaction (i.e., generalized hives, angioedema, wheezing, hypotension), no matter how mild, requires consideration for skin testing and immunotherapy. The reason being is that there is a very real chance of the patient’s next sting event being more severe.

In children, urticaria alone does not often portend a more serious reaction. So, only reactions involving respiratory or hypotensive symptoms should suggest the need for skin testing and immunotherapy. An exception to this rule of thumb might be Fire Ants. Some experts are suggesting that even hives alone may be reason enough to start shots in children. The reasoning is that these stings are so common (especially in the Southeast) and the reactions to them can be severe in certain individuals.

If a patient is sensitive, venom immunotherapy is up to 95% effective in protecting against a life-threatening reaction. Of course, all patients with a history of a systemic reaction should be given an Epipen™ or similar self-injectable epinephrine preparation. Also, these patients should consider ordering a medical alert bracelet, i.e., this may be of diagnostic help in the event of an arrest due to a hymenoptera sting. They should also be instructed on insect sting avoidance

Anaphylaxis is the most severe form of allergic reaction that can occur with insect stings: causing any combination of dizziness, weakness or unconsciousness, throat tightness or difficulty breathing, itching, and hives (welts) of the skin. The reaction usually starts within minutes (rarely more than 30-60 minutes) after the sting. The same type of reaction can occur in food allergies (especially seafood and nuts) and drug reactions (penicillin and others).

“Local reactions” are those type of responses that occur at the site of the sting or in the area adjoining the sting site. These local reactions can involve quite a large, painful swollen area – however, local reactions are not of major concern, because they don’t suggest a significant risk for life-threatening reactions in the future.

Anaphylactic reactions to insects can be very severe or even life threatening, but they usually clear up in one or two hours after treatment with the right medications. Importantly, a similar or worse reaction is likely to happen again if preventative measures are not taken. This information is provided so you can understand the dangers, and know what you can do to prevent such an event.

If you’ve had an anaphylactic reaction, you are certainly not alone. Two to five million Americans have had similar reactions to insect stings and many others have had anaphylaxis to foods or medications. At least 40 deaths occur each year in the USA as a result of allergic reactions to insect stings.

What action should you take?

Talk to your doctor. This severe allergic reaction can happen again but can be prevented with the help of good medical advice. Your doctor may recommend consultation with an allergist to discuss avoidance of stings, emergency treatment and self-treatment measures, and a preventative immunization program to eliminate the danger.

Not enough is known about allergies in general to talk in terms of a “cure,” but serious anaphylactic reactions can in most cases be prevented from occurring by a treatment known as immunotherapy. This involves administering the venom in gradually increasing doses that stimulate the patient’s immune system to become more and more resistant to the allergic reaction. The dose of the venom is increased until it finally reaches the point where it is equivalent to one or two actual insect stings, and in time the patient’s immune system changes sufficiently so that it tolerates the venom normally. In a matter of weeks, patients who previously lived with the constant threat of severe reactions to insect stings can lead normal lives. Unlike most medical treatments, venom immunotherapy is close to 100% effective.

Venom immunotherapy is an effective treatment for stinging insect allergy, but its benefits and potential risks must be carefully evaluated by an allergist before a decision to treat is reached. The first step is to identify the particular venom that has produced the reaction, and this is accomplished by the combination of a careful history and a skin test with a very weak solution of the venom. Some reactions are not allergic in nature at all, and in those cases venom immunotherapy is not indicated.

Avoidance of flying insects with stingers

If you are allergic to any of the stinging insects, take steps to protect yourself from locations, situations, and clothing that attract them:
Be careful around trash cans, as sugar-containing garbage attracts flying insects.
Keep an insecticide spray that is specific for stinging insects handy at home, in your car, and when you are out of doors.
Avoid perfumes, hair sprays, suntan lotion, and other scented cosmetic products when outdoors.
Do not go barefoot or wear floppy clothing outdoors. White or subdued shades of green, tan, or khaki are preferable. Minimize the area of exposed skin when you are out of doors. Wear long sleeves, slacks, and stockings.
Be especially cautious when gardening and wear gloves. Remember that yellow jackets nest in the ground, hornets in bushes and trees. Flowers attract every species of stinging insects.
In the southeastern USA stinging fire ants live in large mounds. Avoid woodpiles and lawn mowers.
Check all window screens for openings and keep car windows closed when driving.
During the insect season, check outside your home and nearby structures for insect nests.
Avoid picnic areas, fruit orchards, beaches, and other locations that feature exposed food, fragrances, and bright colors, all of which attract stinging insects.
Never drink from a can or bottle that might have a hidden insect inside.
Tell your family and friends what type of insect you are allergic to. Inform teachers, physical education coaches, baby-sitters, camp counselors, swimming and tennis instructors of a child’s allergy.
Carry your self-injectable epinephrine device with you at all times. Instruct family members and companions how to use it. Always wear an alert bracelet.

In addition, those who are allergic to fire ants should also:

Avoid areas known to be contaminated like yards, parks, campsites, pools, golf courses, tennis courts, construction sites.
Be constantly on the lookout for ant mounds. Be careful not to step on them while walking outside.
Wear shoes and socks over the hem of pants at all times when outdoors. Long sleeves with gloves over the sleeves if you have to work in the soil. Do not lift rocks.
If you have to sit in the grass, inspect the area for ant mounds and sit only for the minimum time necessary. Do not fall asleep in the grass.
Be careful when stepping down from a car on the grass.
Do not perform gardening, yard work, or construction. Be careful with air conditioning units.
Treat the yard around your home (treatment of the neighbor’s yards could be suggested). Inquire if schools, campsites, tennis courts, pools, and other such areas have been treated for fire ants.
Two approaches to the control of fire ants are currently in use:
Treatment of individual mounds. Drenching individual mounds with diazinon or injecting mounds with chlorpyrifos under pressure. These measures may temporarily clear small areas, but are soon reinfested from surrounding areas.
Modern broadcast treatment. Use attractant baits consisting of soybean oil, corn grits, and chemical agents. The bait is picked up by the worker ants and taken deep into the mound to the queen. When used appropriately, these agents appear to be capable of clearing large areas of ants for months at a time.

Seasons of concern

The season during which various insects are most active depend on the insect and geographic area, but in northern and temperate regions there is no appreciable insect presence during the winter, and such precautions are less necessary. Summer would be the season to take extra precautions in those areas. In milder climates such as Southern Florida, the risk of exposure could be year round, and so the kit should always be available.

What to do if you get stung

If you are stung, do what your doctor has instructed you.

Stay calm and plan to get medical attention for observation. Also get in touch with someone immediately if you are alone.
If the reaction is serious enough, most doctors would recommend immediately using a self-treatment kit for the injection of epinephrine (Epipen™, for example). This is extremely effective in slowing or stopping the reaction in most cases, but it is not always enough.
If such a self injectable epinephrine kit is used, it should be while the person is on the way to receiving emergency medical care. It should not replace medical evaluation.
Immediately apply a tourniquet between the sting and the rest of your body if possible. Remove the tourniquet every 15 minutes to allow blood flow to and from that body part.
Apply an ice bag or cold compresses to the sting site to slow absorption of the venom.
If the reaction is severe, you should call 911.
If the reaction is less than severe, you should still go to the emergency room where a doctor can observe you for several hours until the danger has passed. In many cases other treatment (oxygen, intravenous fluids) is important.
The emergency room physician may give you some oral Prednisone or injectable cortisone initially, and he may continue the prednisone for the next 24 hours.

Preventative immunization (immunotherapy or “allergy shots“) is often recommended strongly. This treatment program virtually eliminates any danger of a sting reaction. It is also prudent to carry on your person a card, or some other means of identifying yourself as a person hypersensitive to insect stings. It is unfortunately possible for you to be stung while you’re alone and for a reaction to overcome you before help arrives. Your condition could easily be mistaken for any number of other things.