Skip to Main Content


Wasps, bees, and stinging ants are members of the order Hymenoptera. Local and generalized reactions may occur in response to an encounter. Systemic toxicity may result from an allergic reaction or from massive envenomation as occurs classically with the so-called Africanized bees, which often attack in large numbers. Fire ant venom may cross-react in individuals sensitized to other Hymenoptera stings.

Clinical Features

Local reactions consist of pain, erythema, edema, and pruritus at the sting site. Severe local reactions may increase the likelihood of serious systemic reactions if the patient is reexposed. The local reaction to a fire ant sting consists of a sterile pustule that evolves over 6 to 24 hours, sometimes resulting in necrosis and scarring. Systemic reactions may include urticaria, angioedema, hypotension, and bronchospasm. In addition, those with massive envenomation may develop severe vomiting, diarrhea, rhabdomyolysis, myocardial injury, hepatic failure, and renal failure. Delayed reactions, which manifest 5 to 14 days post-envenomation, infrequently occur, but resemble serum sickness. Such illness is characterized by fever, malaise, headache, urticaria, lymphadenopathy, and polyarthritis.

Emergency Department Care and Disposition

  1. In addition to fluid resuscitation, patients with anaphylactic or anaphylactoid reactions should receive the following:

    1. Epinephrine 1:1000 concentration (0.3 to 0.5 cc IM in adults or 0.01 mg/kg up to a maximal dose of 0.5 cc in pediatrics). Patients whose symptoms persist despite IM epinephrine or those with evidence of shock should receive IV epinephrine as a continuous infusion.

    2. Endotracheal intubation should be performed if needed for airway edema.

    3. Steroids, such as methylprednisolone 2 mg/kg, with a maximal single dose of 125 mg, or prednisone 1 mg/kg orally, with a maximal single dose of 60 mg.

    4. H1 antagonists, such as diphenhydramine 1 mg/kg IV with a maximal single dose of 50 mg.

    5. H2 receptor antagonists, such as famotidine 0.5 mg/kg IV with a maximal dose of 40 mg.

    6. Bronchospasm should be treated with beta agonists, such as albuterol 2.5 to 5 mg via nebulization.

  2. Patients with urticaria, but no other systemic manifestations, should be treated with H1 and H2 blockers and steroids, but without epinephrine or albuterol.

  3. The stinger should be removed after the patient has been stabilized.

  4. Patients with a single sting who have only minor symptoms can be discharged home after a period of observation.

  5. For patients with multiple stings, disposition is as follows:

    1. Admit if more than 100 stings, substantial comorbidities, extremes of age, or severe systemic manifestations

    2. Patients with <100 stings, and who remain asymptomatic without laboratory evidence of complications (e.g., no rhabdomyolysis and normal renal function) following an observation period of 6 hours can be discharged from the Emergency Department.

  6. Refer all patients with Hymenoptera reactions to an allergist for further evaluation, prescribe a premeasured epinephrine injector (EpiPen®), and advise them to carry allergy alert identification. Instruct patients to use epinephrine ...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.