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Bee-Wasp Sting (Anaphylaxis)MANAGEMENT

ENVIRONMENTAL AND EXPOSURE PRESENTATIONS · 12 SECTIONS

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810 items

☷ Legend

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Cardiovascular Presentations71▾

Respiratory Presentations52▾

Neurological Presentations83▾

Gastrointestinal Presentations74▾

Genitourinary and Reproductive Presentations48▾

Infectious Disease Presentations148▾

Trauma Presentations89▾

Toxicologic Presentations80▾

Psychiatric Presentations26▾

Musculoskeletal and Rheumatologic Presentations96▾

Dermatology Presentations23▾

Environmental and Exposure Presentations27▾

Acute Mountain Sickness Arterial Gas Embolism Bee-Wasp Sting (Anaphylaxis)Chilblains Ciguatera Fish Poisoning Coral Cut Decompression Sickness Electrical Burn Injury Envenomation (snake, spider, insect)High Altitude Cerebral Edema (HACE)High Altitude Pulmonary Edema (HAPE)High-altitude illness Hypothermia Hypothermia (Mild)Hypothermia (Severe)Immersion Foot Lightning Strike Injury Scombroid Fish Poisoning Scorpion Envenomation Sea Urchin Injury Shark Bite Snake Envenomation Spider Bite (Black Widow)Spider Bite (Brown Recluse)Stingray Spine Injury Tick paralysis White Phosphorus Burn

Hematologic and Oncologic Presentations36▾

Pediatric-Specific Presentations19▾

Endocrine and Metabolic Presentations45▾

ENT and Maxillofacial Presentations27▾

Ophthalmologic Presentations19▾

Obstetric Presentations23▾

Systemic and Miscellaneous Presentations17▾

01Approach to the Critical Patient/attcp64

Airway and breathing

›Airway threat recognition

›Stridor or hoarseness

›Indicates supraglottic edema

›Prepare for early definitive airway

›Tongue or uvular swelling

›Indicates impending airway loss

›Oral intubation window may close rapidly

›Prepare for RSI if upper airway edema is progressive

›Videolaryngoscopy preferred

›Surgical airway backup at bedside

›Oxygenation targets

›SpO2 target >= 95%

›High-flow O2 via non-rebreather mask

›HFNC if hypoxemia persists after epinephrine

›Nebulized albuterol if bronchospasm

›Wheezing unresponsive to epinephrine

›Repeat every 20 minutes as needed

Circulation and hemodynamics

›Shock recognition and response

›Anaphylactic shock physiology

›Distributive vasodilation from mast cell mediators

›Relative hypovolemia

›Hypotension threshold: SBP < 90 mmHg adults; < 70 mmHg + (2 x age) children

›Immediate supine positioning with legs elevated

›IV NS bolus 1-2 L adult or 10-20 mL/kg pediatric

›Epinephrine IM 0.3-0.5 mg anterolateral thigh immediately

›Do not delay for IV access

02History/hx78

Sting event details

›Insect identification

›Honeybee — leaves barbed stinger in skin

›Higher systemic reaction risk than vespids

›Stinger removal by scraping (not squeezing)

›Wasp, yellow jacket, hornet — no retained stinger

›Can sting multiple times

›Yellow jackets most common cause of sting anaphylaxis in North America

›Fire ant — multiple stings, characteristic vesicle pattern

Symptom timeline

›Onset timing after sting

›Rapid onset < 5 minutes

›Associated with more severe reactions

›Immediate resuscitation bay placement

›Delayed onset 15-60 minutes

›More typical presentation

›Biphasic risk still applies

›Onset > 60 minutes — atypical, reconsider diagnosis

Symptom characterization

›Cutaneous symptoms

›Pruritus

›Urticaria

›Flushing

›Angioedema location (lips, tongue, periorbital)

›Respiratory symptoms

›Throat tightness

›Hoarseness

›Dyspnea

03Physical Exam/exam62

Vital signs

›Hemodynamic assessment

›Tachycardia (most common initial finding)

›Bradycardia is late or vasovagal sign

›Distinguish from vasovagal syncope by urticaria presence

›Hypotension

›SBP < 90 mmHg or 30 mmHg below baseline

›Orthostatic drop

›Tachypnea and hypoxia

›SpO2 trend

›Respiratory rate

Cutaneous exam

›Skin findings

›Generalized urticaria

›Distribution and extent

›Dermographism

›Angioedema

›Lip and tongue swelling

›Periorbital edema

›Asymmetric facial swelling

›Flushing and erythema

›Blanching vs. non-blanching

›Widespread erythroderma

›Sting site inspection

›Retained honeybee stinger

›Erythema and local swelling extent

›Large local reaction > 10 cm

04Differential Diagnosis/ddx70

Anaphylaxis mimics

›Vasovagal syncope

›Differentiation features

›Bradycardia with pallor

›No urticaria or angioedema

›No respiratory symptoms

›ICD-10: R55

›Panic or anxiety attack

›Differentiation features

›Tachycardia with hyperventilation

›No urticaria or hypotension

›Normal SpO2

›ICD-10: F41.0

Allergic spectrum disorders

›Large local reaction

›Features

›Erythema > 10 cm at sting site only

›No systemic features

›Occurs in 19% of sting reactions

›ICD-10: T63.441A

›Urticaria without anaphylaxis

›Features

›Skin-only manifestation

›No hemodynamic compromise

›No respiratory involvement

›ICD-10: L50.0

Angioedema variants

›Hereditary angioedema (HAE)

05Laboratory Tests/lt52

Serum tryptase

›Diagnostic utility

›Draw within 2 hours of symptom onset ideally

›Peak at 60-90 minutes post-reaction

›Half-life 90-120 minutes

›Diagnostic threshold > 11.4 ng/mL or >= (1.2 x baseline) + 2 ng/mL

›Elevated tryptase supports anaphylaxis diagnosis

›Normal tryptase does not exclude anaphylaxis

›Baseline tryptase at follow-up visit (asymptomatic state)

›Baseline > 8 ng/mL prompts evaluation for mast cell disorder

›Hereditary alpha-tryptasemia in 10-20% of sting anaphylaxis patients

Complete blood count

›CBC indications

›Eosinophilia

›Suggests allergic or parasitic etiology

›Not specific for anaphylaxis

›Hemoconcentration

›Plasma extravasation in severe anaphylaxis

›Elevated hematocrit

Metabolic panel

›BMP and renal function

›Acute kidney injury screen

›Especially with prolonged hypotension

›Massive envenomation with rhabdomyolysis

›Electrolytes

›Hypokalemia from epinephrine-driven intracellular shift

›Bicarbonate for acid-base status

06Diagnostic Tests/dt70

Scoring Systems

›World Allergy Organization anaphylaxis grading

›Grade 1: skin/mucosal symptoms only

›No systemic compromise

›Lowest risk for adverse outcome

›Grade 2: mild systemic involvement

›Cardiovascular or respiratory mild symptoms

›Epinephrine indicated

›Grade 3: life-threatening anaphylaxis

›Cardiovascular collapse or severe bronchospasm

›Immediate aggressive resuscitation

›Grade 4: cardiac arrest

›ACLS protocol activation

›Epinephrine 1 mg IV push

›Mueller classification for systemic reactions

›Grade I: generalized urticaria, pruritus, malaise, anxiety

›Mild systemic reaction

›Epinephrine autoinjector indication

›Grade II: angioedema, chest tightness, nausea, vomiting

›Moderate systemic reaction

›Epinephrine IM immediately

›Grade III: dyspnea, stridor, wheezing, abdominal pain, vomiting, dizziness

›Severe systemic reaction

›Emergency intervention required

›Grade IV: cyanosis, hypotension, loss of consciousness, shock

›Near-fatal anaphylaxis

›Full resuscitative measures

›Biphasic reaction risk stratification

07Disposition/dispo55

Observation requirements

›Minimum observation periods

›Mild, rapidly resolving reaction without high biphasic risk

›Minimum 1-hour observation

›Complete symptom resolution required

›Standard anaphylaxis per NIAID guidelines

›4-6 hours post-epinephrine administration

›Vital sign stability throughout

›Severe presentation with respiratory compromise or hypotension

›6-12+ hours observation minimum

›Consider admission

Admission criteria

›Indications for hospital admission

›Refractory anaphylaxis

›Multiple epinephrine doses required

›IV epinephrine used

›Hemodynamic instability

›Persistent hypotension despite fluids

›Vasopressor requirement

›Airway compromise

›Intubation performed

›Significant residual upper airway edema

›High-risk comorbidities

›Severe asthma

›Cardiovascular disease

›Mastocytosis

›Protracted or prior biphasic reactions

08Treatment/t107

Epinephrine (first-line)

›Epinephrine IM — first-line, no contraindications in anaphylaxis

›Adult dosing

›Epinephrine 1:1000 (1 mg/mL) 0.3-0.5 mg IM

›Anterolateral mid-thigh preferred site

›Repeat every 5-15 minutes as needed

›Pediatric dosing

›0.01 mg/kg IM (max 0.5 mg per dose)

›Anterolateral thigh preferred site

›Repeat every 5-15 minutes

›No absolute contraindications in anaphylaxis

›Safe in cardiovascular disease

›Safe in elderly patients

›Safe in pregnancy

Epinephrine IV (refractory)

›IV epinephrine for refractory anaphylaxis

›Indication: failure after 2-3 IM doses with IV access and monitoring

›Continuous cardiac monitoring mandatory

›Dilute to 0.1 mg/mL (1 mg in 10 mL NS) for controlled bolus

›IV infusion protocol

›1 mg epinephrine in 250 mL NS = 4 mcg/mL

›Start at 1-4 mcg/min

›Titrate to MAP > 65 mmHg and HR response

›Maximum 10 mcg/min

›Avoid IV bolus unless cardiac arrest

›Risk of dysrhythmia and hypertensive emergency

›ACEP Level B recommendation

Airway management

›Airway interventions

›Supplemental O2 via non-rebreather 10-15 L/min

›Target SpO2 >= 95%

›Downgrade to nasal cannula once stable

›Early intubation if upper airway edema progresses

›Videolaryngoscopy preferred

›RSI with ketamine 1.5 mg/kg IV and succinylcholine 1.5 mg/kg IV

›Surgical airway kit at bedside

›Nebulized albuterol 2.5-5 mg for bronchospasm

›Every 20 minutes as needed

›Ipratropium 0.5 mg nebulized for refractory bronchospasm

Fluid resuscitation

›IV fluids for distributive shock

›Adult bolus

›NS or LR 1-2 L rapid IV bolus

›Repeat if hemodynamic response inadequate

›Pediatric bolus

›10-20 mL/kg NS rapid IV bolus

›Reassess after each bolus

›Avoid excessive fluids if pulmonary edema develops

›B-lines on lung ultrasound

›Cardiogenic component (Kounis syndrome)

Antihistamines (adjunctive)

›H1 antihistamines — adjunctive only, do not replace epinephrine

›Diphenhydramine 25-50 mg IV or IM

›Onset 15-30 minutes (too slow as primary therapy)

›For pruritus and urticaria relief

›Cetirizine 10 mg PO as alternative in mild reactions

›Non-sedating

›10 mg single dose

›H2 antihistamines — adjunctive

›Famotidine 20 mg IV

›Mild additive benefit with H1 blockade

›Evidence for improved outcomes limited

Corticosteroids (adjunctive)

›Corticosteroids — limited evidence for biphasic prevention

›Methylprednisolone 1-2 mg/kg IV (max 125 mg)

›No proven benefit for biphasic reaction prevention

›May be useful for prolonged bronchospasm

›Dexamethasone 0.15 mg/kg IV as alternative

›Longer duration of action

›Class IIb recommendation — insufficient evidence to routinely recommend

Glucagon (beta-blocker reversal)

›Glucagon for epinephrine-resistant anaphylaxis

›Indication: anaphylaxis in patients on beta-blockers

›Bypasses beta-receptor blockade

›Acts through adenylyl cyclase

›Adult dosing

›Glucagon 1-5 mg IV over 5 minutes

›Infusion 5-15 mcg/min to maintain response

›Anticipate emesis — airway positioning

›Supine with suction ready

›Semi-recumbent if no hypotension

Vasopressors (refractory)

›Vasopressor protocol for refractory anaphylactic shock

›Norepinephrine

›Start 0.1 mcg/kg/min via central or peripheral IV

›Titrate to MAP >= 65 mmHg

›Maximum 2 mcg/kg/min

›Vasopressin

›0.03-0.04 units/min fixed dose

›Adjunct to norepinephrine

›May provide synergistic benefit

›Dopamine alternative if norepinephrine unavailable

›5-20 mcg/kg/min

›Less evidence than norepinephrine

Stinger removal

›Honeybee stinger removal

›Scrape with credit card or fingernail

›Do not grasp or squeeze

›Squeezing injects additional venom

›Remove immediately on identification

›Rapid removal reduces venom load

›No evidence one removal technique superior to another

Long-term prevention

›Epinephrine autoinjector prescription

›Prescribe minimum two devices at discharge

›EpiPen 0.3 mg for adults >= 30 kg

›EpiPen Jr 0.15 mg for children 15-30 kg

›Education on technique and indications

›Inject at first sign of systemic reaction

›Do not wait for hives to appear

›Venom immunotherapy (VIT)

›Indication: all patients with systemic sting anaphylaxis and positive venom IgE

›Reduces systemic reaction risk from 30-60% to < 5%

›Evidence Level A (Class I recommendation)

›Duration: minimum 5 years standard protocol

›Lifelong VIT for mastocytosis patients

›Efficacy up to 98% in preventing future sting anaphylaxis

09Special Populations/sp62

Pregnancy

›Anaphylaxis in pregnancy

›Epinephrine remains first-line — no contraindication

›Maternal survival takes priority

›Uteroplacental vasoconstriction risk is outweighed by maternal benefit

›0.3-0.5 mg IM anterolateral thigh — same dosing as non-pregnant

›Positioning considerations

›Left lateral decubitus for uterine displacement

›After 20 weeks gestation

›Reduces aortocaval compression

›Fetal monitoring

›Continuous fetal heart rate monitoring during resuscitation

›OB consultation immediately

›Perimortem cesarean section at >= 20 weeks if cardiac arrest

›Adjunctive therapies

›Diphenhydramine: Category B, generally acceptable

›Corticosteroids: acceptable in pregnancy

›H2 blockers: famotidine acceptable

›VIT safety in pregnancy

›Do not initiate VIT during pregnancy

›Continue existing VIT if already tolerating maintenance dose

Geriatric

›Anaphylaxis in older adults

›Risk profile

›Higher case fatality rate vs. younger adults

›More frequent cardiovascular comorbidities

›More frequent beta-blocker and ACE inhibitor use

›Epinephrine dosing — same dose as younger adults

10Background/b95

Epidemiology

›Prevalence and incidence

›Hymenoptera venom anaphylaxis occurs in 1-3% of all stings

›Large local reactions in 19% of general population

›True anaphylaxis less frequent

›Sting-related anaphylaxis deaths

›Estimated 40-100 deaths per year in United States

›Underestimated due to sudden unexpected death classification

›Cardiovascular disease and mastocytosis increase mortality risk

›Recurrence risk with re-sting

›Prior systemic reaction: 30-60% recurrence without VIT

›VIT reduces recurrence to < 5% (Class I evidence)

›At-risk populations

›Male sex and older age independently increase mortality

›Greater outdoor occupational exposure in males

›Reduced physiologic reserve in elderly

›Hereditary alpha-tryptasemia (HaT)

›Found in 10-20% of sting anaphylaxis patients

›vs. 6% of general population

›Associated with elevated baseline tryptase

Pathophysiology

›IgE-mediated sensitization and activation

›Primary sensitization phase

›Prior sting exposure leads to venom-specific IgE production

›IgE binds high-affinity receptors on mast cells and basophils

›No symptoms during sensitization

›Re-exposure and degranulation

›Venom antigen crosslinks IgE-bound receptors

›Rapid mast cell degranulation (seconds to minutes)

›Histamine, tryptase, leukotrienes, prostaglandins released

›Non-IgE-mediated mechanisms

›Direct mast cell activation by venom components

›Complement activation with massive envenomation

›Accounts for some reactions without prior sting history

›Mediator effects

›Histamine effects

›H1: vasodilation, bronchoconstriction, pruritus, urticaria

›H2: gastric acid secretion, cardiac effects

›Cardiovascular collapse mechanism

›Profound vasodilation and capillary leak

›Relative hypovolemia

›Direct myocardial depression in severe reactions

›Airway involvement

›Upper airway: angioedema from bradykinin and histamine

›Lower airway: bronchoconstriction from leukotrienes and histamine

›Biphasic reaction mechanism

›Second mediator release wave

›Late-phase arachidonic acid metabolites

›Occurs 1-72 hours after initial reaction

›Rate approximately 1-7%

›Predictors of biphasic reaction

›Delayed epinephrine administration

›Severity of initial reaction

›Inadequate initial treatment

›Venom composition

›Major venom allergens

›Phospholipase A2 (Api m1) — major honeybee allergen

›Hyaluronidase facilitates venom spread

›Melittin (honeybee) causes direct cell membrane disruption

›Antigen 5 (vespids) — major wasp allergen

›Species cross-reactivity

›Bees and vespids share hyaluronidase cross-reactivity

›Vespids (wasp, yellow jacket, hornet) share antigen 5 cross-reactivity

›Fire ant venom is distinct

Therapeutic Considerations

›Epinephrine pharmacology

›Mechanism of action

›Alpha-1: vasoconstriction, reduces mucosal edema

›Beta-1: positive inotropy and chronotropy

›Beta-2: bronchodilation, suppresses further mediator release

›IM vs IV pharmacokinetics

›IM anterolateral thigh achieves peak concentration faster than deltoid

›IM onset 5-10 minutes

›IV onset within 1-2 minutes but higher risk profile

›Why delayed epinephrine is the primary modifiable mortality risk factor

›Irreversible angioedema progression

›Cardiovascular collapse may precede treatment

›Every minute of delay worsens outcomes

›Beta-blocker and epinephrine interaction

›Beta-receptor blockade reduces epinephrine effectiveness

›Paradoxical bradycardia can occur (unopposed alpha effect)

›Hypertension with reflex bradycardia possible

›Glucagon bypasses beta-blockade via adenylyl cyclase

›Alternative for refractory hypotension

›High-dose glucagon protocol required

›Venom immunotherapy evidence

›Mechanism

›Induces immune tolerance to venom antigens

›Shift from IgE to IgG4 immune response

›Reduces mast cell and basophil reactivity

›Efficacy

›80-98% protection against future systemic reactions

›Class I evidence base (ACAAI Practice Parameter)

›Duration: minimum 5 years; lifelong in mastocytosis

›Mastocytosis and VIT

›Lifelong VIT strongly recommended

›Higher risk without ongoing immunotherapy

›Cytoreductive therapy may additionally reduce anaphylaxis risk

11Patient Discharge Instructions/pdi51

copy discharge instructions

›What happened to you today

›You had a severe allergic reaction (anaphylaxis) to a bee or wasp sting

›This is a life-threatening emergency and you were treated with epinephrine

›You will need follow-up care to prevent this from happening again

›Your medications

›You were prescribed epinephrine autoinjectors (EpiPen)

›Carry TWO autoinjectors with you at all times

›Check expiration dates regularly

›Do not leave them in hot cars as heat degrades the medication

›How to use your EpiPen

›Remove blue safety cap

›Press orange tip firmly into outer thigh (can inject through clothing)

›Hold for 3 seconds, then rub the area

›Call 911 and go to the nearest emergency room immediately after use

›Warning signs — return to the emergency room or call 911 immediately

›Throat tightness or difficulty breathing

›Can start hours after the initial reaction (biphasic reaction)

›Use your EpiPen and call 911

›Hives, swelling, or itching returning

›Within 72 hours of the initial reaction

›Do not wait — use EpiPen if symptoms are progressing

›Lightheadedness, fainting, or feeling like your heart is racing

›May indicate low blood pressure from ongoing reaction

›Lie flat and call 911

›Nausea, vomiting, or abdominal pain worsening

›Can be part of biphasic reaction

›Seek emergency care

12References/r44

Guidelines and key sources

›Golden DBK, Wang J, Waserman S, et al.

›Anaphylaxis: A 2023 Practice Parameter Update

›Annals of Allergy, Asthma and Immunology. 2024

›Biphasic reaction rates 1-7%, observation periods, VIT indications

›Golden DB, Demain J, Freeman T, et al.

›Stinging Insect Hypersensitivity: A Practice Parameter Update 2016

›Annals of Allergy, Asthma and Immunology. 2017

›Recurrence risk 30-60%, rapid onset severity correlation, medication interactions

›Pflipsen MC, Vega Colon KM.

›Anaphylaxis: Recognition and Management

›American Family Physician. 2020

›IV epinephrine protocols, glucagon dosing, adjunctive therapies

›Casale TB, Burks AW.

›Hymenoptera-Sting Hypersensitivity

›New England Journal of Medicine. 2014

›Mastocytosis and VIT evidence, venom allergen composition

›Herness J, Snyder MJ, Newman RS.

›Arthropod Bites and Stings

›American Family Physician. 2022

›Species identification, sting epidemiology, large local reactions

›Stoevesandt J, et al.

›Risk Factors and Indicators of Severe Systemic Insect Sting Reactions

›Allergy. 2020

›Beta-blocker and ACE inhibitor risk, tryptase thresholds

›Long B, Gottlieb M.

›Emergency Medicine Updates: Anaphylaxis

›American Journal of Emergency Medicine. 2021

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Reviewed by SymptomDx Medical Team · Last reviewed August 18, 2026

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