What medication is used to treat a spider bite?

Medication Treatment for Spider Bites

For most spider bites, first-line treatment includes over-the-counter acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs) for pain management, with specific antivenom indicated for severe black widow spider envenomation. 1

Initial Assessment and Treatment Approach

• Most spider bites in North America cause only local symptoms and can be managed with supportive care 1
• Seek immediate medical attention if systemic symptoms develop, such as difficulty breathing, muscle rigidity, dizziness, or confusion 1
• First aid includes wound care, pain management, and ice application to the bite site 1

Treatment by Spider Type

Black Widow Spider Bites

• Black widow bites cause severe crampy pain, muscle rigidity, diaphoresis, and hypertension with minimal local tissue injury 1
• Treatment options include:
  • First-line: Over-the-counter analgesics (acetaminophen, NSAIDs) for mild pain 1
  • For moderate to severe pain: IV opioids and benzodiazepines have shown 55-70% effectiveness for symptomatic relief 2
  • Calcium gluconate, though traditionally used, has been found ineffective in providing pain relief in 96% of moderate to severe cases 2
  • Black widow spider-specific antivenom is highly effective for severe cases, resolving symptoms in approximately 31 minutes 2
  • Antivenom significantly reduces symptom duration (9 hours vs 22 hours) and hospitalization rates (12% vs 52%) compared to other treatments 2

Brown Recluse Spider Bites

• Treatment focuses on managing dermonecrosis that develops within 72-96 hours 3
• Management includes:
  • Rest and ice compresses 3
  • Antibiotics to prevent secondary infection 3
  • Dapsone may be beneficial 3
  • Surgical intervention should be delayed for several weeks 3
  • Systemic corticosteroids may help in rare cases of systemic loxoscelism with hemolysis 3

Local Wound Care

• Topical lidocaine (5%) can be applied if the skin is intact for pain relief 1
• Ice application helps reduce local pain and swelling 1
• Monitor for signs of secondary infection requiring antibiotics, including progressive erythema, purulent discharge, or systemic signs of infection 4

Special Considerations

• Epinephrine is the drug of choice for anaphylactic reactions to spider bites, administered at 0.01 mg/kg (up to 0.3 mg in children and 0.3-0.5 mg in adults) 5
• Very young, elderly, and those with underlying health conditions are at higher risk for severe reactions and may require more aggressive treatment 1
• Antihistamines and corticosteroids should not be considered substitutes for epinephrine in anaphylactic reactions 5

Common Pitfalls to Avoid

• Delaying epinephrine administration in anaphylactic reactions, which is associated with fatal outcomes 5
• Underestimating severity based solely on local findings at the bite site 1
• Using calcium gluconate as first-line treatment for black widow spider bites, which has been shown to be ineffective compared to other options 2
• Assuming antibiotics are needed for swelling around bite sites, as swelling is typically caused by mediator release, not infection 4