Brown Recluse Spider Bite: Symptoms, Treatment, and When to Seek Emergency Care

Identifying a Brown Recluse Bite

The brown recluse (Loxosceles reclusa) is a venomous spider found primarily in the central and southern United States. Bites are often initially painless but can progress to significant tissue damage.

Clinical Progression

Stage	Timeline	Features
Initial	0–2 hours	Mild stinging, erythema, small vesicle
Early	2–8 hours	Expanding erythema, central pallor/blanching, "target" lesion
Necrotic	24–72 hours	Central blister → necrosis → eschar formation, possible ulceration
Systemic (rare)	24–72 hours	Fever, chills, nausea, hemolysis, DIC, renal failure (loxoscelism)

Immediate First Aid

1. Cleanse: Wash with mild soap and water.
2. Cold compress: Ice pack wrapped in cloth, 15 min on/off for pain/swelling.
3. Elevate: Affected limb above heart level.
4. Immobilize: Limit movement of the area.
5. Do NOT: Apply heat, cut/suction the wound, use tourniquets, or apply topical antibiotics/steroids initially.

Medical Management

• Observation: Most bites are self-limiting; monitor for progression.
• Wound care: Daily cleaning, non-adherent dressings, debridement if necrotic.
• Pain control: NSAIDs, acetaminophen; opioids rarely needed.
• Antibiotics: Only if secondary infection develops (cellulitis, abscess).
• Tetanus prophylaxis: Update if >10 years since last booster.
• Dapsone: Controversial; sometimes used for impending necrosis but lacks strong evidence and carries hemolysis risk (especially in G6PD deficiency).
• Antivenom: Not commercially available in the US; investigational only.
• Surgical referral: For large necrotic ulcers, delayed healing, or reconstruction.

When to Seek Emergency Care

• Signs of systemic loxoscelism (fever, dark urine, jaundice, altered mental status)
• Rapidly expanding necrosis or erythema >10 cm
• Signs of secondary infection (purulence, streaking, lymphangitis)
• Bite on face, neck, hands, or genitals
• Immunocompromised patient or child

Prevention

• Shake out clothing/shoes stored in closets, attics, basements
• Use sticky traps, reduce clutter, seal cracks
• Wear gloves when handling firewood, boxes, stored items

Note: Many suspected "spider bites" are actually MRSA abscesses, other insect bites, or dermatological conditions. Confirmation requires spider identification.