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Management of Scorpion Sting (Envenomation)

1. Overview

• Harrison's Principles of Internal Medicine 22E (2025), p. 3778

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2. Pathophysiology

• Neurotoxins - keep neuronal sodium channels open causing prolonged/excessive depolarization; affect somatic and autonomic (sympathetic + parasympathetic) systems
• Hemolysins, agglutinins, hemorrhagins, proteinases, phospholipase A, coagulins

• P.C. Dikshit Textbook of Forensic Medicine and Toxicology, p. 501

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3. Clinical Features

Local (most stings)

• Immediate sharp, burning pain at sting site
• Edema, erythema, a central punctum ("red wheal with hole")
• Paresthesia and hyperesthesia, accentuated by tapping (the "tap test")
• Typically resolves within a few hours

Systemic - Graded Severity

• Restlessness, agitation, uncontrolled jerking (may mimic seizure)
• Profuse salivation, lacrimation, rhinorrhea
• Difficulty handling secretions - airway threat
• Tachycardia, arrhythmias, hypertension, hyperthermia
• Rhabdomyolysis, acidosis
• Fatal respiratory arrest most common in young children and elderly

• Hypertensive crisis, arrhythmias, pulmonary edema, myocardial damage

• Initially mild, then pain, hemolysis, tissue necrosis after day 1
• Hemoglobinuria → acute kidney injury
• Tintinalli's Emergency Medicine, p. 1397; Harrison's 22E, p. 3778-3779

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4. Management

A. Initial Assessment and First Aid

1. Identify the scorpion species if possible - guides treatment intensity
2. Keep the patient calm and still
3. Apply pressure dressings and cold packs (NOT hot packs - vasodilation accelerates venom spread and is contraindicated)
4. Elevate the affected limb
5. Tetanus prophylaxis if not current

B. Grade 1 & 2 (Local/Mild)

• Can often be managed at home with instructions to return if systemic signs develop
• Analgesia: acetaminophen, NSAIDs, or local lidocaine (without epinephrine) injection at sting site
• Antihistamines for allergic features
• Ice packs (cryotherapy) - reduce swelling and retard systemic absorption
• Avoid opiates - they appear to increase toxicity (increase systemic effects)

C. Grade 3 & 4 (Severe/Systemic) - Emergency Management

Airway & Monitoring

• IV access, continuous monitoring
• Airway management is priority - hypersalivation + cranial nerve dysfunction threatens airway integrity
• Watch for respiratory compromise, especially with sedatives

Sedation / Neuromuscular Agitation

• Midazolam (continuous IV infusion) - reduces agitation and involuntary movements
• Benzodiazepines generally preferred for neuromuscular agitation
• Caution: sedatives and opiates require close monitoring due to risk of respiratory compromise

Cardiovascular Complications

• Rosen's Emergency Medicine, p. 822; Harrison's 22E, p. 3779

Antivenom

• Indicated for Grade 3 and 4 envenomations
• Species-specific; administer presumptively based on most common local species if identity uncertain
• FDA-approved: Equine-derived C. sculpturatus IgG F(ab')2 - Anascorp (Centruroides immune F[ab]2)
  • Dose: 3 vials IV as soon as possible; additional 1 vial every 30-60 min as needed
  • Reverses cranial-nerve dysfunction and muscular symptoms rapidly
  • Effective and safe in clinical trials; most evidence is in children/young adults
• In adults, supportive care is often sufficient; antivenom is generally not considered essential in adults with moderate symptoms
• Risk of immediate allergic reaction and serum sickness (delayed) - monitor post-administration
• Antivenins available in several countries for the most dangerous local species

Note: Antivenom is most effective when given early after the sting

• Rosen's Emergency Medicine, p. 821-822; Tintinalli's EM, p. 1397; Harrison's 22E, p. 3779

Specific Treatments (India context - Mesobuthus tamulus)

• Prazosin (alpha-1 blocker) is especially effective for catecholamine excess and cardiovascular compromise
• Combine with antivenom for best results in cardiovascular presentations

Additional Supportive Measures

• Calcium gluconate 10 mL of 10% IV - for severe muscular cramps
• Glucocorticoids IM + IV dextrose-saline - for shock
• Atropine sulphate - to prevent/treat pulmonary edema (secretion control)
• IV fluids and close monitoring for renal function (Hemiscorpius stings)
• P.C. Dikshit Forensic Medicine and Toxicology, p. 501

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5. Summary Treatment Table (Tintinalli's)

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6. Disposition

• Grade 1-2: Home with return precautions
• Grade 3-4: Admit for monitoring, antivenom, and supportive care
• Symptoms peak at ~5 hours, subside within 1-2 days; pain/paresthesia may persist weeks

7. Prevention

• Wear shoes and shake out clothing/shoes before wearing
• Remove debris, wood, and rocks around dwellings
• Chemical pesticides to reduce scorpion populations
• Inspect bedding, especially in endemic areas

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1. Most stings are local only and need only analgesia + ice; avoid hot packs and opiates
2. Species identification guides treatment intensity
3. Midazolam IV for neuromuscular agitation; prazosin for cardiovascular catecholamine effects
4. Antivenom (Anascorp) for Grade 3-4 - give early IV, 3 vials initially
5. Airway management is the top priority in severe systemic envenomation
6. Young children are at greatest risk for fatal respiratory arrest