What is the immediate treatment for an adult or child with a history of insect bites and possible underlying allergies showing signs of anaphylaxis in the beginning stages?

Immediate Treatment for Beginning Stages of Anaphylaxis from Insect Bites

Administer intramuscular epinephrine immediately into the anterolateral thigh at the first recognition of anaphylaxis—this is the single most critical life-saving intervention and should never be delayed. 1

First-Line Emergency Actions

Remove the Stinger Immediately

• Flick or scrape the stinger away with a fingernail within the first 10-20 seconds to prevent injection of additional venom 1
• Avoid grasping the venom sac and pulling it out, as this can inject more venom 1

Administer Epinephrine Without Delay

• Epinephrine is the drug of choice and must be given promptly—delayed administration is associated with fatal outcomes 1, 2
• Dosing:
  • Adults: 0.3-0.5 mg intramuscular (IM) 1, 2
  • Children: 0.01 mg/kg IM, maximum 0.3 mg in prepubertal children 1
  • Autoinjector dosing: 0.15 mg for children 10-25 kg; 0.3 mg for those ≥25 kg 1
• Route: Intramuscular injection into the mid-outer thigh (vastus lateralis muscle) achieves faster and higher plasma concentrations than subcutaneous or arm injection 1, 2

Call for Emergency Medical Services

• Activate 911 or EMS immediately after administering epinephrine 1, 2
• Transport to emergency department is mandatory, even if symptoms improve 1

Position the Patient Appropriately

• Place patient supine (on their back) with lower extremities elevated if hypotension or cardiovascular symptoms are present 1, 2
• Allow position of comfort if respiratory distress or vomiting occurs 1
• Never allow the patient to stand, walk, or run—sudden postural changes can precipitate cardiovascular collapse 1, 2

Repeat Dosing Strategy

When to Repeat Epinephrine

• Administer a second dose of epinephrine 5-15 minutes after the first if symptoms persist or worsen 1, 2
• Be prepared to give multiple doses—repeat dosing may be required for persistent or recurrent symptoms 1
• There are no contraindications to epinephrine in anaphylaxis, even in patients with cardiovascular disease or those taking β-blockers 1, 2

Adjunctive Treatments (Only After Epinephrine)

Critical Caveat

Antihistamines and corticosteroids are NOT substitutes for epinephrine and should never delay its administration 1, 2

Supplemental Therapies

• H1 antihistamines (diphenhydramine): 1-2 mg/kg (maximum 50 mg) IV or oral for cutaneous symptoms 1, 3
• H2 antihistamines (ranitidine or famotidine): May be added as adjunct 1, 2
• Inhaled albuterol: For persistent bronchospasm despite epinephrine (2.5 mg nebulized in children, 3 mL in adults) 1, 2
• Supplemental oxygen: For all patients with respiratory distress or requiring multiple epinephrine doses 2
• IV fluids (normal saline): 1-2 liter bolus for persistent hypotension or incomplete response to epinephrine 1, 2
• Corticosteroids: May help prevent biphasic reactions but have no immediate effect on acute symptoms 1, 2

Recognition of Anaphylaxis in Beginning Stages

Clinical Criteria for Diagnosis

Anaphylaxis is likely when any one of the following occurs after insect bite/sting exposure 1:

1. Acute onset (minutes to hours) involving skin/mucosa PLUS at least one of:

   • Respiratory compromise (dyspnea, wheeze, stridor, hypoxemia) 1
   • Reduced blood pressure or end-organ dysfunction (hypotonia, syncope, incontinence) 1

2. Two or more of the following occurring suddenly:

   • Skin/mucosal involvement (urticaria, flushing, swollen lips/tongue) 1
   • Respiratory symptoms 1
   • Cardiovascular symptoms (tachycardia, hypotension, dizziness) 1
   • Persistent GI symptoms (crampy abdominal pain, vomiting) 1

Important Distinction in Children

Systemic reactions in children that are limited to skin only (cutaneous symptoms alone) are NOT considered anaphylactic reactions 1

Critical Pitfalls to Avoid

• Never delay epinephrine while waiting for antihistamines or other medications—this is associated with fatal outcomes 1, 2
• Do not use subcutaneous epinephrine or inject in the arm—IM thigh injection is superior 1, 2
• Do not assume the reaction is over after initial improvement—biphasic reactions can occur hours later and require 4-6 hours of observation 1, 2
• Avoid raising the patient to upright position during cardiovascular symptoms 2

Special Considerations

High-Risk Factors for Severe Reactions

• Coexisting asthma (especially poorly controlled) 1
• Adolescents and young adults 1
• History of previous severe anaphylaxis 1
• Delayed epinephrine administration 1, 2

Patients on β-Blockers

• Still give epinephrine—there are no contraindications in life-threatening anaphylaxis 1, 2
• May require higher doses or alternative vasopressors like glucagon 2

Multiple Stings

• Greater than 100 simultaneous stings can cause toxic reactions from massive envenomation that mimic anaphylaxis 1, 2

Post-Emergency Management

Before Discharge

• Prescribe epinephrine autoinjector (2 doses) and demonstrate proper use 1, 2
• Provide written anaphylaxis emergency action plan 1
• Refer to allergist-immunologist for venom-specific IgE testing and consideration of venom immunotherapy, which dramatically reduces future reaction risk 1, 2

Education on Avoidance

• Have nests removed by trained professionals 1, 2
• Avoid brightly colored clothing, flowery prints, and scented products 1, 2
• Wear long pants, long sleeves, closed shoes when outdoors 1, 2
• Be cautious near garbage containers and picnic areas 1, 2