From the Guidelines
Spider bites can present with various cutaneous signs, and treatment should prioritize symptom management and prevention of complications, with immediate medical attention sought for severe bites or systemic symptoms, as recommended by the 2024 American Heart Association and American Red Cross guidelines for first aid 1. The cutaneous signs of spider bites can vary depending on the species involved, with common signs including localized pain, redness, swelling, and itching at the bite site. More serious bites, particularly from black widows or brown recluse spiders, may develop a characteristic bull's-eye pattern with a pale center surrounded by redness, or a necrotic ulcer with a blue-purple discoloration. Some key considerations for treatment include:
- Washing the area with soap and water to prevent infection
- Applying cold compresses to reduce swelling
- Taking over-the-counter pain relievers like acetaminophen or ibuprofen (400-600mg every 6 hours as needed) for pain management, as suggested by the guidelines 1
- Using antihistamines such as diphenhydramine (25-50mg every 6 hours) for itching
- Elevating the affected limb to reduce swelling For severe bites or systemic symptoms, immediate medical attention is necessary, with treatment potentially including prescription antibiotics, tetanus prophylaxis, or antivenom, as outlined in the guidelines 1. It is essential to note that the effects of spider and scorpion envenomation can vary widely, and these guidelines are relevant to spider bites and scorpion stings occurring in the United States and Canada 1.
From the Research
Cutaneous Signs of Spider Bite
- Most spider bites cause minimal or no effects, with local irritation being the most common symptom 2
- Some spiders, such as the brown recluse and Hobo spider, can cause severe cutaneous and systemic reactions, including dermonecrosis and necrotic arachnidism 3
- Latrodectism, caused by the red back spider, is characterized by pain, including local, radiating, and regional pain, with systemic symptoms occurring less commonly 2
Treatment of Spider Bites
- Most spider bites require little treatment, with basic wound care, including cleansing and irrigation, being sufficient 3, 4
- In some cases, such as bites from the brown recluse or Hobo spider, intensive medical management may be required, including the use of antibiotics to prevent secondary infection 3, 4
- Antivenin may be necessary for bites from certain spiders, such as the black widow, which can cause severe neurologic problems 3
- A pressure immobilisation bandage should be applied and the patient transferred to a hospital with available antivenom and resuscitation facilities in the case of a funnel web spider bite 2