When you are stung by an insect, poisons and other toxins enter your skin. It is normal to have some swelling, redness, pain, and itching around the sting. But you may have an allergic reaction if your immune system reacts strongly to allergens in the sting.
You probably will not have a severe allergic reaction the first time you are stung. But even if your first reaction to a sting is mild, allergic reactions can get worse with each sting. Your next reaction may be more severe or even deadly.
An allergic reaction occurs when your immune system reacts strongly to the allergens in the sting.
A few types of stinging insects cause most allergic reactions. They are:
Symptoms of an allergic reaction can range from mild to severe. Mild allergic reactions cause:
A more serious allergic reaction can spread to your whole body. This kind of reaction can cause:
A deadly allergic reaction, called anaphylaxis (say “ann-uh-fuh-LAK-suss”), can cause:
Your doctor may do a physical examination and ask you questions about your symptoms and past health. He or she also may want you to have allergy tests after you get better from the allergic reaction. These tests will help you find out which types of insect stings you are most allergic to.
Treatment for insect sting allergies depends on how bad your reaction is. Most of the time, you can treat mild allergic reactions with home care. Try cold packs and medicines for pain, swelling, and itching. Most people don't need epinephrine or allergy shots for these mild allergic reactions.
A severe reaction (anaphylaxis) can be deadly and needs emergency care.
If you have severe reactions, you should carry an allergy kit. It includes antihistamine pills and an epinephrine shot, such as an EpiPen. You may also want to try allergy shots, called immunotherapy, to help prevent worse allergic reactions in the future.
To reduce your chances of being stung:
Frequently Asked Questions
Learning about allergies to insect stings:
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Symptoms of an allergic reaction to insect stings vary from mild to life-threatening. The severity of your allergic reaction depends on your sensitivity to the allergens in the venom—not necessarily on the number of stings or how often you have been stung in the past.
It is normal to have some immediate swelling, redness, pain, and itching at the site of an insect sting—toxins from the insect's venom enter the skin when you are stung. Normal symptoms from insect stings may last from a few hours to a few days, don't spread beyond the area of the bite, and include:
A normal reaction to fire ant stings is slightly different. Fire ants sting numerous times in a cluster or ring, usually on a person's feet and legs because these are closest to the ground. The stings cause pain, redness, itching, and swelling at the site of the stings. Also, within several hours of being stung, small clear blisters appear and then fill with fluid within 24 hours. Fire ants are not found in Canada, but they are common in the southeastern region of the United States, especially along the gulf coast.
A large local reaction is when redness and swelling from an allergic reaction spread outward from the site of the sting. The reaction may affect only the area around the sting itself (such as your hand or forearm). Or it may involve an entire limb or a broad area of the body. A large local reaction does not affect the entire body. It often will spread to cross the major joints on either side of the sting, such as the elbow and shoulder if you are stung on the upper arm. You may also experience a low fever, nausea, or fatigue. Symptoms usually occur 12 to 24 hours after you are stung and go away in 5 to 10 days.1
People who have large local reactions to stings sometimes have a more severe local reaction each time they are stung. But for both children and adults, the risk of having a systemic (whole-body) reaction is relatively low, from 1% to 3%.1
Symptoms of a systemic allergic reaction develop in a different location than where you were stung and range from moderate to life-threatening. A severe systemic reaction is called anaphylaxis and requires immediate medical treatment.
Common systemic allergic reaction symptoms include:
Serious, life-threatening systemic allergic reaction (anaphylaxis) symptoms can include the symptoms above and:
Systemic reactions usually develop within 15 to 30 minutes or, sometimes, up to an hour after being stung. In some cases, anaphylaxis may continue or recur for 6 to 24 hours after a person is stung, and continued intensive treatment may be needed.1
If you had a previous systemic allergic reaction to a sting, you are at great risk of having a similar reaction if you are stung again.
Every systemic reaction to an insect sting should be considered a medical emergency. If you have a systemic allergic reaction, you should be observed in a clinic or emergency room afterwards to make sure you do not develop severe symptoms. If you have symptoms of a severe allergic reaction, seek immediate medical care by calling 911 or other emergency services.
Your doctor may refer you to a specialist, such as an allergist (immunologist), who will perform allergy tests, such as skin tests or blood tests, to identify your allergies. The skin tests may involve many skin pricks to see what kinds of insect stings you are allergic to.
It is possible that you will not show any sensitivity to allergens in allergy tests even after you have had an allergic reaction to an insect sting.2 Your doctor may recommend that you repeat these tests in 3 months.
Allergies to insect stings are treated by avoiding the insects that cause the allergy, treating mild cases with medicines such as antihistamines, and understanding how and when to use an allergy kit for serious reactions.
Special care must be taken with children who have insect sting allergies. A child with a severe allergy may have life-threatening anaphylactic reactions to even tiny amounts of venom from the insect. Your child should always wear a medical alert bracelet and carry an allergy kit. Children at risk for severe allergic reactions should keep allergy kits at school or daycare and at home. Make sure that all caregivers—such as school administrators, teachers, friends, and coaches—know about the insect sting allergy, where the allergy kit is kept, and how and when to give the epinephrine injection. Also, make sure they have a plan to transport your child to the hospital. Older, mature children should be taught to give self-injections.
Immediate treatment for an allergic reaction to an insect sting depends on the type and severity of your symptoms.
For the normal reaction that most people have to a sting, medical treatment is usually not needed. An ice pack or a cold compress and non-steroidal anti-inflammatory drugs (NSAIDs) such as ASA or ibuprofen may relieve some of the swelling and pain. Non-prescription pain relievers such as acetaminophen (for example, Tylenol) may reduce pain, and oral antihistamines such as diphenhydramine (for example, Benadryl) can reduce itching. Antihistamines are not recommended for children younger than 6 years. Don't give antihistamines to your child unless you've checked with the doctor first. And do not give ASA to anyone younger than 20 because of the risk of Reye syndrome.
Treatment for large local allergic reactions usually consists of:
Systemic (whole-body) allergic reactions to a sting are considered a medical emergency. Immediate treatment is needed and may include:
Treatment for anaphylaxis—the most severe systemic allergic reaction, one that can be life-threatening—is designed to keep your airway open and relieve other breathing or heart problems that can occur, especially if there are signs of shock. In addition to epinephrine and an antihistamine, treatment for anaphylaxis may include:
If you had anaphylaxis, you will normally need to stay in the hospital for 8 to 12 hours before being released. Symptoms of anaphylaxis can recur after several hours, so you may need additional medicine or treatment.
If testing and examinations confirm that you are allergic to insect stings, long-term treatment usually includes:
If you have a history of systemic allergic reactions, you may consider treatment with a series of shots (immunotherapy) to reduce your sensitivity to the stinging insect's venom and lower your risk of a severe reaction. Immunotherapy is usually not needed for adults or children who have only a large local reaction to a sting. But anyone who experiences increasingly severe large local reactions with each new sting may want to consider immunotherapy. Talk with your doctor or allergy specialist to see whether immunotherapy is appropriate for you.
Knowing which insect venom triggers your allergies and avoiding those insects is the best way to avoid allergic reactions to the stings. Unfortunately, it can be difficult to avoid insects, especially if you spend time outdoors.
Home treatment for allergic reactions to insect stings includes:
For normal, local sting reactions and large local allergic reactions, try the following:
Any systemic reaction (anaphylaxis) to an insect sting should be considered a medical emergency. If you have symptoms of a severe allergic reaction—such as difficulty breathing, dizziness, swelling of your tongue or throat, or abdominal cramps—call 911 or other emergency services immediately.
If your doctor has prescribed an allergy kit, use the kit if:
Antihistamines can help reduce your symptoms. But antihistamines may not be strong enough for severe reactions. And they shouldn't be given to children unless the doctor has said it's okay. Even though it can be scary to give yourself an epinephrine shot, it may be the only way to stop a severe reaction.
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The American Academy of Allergy, Asthma, and Immunology publishes an excellent series of pamphlets on allergies, asthma, and related information. It also provides physician referrals.
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Anaphylaxis Canada provides information, support services, and educational materials regarding severe allergic reactions (anaphylaxis), and advocates for the needs of individuals and families living with anaphylaxis. The organization also conducts and supports research related to anaphylaxis. The Web site includes a special section, Safe4Kids, for children.
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The Asthma and Allergy Foundation of America (AAFA) provides information and support for people who have allergies or asthma. The AAFA has local chapters and support groups. And its Web site has online resources, such as fact sheets, brochures, and newsletters, both free and for purchase.
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The Canadian Allergy, Asthma, and Immunology Foundation (CAAIF) provides information and education programs for Canadians with allergy, asthma, and allergic diseases, and supports asthma research in these areas.
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This Web site is sponsored by the Nemours Foundation. It has a wide range of information about children's health, from allergies and diseases to normal growth and development (birth to adolescence). This Web site offers separate areas for kids, teens, and parents, each providing age-appropriate information that the child or parent can understand. You can sign up to get weekly e-mails about your area of interest.
- Golden DB (2009). Insect allergy. In NF Adkinson Jr et al., eds., Middleton's Allergy: Principles and Practice, 7th ed., vol. 2, pp. 1005–1017. Philadelphia: Mosby Elsevier.
- Golden DBK, et al. (2001). Insect sting allergy with negative venom skin test responses. Journal of Allergy and Clinical Immunology, 107(5): 897–901.
Other Works Consulted
- Golden DBK (2007). Allergic reactions to hymenoptera. In DC Dale, DD Federman, eds., ACP Medicine, section 6, chap. 15. New York: WebMD.
- House H (2006). Insect bites and stings. In MR Dambro, ed., Griffith's 5-Minute Clinical Consult, pp. 590–591. Philadelphia: Lippincott Williams and Wilkins.
- Reisman RE (2007). Insect sting allergy. In P Lieberman, JA Anderson, eds., Allergic Diseases Diagnosis and Treatment, 3rd ed., vol. 1, pp. 71–81. Totowa, NJ: Humana Press.
- Schwartz LB (2008). Systemic anaphylaxis, food allergy, and insect sting allergy. In L Goldman, D Ausiello, eds., Cecil Textbook of Medicine, 23rd ed., vol. 3, pp. 1947–1950. Philadelphia: Saunders Elsevier.
- Bernstein IL, et al. (2008). Allergy diagnostic testing: An updated practice parameter. Annals of Allergy, Asthma, and Immunology, 100(3, Suppl 3): S1–S148.
- Canadian Allergy, Asthma, and Immunology Foundation (1995). Anaphylaxis in schools and other child care settings. Available online: http://www.csaci.ca/index.php?page=360.
- Tankersley MS (2008). The stinging impact of the imported fire ant. Current Opinion in Allergy and Clinical Immunology, 8(4): 354–359.
|Primary Medical Reviewer||E. Gregory Thompson, MD - Internal Medicine|
|Primary Medical Reviewer||Brian D. O'Brien, MD - Internal Medicine|
|Specialist Medical Reviewer||Rohit K Katial, MD - Allergy and Immunology|
|Last Revised||June 7, 2010|
Last Revised: April 7, 2012
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