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Wasp Stings Follow-up

  • Author: Carl A Mealie, MD, FACEP, FAAEM; Chief Editor: Joe Alcock, MD, MS  more...
Updated: Sep 22, 2015

Further Outpatient Care

Direct outpatient care at preventing any further reaction.

Provide patient education to reduce high-risk activities that may lead to exposure (see Activity).

Prescribe self-administered auto-injectors (eg, EpiPen) to patients who have the potential for a severe reaction or who may be away from readily available medical assistance.

Refer patients to an allergist for desensitization. This follow-up referral should be made expeditiously. The factors to consider are include initial reaction of the patient and the patient's risk of being stung again, such as the patient's occupation and time of year.


Further Inpatient Care

All patients who present with a moderate-to-severe reaction to a wasp sting that required treatment should be observed. A rebound or biphasic reaction has been reported in 1-20% of patients as initial treatment wears off.


Proactively treat patients who experience throat tightness resulting from a wasp sting. A treatment spectrum progresses from the asymptomatic patient to the patient with symptoms of mild throat tightness to the patient in respiratory distress from angioedema.

Assess the airway as soon as possible in the patient who experiences throat tightness. Although cross-lateral neck radiography to assess soft tissue can be helpful to rule out gross swelling, it has several disadvantages. It may not reveal early swelling. If transferred to the radiology department for the radiograph, the patient should be accompanied by both an intubation tray and a physician capable of managing the airway.

The airway is best visualized by either an otorhinolaryngologist or an emergency department (ED) physician using a Machida scope or, if a flexible fiberoptic scope is not available, indirect laryngoscopy. An intubation tray must be available at the bedside.

Supplemental oxygen supplied by a humidified cool mist is often helpful in the patient with minimal inflammation who does not need immediate intubation and is being observed.


Continually monitor patients with pulse oximetry. Peak flow measurement may help evaluate the progression of bronchial spasm.

Evidence of poor ventilation with decreasing oxygen saturations, poor air movement, wheezing, poor air exchange, prolongation of the expiratory phase, or increased work of breathing requires aggressive management.

A nebulized beta agonist (eg, albuterol) can reduce bronchial spasm and improve oxygenation.

Use methylprednisolone 125 mg IV to decrease the inflammatory response of the airways.


The cardiac rate and rhythm and the intravascular fluid compartment are 2 components of circulation that must be monitored.

Put the patient on a cardiac monitor and observe in an area where the patient can be intubated if necessary.

The BP must be monitored continuously because of the release of multiple factors in anaphylaxis that can reduce capillary integrity, increase capillary permeability, and subsequently decrease the amount of fluid in the vascular compartment and, at the same time, decrease the systemic vascular resistance.


Inpatient & Outpatient Medications

Patients should be taught the use of the EpiPen 0.3 mg auto-injector or the EpiPen Jr 0.15 mg before they leave the ED. The patient should be taught the indications for the use of the EpiPen such as the signs and symptoms of a severe allergic or anaphylactic reaction. They should be taught to inject the EpiPen into the anterolateral aspect of the thigh and that once the auto-injector is triggered to maintain the auto-injector in place for several seconds until all the medication is injected. The patient should be advised to keep one EpiPen in the home and one on his or her person at all times. Epinephrine is light sensitive and should be stored between 15o -30o C (59o -86o F).[12] Placement of an EpiPen in the car where internal summer temperatures can be well over 100o F is not recommended.

Oral H1 blockers (eg, diphenhydramine, hydroxyzine) and corticosteroids (eg, prednisone, methylprednisolone) also may be helpful.



Transfer the patient to the nearest facility capable of providing critical care monitoring if critical care monitoring cannot be performed at the facility initially treating the patient (in accordance with the current standards established by the Emergency Medical Treatment and Labor Act [EMTALA]).

A person capable of aggressively managing the patient's airway and monitoring and managing the patient's cardiopulmonary function should accompany the patient.

The transporter should have all the equipment and medication necessary to resuscitate the patient.



Teach the patient how to modify behavior, to dress, and to use toiletries and perfumes appropriately (see Activity).

Refer the patient to an allergist for desensitization to Hymenoptera venom. Desensitization by venom immunotherapy can be accomplished by the injection of depot extracts using a slow and conventional schedule, which minimizes local and systemic side effects, or it can be accomplished rapidly by using a rush protocol with aqueous extracts if protection needs to be achieved rapidly. However, the incidence of severe reactions makes the rush protocol less than ideal for an outpatient procedure and requires hospitalization.[13]

Venom immunotherapy can reduce the relative risk of a future severe reaction to 0.1 as well as reduce the severity of the local reaction. Unfortunately, health economic analysis shows that it is not cost effective because of the infrequency that people are stung. In patients who are at risk for frequent stings, such as beekeepers, venom immunotherapy improves the quality of their life and can be cost effective.[14]

Up to 25% of patients who are on venom immunotherapy will still develop a severe anaphylactic reaction when re-stung.[13]

Prescribe auto-injectors (eg, EpiPen) and oral H1 blockers (eg, diphenhydramine, hydroxyzine).



Consider local wound infection in any wasp sting site that worsens, persists, or partially resolves only to swell up with increased redness, swelling, or pain. Other symptoms and signs that should be elicited include fever, chills, red streaks extending proximally from the site, and purulent drainage from the site.

Wasp stings have also been associated with acute renal failure in children[15] as well as the Kounis syndrome or allergic myocardial ischemia and infarction.[16, 17]



The prognosis for mild-to-moderate reactions is good. The goal is prevention of another exposure.


The anaphylactic reaction begins with the onset of symptoms distal to the wasp sting. The patient frequently feels increased anxiety, lightheadedness, headache, nausea, abdominal cramps, and palpitations. This is followed by objective findings of the patient appearing flushed, hypotensive, and tachycardic. This is due to the circulating levels of histamine and kinins that cause decreased systemic vascular resistance, increased capillary permeability, and resulting reduction of intravascular volume. The resulting reduction in perfusion pressure causes the neurologic symptoms of lightheadedness, syncope, and seizures.

Sensitization to Hymenoptera or wasp venom occurs in almost 1% of all stings. Each year, 90-100 deaths occur. Risk factors that tend to increase morbidity and mortality include age, cardiopulmonary risk factors, medication, and prior history of an allergic reaction to a Hymenoptera or wasp sting. Factors that favor a systemic reaction include multiple simultaneous wasp stings or single sequential wasp stings within several weeks. In most cases of Hymenoptera stings, death is the result of airway and respiratory compromise. Edema of the larynx, epiglottis, and supraglottic area is found in 69% of fatal cases. These structures are particularly vulnerable target areas because of their rich vascular supply. Prior history of sensitivity or an allergic reaction to a Hymenoptera sting places the patient at higher risk for another reaction.

Individuals who are atopic, individuals with a history of multiple allergies, and individuals who have had a prior anaphylactic reaction to a different allergen may be at increased risk for sensitization to their first Hymenoptera sting. The following factors also increase the risk of sensitization:


Children and elderly people are at increased risk. Infants and small children are at risk after multiple wasp stings because of the relatively large amount of venom per body mass. The smaller-diameter pediatric airway may also occlude more readily from edema. Elderly people may have poor cardiac reserves to compensate for the allergic reaction.

Cardiopulmonary risk factors

People with coronary artery disease, a history of ischemia, prior myocardial infarctions, or reduced cardiac ejection fractions may not be able to compensate for the increased insult to their circulatory system from circulating vasoactive peptides or from the catecholamines administered to resuscitate them. People with pulmonary disease (eg, asthma, chronic bronchitis, emphysema) may experience acute decompensation of the respiratory system because of increased bronchospasm or pulmonary edema.


Beta-blockers may increase morbidity and mortality because they inhibit attempts to improve cardiac output by either endogenously produced or exogenously administered catecholamines.

Calcium channel blockers may exacerbate the reduced systemic vascular resistance caused by circulating vasoactive peptides. The vasodilating antihypertensive agents may blunt the body's physiologic response to hypotension. As the circulating vasoactive chemical mediators of anaphylaxis cause vasodilation, the systemic vascular resistance falls. This causes a subsequent drop in the glomerular filtration rate, resulting in increased activation of the renin-angiotensinogen-angiotensin system.

Angiotensin-converting enzyme (ACE) inhibitors and ACE receptor blockers, as well as other vasodilators, can interfere with the body's ability to increase vasoconstriction and increase the systemic vascular resistance and the blood pressure (BP). The effect that nonsteroidal anti-inflammatory drugs (NSAIDs) and leukotriene inhibitors may have in modulating the severity or the morbidity and mortality of Hymenoptera-induced allergic reactions is unclear.


Patient Education

Teach the patient how to modify behavior, to dress, and to use toiletries and perfumes appropriately (see Activity and Outpatient Medication).

Contributor Information and Disclosures

Carl A Mealie, MD, FACEP, FAAEM Assistant Professor, Department of Emergency Medicine, Hofstra North Shore-LIJ School of Medicine; Chief of Operations, Department of Emergency Medicine, Long Island Jewish Medical Center

Carl A Mealie, MD, FACEP, FAAEM is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, American College of Physicians, American Medical Association, New York Academy of Medicine, Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.


Max Vernon Wisgerhof, II, MD Fellowship Program Director, Department of Endocrinology and Metabolism, Henry Ford Hospital

Max Vernon Wisgerhof, II, MD is a member of the following medical societies: American Thyroid Association, Endocrine Society

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Chief Editor

Joe Alcock, MD, MS Associate Professor, Department of Emergency Medicine, University of New Mexico Health Sciences Center

Joe Alcock, MD, MS is a member of the following medical societies: American Academy of Emergency Medicine

Disclosure: Nothing to disclose.

Additional Contributors

Lisa Kirkland, MD, FACP, FCCM, MSHA Assistant Professor, Department of Internal Medicine, Division of Hospital Medicine, Mayo Clinic; Vice Chair, Department of Critical Care, ANW Intensivists, Abbott Northwestern Hospital

Lisa Kirkland, MD, FACP, FCCM, MSHA is a member of the following medical societies: American College of Physicians, Society of Hospital Medicine, Society of Critical Care Medicine

Disclosure: Nothing to disclose.


Alan S Multz, MD Associate Professor of Clinical Medicine, Albert Einstein College of Medicine; Program Director, Internal Medicine Residency, Associate Chairman, Department of Medicine, Long Island Jewish Medical Center

Alan S Multz, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Chest Physicians, American College of Physicians, American Thoracic Society, and Society of Critical Care Medicine

Disclosure: Astellas Pharmaceutical Honoraria Consulting; Merck Pharmaceutical Honoraria Speaking and teaching; The Medicines Company Honoraria Consulting; Schering Plough Honoraria Speaking and teaching; Wyeth Pharmaceuticals Honoraria Speaking and teaching; Pfizer Honoraria Speaking and teaching

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A paper wasp (Randy Park, MD)
A paper wasp (Randy Park, MD)
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